2.1. Dworkin’s Interpretive Thesis^{Footnote 18}

The Interpretive Thesis offers an account of interpretive—or political—concepts and how propositions about these concepts can be true or false.^{Footnote 19} According to Dworkin, “we share an interpretive concept when our collective behavior in using that concept is best explained by taking its correct use to depend on the best justification of the role it plays for us.”^{Footnote 20} We need interpretive concepts to describe values such as liberty, equality, justice, democracy, and so on, or interpretive practices such as law, morality, or courtesy. In these realms, we lack a factual agreement about the content of the concepts we use, and the meaning of these concepts is functionally related to the purpose of the practices we purport to explain.

On Dworkin’s view, interpretation is not merely a process to determine the meaning of words or authoritative pronouncements. It is, instead, a justificatory reasoning we must adopt when we argue that certain propositions—interpretive propositions—are true or false. To establish the truth of an interpretive proposition one requires an attitude that takes into account not only the linguistic content of a given sentence, but also the point of the practice in which such proposition is sustained.^{Footnote 21}

According to Dworkin, depending on the practice we engage we must use different types of concepts: “we must accept what Wittgenstein pointed out: that concepts are tools and that we have different kinds of tools in our conceptual toolbox.”^{Footnote 22} Archimedean theories—which claim to be “second-order philosophical theories” that are “neutral, philosophical and uncommitted”—might be appropriate for some of these practices.^{Footnote 23} But it is a mistake, Dworkin argues, to think that all practices and all concepts can be explained with an Archimedean theory. Once we argue about interpretive practices we must use interpretive concepts. When using criterial concepts, one can expect a settled list of features for instantiation of shared criteria, and when using natural kind concepts, one can expect an experiment or verification process to identify a natural fact. But with interpretive concepts none of this will do. When we try to deploy criterial or natural kind concepts to explain an interpretive practice such as “law”, we commit a mistake called the “semantic sting.” The semantic sting, according to Dworkin, “lies in the assumption that all concepts depend on a convergent linguistic practice … that marks out the concept’s extension either through shared criteria of application or attaching the concept to a distinct natural kind.”^{Footnote 24}

To understand the force of Dworkin’s approach to interpretation we must leave Archimedeanism behind and acknowledge that it is incapable of explaining interpretive practices. In interpretive practices, language users lack a decisive test to establish the truth or falsehood of the claims that they make or contest. It is wrong to assume—as Archimedean philosophers do—that the substantive value judgments of ordinary people and the philosophical analysis of such judgments are at different levels of discourse.^{Footnote 25} When we argue about morality, for instance, there is no distinction between questions of morality and questions about morality, since both of these questions are situated on the same level.^{Footnote 26}

Interpretation is a distinct intellectual process that entails, for interpreters, a special type of responsibility to the practice in which they participate.^{Footnote 27} In short, as Dworkin expressed in one of his most famous contentions, an interpretation of a social practice “must both fit that practice and show its point or value.”^{Footnote 28} The truth of an interpretive proposition depends not only on the application of some linguistic criteria or scientific test, but rather, at least in an important part, on a normative judgment of the interpreter. One cannot interpret a concept correctly without assuming the political and moral responsibilities involved in that judgment. It is this normative position about the interaction between interpretation and purpose that constitutes the core of the Interpretive Thesis. The point of Dworkin’s famous analogy between law and courtesy, which appeared at the core of Law’s Empire, is to make clear that one cannot understand interpretive practices without “an attitude that has two components:” first, “the assumption that the practice of courtesy [or law] does not simply exist but has value”, and second, “the further assumption that the requirements of courtesy [or law]—the behavior it calls for or judgments it warrants—are not necessarily or exclusively what they have always been taken to be but are instead sensitive to its point, so that the strict rules must be understood or applied or extended or modified or qualified or limited by that point.”^{Footnote 29}

When Dworkin refers to interpretive concepts, such as “law” and “morality”, he is considering argumentative practices in which purpose is especially important for truth. Interpretation differs from science, for instance, “because interpretation is purposive, not just in vocabulary but in the standards of its success.”^{Footnote 30} It is “part of the organizing structure” of science that “justifying goals have nothing to do with truth.”^{Footnote 31} You can make a plausible scientific theory about the movement of planets no matter what the justifying purpose of your enquire is. You do not need to make any moral or political judgment to understand the laws of physics that determine the movement of these planets, and your inquiry is completely independent of the purpose of these laws, if there is such a purpose. Interpretation, in turn, is an entirely different matter. In the realm of interpretation “justifying purpose is at the heart of success.”^{Footnote 32} When we interpret, “our standards for success in an interpretive genre” depend “on what we take to be the best understanding of the point of interpreting that genre.”^{Footnote 33} We give a right answer to a question whether an interpretive proposition is true only if we grasp the point of the interpretive genre to which it belongs and we construct the object of our interpretation in the best possible way.

After discussing Dworkin’s general theory of interpretation, it should be clear how interpretive concepts differ from “criterial” and “natural-kind” concepts: the use of any of such concepts depends on the context of different social practices. In all these concepts there is room for disagreement, so what matters is how these disagreements are resolved. If you and I disagree whether someone is a “bachelor”, we can understand “bachelor” as a criterial concept and appeal to a social agreement to figure out how our disagreement is best resolved. If we disagree whether some feline is a cheetah or a leopard, we are probably talking about a natural kind concept and we can make some DNA test to determine the species of that big cat. But when we use interpretive concepts and disagree about these concepts our disagreements are “value disagreements rather than disagreements of fact or disagreements about dictionary or standard meanings.”^{Footnote 34} When, for instance, liberals and conservatives debate whether progressive taxation is just or unjust, they cannot be adopting a criterial concept of justice, since they lack common criteria to determine what justice is. They disagree about the concept of justice, but they can still be said to share the concept of justice “because they participate in a social practice of judging acts and institutions just and unjust and because each has opinions, articulate or inarticulate, about what the most basic assumptions of that practice, its point or purpose, should be taken to be.”^{Footnote 35}

Dworkin’s Interpretive Thesis, therefore, is a theory about how interpretive propositions—which include propositions about values and social practices—can be legitimately recognized as true or false. The need for an interpretive concept of law arises when we use the concept of law in the doctrinal context in which we purport to justify our propositions about the rights and duties that we have in the political community. Dworkin’s jurisprudence, in fact, is concerned only with the doctrinal concept of law. In Law’s Empire, Dworkin stresses for several pages that his conception of interpretation is constructive, and that it is “essentially concerned with purpose and not cause.”^{Footnote 36} It is “a matter of imposing purpose on an object or practice in order to make it the best possible example of the form or genre to which it is taken to belong.”^{Footnote 37} But how does someone impose a purpose on an object or a practice? Dworkin answers that one of the key features of law is that it is an argumentative social practice. Hence, “every actor in the practice understands that what it permits or requires depends on the truth of certain propositions that are given sense only by and within the practice: the practice consists in large part in deploying and arguing about these propositions.”^{Footnote 38}

When we deploy our arguments in an interpretive practice, we need not to appeal to basic or ultimate moral facts. According to Dworkin, our statements about morality are “statements within rather than about the enterprise of morality.”^{Footnote 39} When I deploy an argument for the moral proposition that “slavery is objectively wrong”, I need not to show that some “atmospheric moral quaverings confirm my opinion, for example, or that it matches a noumenal metaphysical fact.”^{Footnote 40} Rather, “the practices of interpretation and morality give these claims all the meaning they need or could have.”^{Footnote 41}

Given the One-System Thesis, these conclusions are equally applicable to the practice of law. The internal aspect of the practice of law has important consequences for Dworkin’s jurisprudence. Philosophical theories of law must be abstract because they “aim to interpret the main point and structure of legal practice.”^{Footnote 42} But since this practice is argumentative and sensitive to the arguments about the grounds of the practice itself, legal philosophers cannot step out of this practice. The arguments they make are also part of this practice, no matter how abstract they are. This is the core of Dworkin’s famous assertions that “no firm line divides jurisprudence from adjudication or any other aspect of legal practice” and that jurisprudence is a “silent prologue to any decision at law.”^{Footnote 43} Interpretation, for Dworkin, is a way to make sense of a social practice from within that same practice, and not from an external point of view. “The only argument that can provide a reason for endorsing or abandoning or qualifying a legal judgment is a legal argument, and that holds for morality and art and science as well.”^{Footnote 44} Dworkin’s jurisprudence, like his moral philosophy, is radically Anti-Archimedean, as Ripstein explains in the following text:

2.2. Greenberg on the Rational Determination of Law

Greenberg’s explanation of how morality contributes to the content of the law is very different, given that he has a different approach to morality and interpretation. The first step to understand Greenberg’s departure from Dworkin’s position about the character of legal concepts is to consider his way of framing the controversy between positivist and non-positivist conceptions about the nature of law. In a sophisticated paper about the metaphysical foundations of law, which predates his more recent writings on the Moral Impact Theory, Greenberg claimed that the content of the law depends “not just on descriptive facts but on value [or moral] facts as well.”^{Footnote 46} Once this argument is specified, we need a richer philosophical vocabulary to understand his point.

According to Greenberg, “nearly all philosophers of law agree that non-normative, non-evaluative, contingent facts—descriptive facts, for short—are among the determinants of the content of the law.”^{Footnote 47} The controversial issue is only whether these descriptive social facts are the exclusive determinants of legal content, or whether moral facts (or, more broadly, evaluative facts) are also necessary to determine the content of the law. According to Greenberg, this debate is metaphysical or constitutive, and “only secondarily epistemic”,^{Footnote 48} for the central question in this discussion is what makes the content of the law what it is, and not how we get to know about this content.

According to Greenberg, we need a metaphysical theory to explain the making of the law because the “legal-content facts”, i.e., the social facts that constitutively determine the law, are not “metaphysically basic or ultimate facts about the universe.”^{Footnote 49} A complete metaphysical explanation of the foundations of law must, therefore, explain not only the descriptive facts that constitutively determine the content of the law, but also the more fundamental facts that make these descriptive facts rationally intelligible. To clarify this point, Greenberg proposes to distinguish the notions of metaphysical or constitutive determination^{Footnote 50} from that of rational determination, although both appear as metaphysical concepts.^{Footnote 51}

When it comes to the constitutive or metaphysical determination of law, Greenberg thinks that both sides of the positivist versus non-positivist debate can agree that “descriptive facts alone metaphysically determine the content of the law”, since both accept that “even if value facts are relevant to the content of the law, it is still true that the content of the law could not be different from what it is without the descriptive facts being different.”^{Footnote 52} Nonetheless, constitutive determination is not sufficient to tell us what the content of the law is. There must be something that makes such descriptive facts intelligible, which cannot be confused with the descriptive facts themselves. It is here, for Greenberg, that the idea of rational determination comes into play.

Suppose we agree that the law-determining practices such as legislation, precedent and other acts of legal institutions constitutively determine the content of the law. For Greenberg, this constitutive determination is not sufficient to fix the content of the law because constitutive determination can be brute. According to Greenberg,

This is, briefly stated, Greenberg’s rational determination doctrine . If this doctrine is accepted, the social facts in virtue of which the law has the content it has “cannot determine their own significance”, and moral facts are “needed to make it intelligible that law practices support certain legal propositions over others.”^{Footnote 54} It follows from the rational determination doctrine that there must be “systematic” and “intelligible” connections between “practices and the content of law.” There must be “rules that, given any pattern of law practices, yield a total set of propositions.”^{Footnote 55} A “model of the role of law-determining practices in contributing to the content of law”, or simply a “model”, for short, is such a “rule or set of rules.”^{Footnote 56} Given that we need a model to determine the significance of legal practices, Greenberg rejects the idea that legal practices themselves can provide a model or even adjudicate between alternative models that we offer to explain them. Legal practices cannot determine which model is correct even if the content of the law includes “rules for the bearing of law practices on the content of law”, and the reason is simple: the content of the law itself “depends on which model is correct.”^{Footnote 57}

Greenberg’s rational intelligibility doctrine, summarized in the previous paragraph, provides the basis of a stronger philosophical claim, which holds that value facts, or moral facts, are the best candidates to determine the relevance of law practices. Value facts, for Greenberg, “include facts about the relevance of descriptive facts” and, “at least in the case of the all-things-considered truth about relevant values”, their relevance is “intelligible without further reasons.”^{Footnote 58} They are the best candidates to meet the rational-relation requirement and function as the reasons that determine the contribution of legal practices for the content of the law.^{Footnote 59} The crucial step in Greenberg’s reasoning, as Barbara Levenbook explains, is the contention that the rational intelligibility requirement is an appeal to an “external validation of a theory’s reasonableness.”^{Footnote 60} According to Greenberg, proponents of the positivist social fact thesis fail to explain the content of the law because they only have resources to offer an internal validation for their own tenets to determine the content of the law.^{Footnote 61}

It is interesting to observe that Greenberg’s argument, if sound, would be a problem not only for Hart and the supporters of the social fact thesis, but also for Dworkin. Greenberg is postulating a rational intelligibility requirement that steps outside of the practice of legal argumentation. The value facts to which he appeals are external from legal practice and do not depend on interpretation. Greenberg’s requirement is a second-order theory of intelligibility, which can be true only if Dworkin’s contention that legal philosophers use propositions about the grounds of law that “are given sense only by and within the practice” is false. For Dworkin, “answers to large questions about moral truth and knowledge” must be sought within morality, not outside it.^{Footnote 62} By the same token, granted the One-System Picture, questions about legal truth and the grounds of law are also internal questions of the practice of law. This point provides, I submit, the key to distinguish between Greenberg and Dworkin in their conceptions of law.

When Greenberg advocates that one needs moral facts to make the social determinants of law rationally intelligible, he must appeal to moral facts that are practice-independent in the sense that they precede the social practice of law and are probably not dependent on the attitude and the arguments of the practice’s participants. Greenberg’s ultimate moral facts, which are postulated to satisfy the rational intelligibility requirement, approach the practice of law from a second-order point of view. They stand at a different level, and so does the legal theorist who tries to understand them.

If, along with Greenberg, we describe the inquiry over the determinants of the content of the law as a metaphysical explanation of how legal facts obtain, then Dworkin’s assertion that legal theory rests on ordinary moral and ethical judgments can no longer be upheld. As Dworkin explains in response to Hart, his methodological point against conceptual theories of legal positivism concerns the “connection between theory and practice”, for he believes that “it follows from the interpretive character of law that jurisprudence must be interpretive too.”^{Footnote 63} On Dworkin’s view, any legal theory must be interpretive because there is no second-order and non-evaluative theory that can provide an adequate understanding of an interpretive concept. The idea that we need an interpretive theory to explain an interpretive practice is central to Dworkin. As indicated by Stephen Guest, “it follows from the fact that moral concepts are interpretive that they can’t be analyzed neutrally. Engaging in what the best sense is of a particular moral concept rules out a non-committed, detached and neutral account.”^{Footnote 64}

If Dworkin is right about the nature of legal argument, there is no external standpoint to which one can resort in order to apply a second-order test to determine the status of a legal fact. Unlike the Moral Impact Theory, Dworkin’s Law as Integrity does not assume the existence of practice-independent moral facts. As Dennis Patterson explains, Dworkin’s view in Law’s Empire is that “the meaning of ‘justice’ is not fixed by identifying a normative core but by appeal to the participant’s own sense of the point or purpose of the institution in question.”^{Footnote 65} For Dworkin, “a useful analysis of an interpretive concept—beyond the bare statement that it is interpretive and a very general account of the practices in which it figures—cannot be neutral. It must join issue in the controversies it hopes to illuminate.”^{Footnote 66}

Greenberg’s theory, in turn, conveys a different intellectual attitude. Greenberg’s explanation of how facts make law is, on Dworkinian terminology, an Archimedean theory of law that purports to be conceptual and descriptive. Like the conceptual methodology adopted by most forms of legal positivism, Greenberg’s Moral Impact Theory seems to figure amongst the Archimedean theories that “claim not themselves to be normative theories”, in the sense that they “claim rather to be philosophical or conceptual theories that are only descriptive of the social practice and neutral among the controversies that make up that practice.”^{Footnote 67} He postulates, to satisfy the rational intelligibility requirement that he upholds, the existence of moral facts whose content is not determined by interpretation. Greenberg is not an interpretivist, since his theory must assume, by implication, the existence of ultimate moral facts. He calls these ultimate moral facts fundamental value facts and assumes as uncontroversial that “the fundamental value facts are metaphysically necessary.”^{Footnote 68}

Since Greenberg believes we do not need constructive interpretation to determine the fundamental value facts, he argues that “working out the content of law is not a genuinely hermeneutic enterprise”, and involves instead a “straightforward moral reasoning about the moral consequences of various facts and circumstances.”^{Footnote 69} I think this is the most important difference between Greenberg and Dworkin. Given that both authors believe we must resort to moral considerations to determine the content of the law, the central difference between the two positions concerns how we should establish the truth of a moral proposition. While Greenberg assumes that there must be some basic or underived moral facts (the fundamental moral facts), which make legal-content facts rationally intelligible at the ultimate level, Dworkin thinks that moral propositions are true only to the extent that they are redeemed by a sound interpretation.^{Footnote 70} Dworkin’s interpretive theory of law is not and should not be transformed into a metaphysical theory of law.^{Footnote 71}

3.1. Greenberg’s Statement of the Difference between his Theory and Dworkin’s Interpretivism

Even though Dworkin lacks a metaphysical theory of law, Greenberg appears to overlook this when he tries to distinguish the Moral Impact Theory from Dworkin’s theory of law. He makes a set of critical claims against Dworkin, which purport to show that his account is a better version of the One-System Thesis. Given what Greenberg says while comparing his own theory with Dworkinian interpretivism, I believe he envisages three differences that make his theory superior to Dworkin’s Law as Integrity (1. Dworkin’s Judicial Enforceability Thesis; 2. Dworkin’s resort to idealized principles; and 3. The possibility of conflicts between legal and moral obligations in Dworkin’s theory of law). Nevertheless, I believe these differences come down to different aspects of the same issue, which is the possibility of a metaphysical theory of law. I argue in this section that Greenberg’s criticisms against Dworkin are unsound. His objections to Law as Integrity are inaccurate because they implicitly assume Dworkin is also proposing a metaphysical theory about the determinants of the law. Greenberg misses, therefore, the really important difference between his theory and Dworkin. It is this fourth difference that provides the key to dissolve Greenberg’s arguments against Dworkin, as I try to show in the next paragraphs.

Judicial Enforceability. First, Greenberg argues that under Dworkin legal rights are a class of political rights which are “enforceable upon demand”, whereas on the Moral Impact Theory institutional enforceability is not a necessary feature of law.^{Footnote 72} Given Dworkin’s view that law is a department of morality, the specific feature to distinguish a legal right from a general political right would be the judicial enforceability of the former.

Greenberg’s target is the claim that Dworkin raises in the final chapter of Justice for Hedgehogs, where legal rights are defined as “those that people are entitled to enforce on-demand, without further legislative intervention, in adjudicative institutions that direct the executive power of Sheriff or police.”^{Footnote 73} He believes Dworkin gives only an “extremely weak” argument for this position. Briefly stated, Dworkin’s argument is that we cannot accept law and morality as separate systems of norms because “any attempt to answer the question of whether the content of the law depends on the content of morality must be viciously circular.”^{Footnote 74} When we ask whether legal positivism or interpretivism is more accurate, Dworkin assumes that if law and morality were different systems we would be stuck with two mutually exclusive alternatives: either law or morality would have to specify the relation between these separate domains, and both alternatives are question-begging.^{Footnote 75}

To respond to this argument, Greenberg maintains that Dworkin is wrong to formulate the question in this way because the separability between law and morality is not an internal affair of either law or morality, but rather a “metaphysical question about the relation between the two domains.”^{Footnote 76} When Dworkin suggests treating law and morality as part of a single system of values, Greenberg thinks he “blatantly begs the question against his positivist opponents”,^{Footnote 77} who provide, according to Greenberg, a metaphysical argument for the autonomy of law. Nonetheless, I think that Greenberg is the one who begs an important question in this criticism, for he does not even begin to assess the “most radical view”—and perhaps also the most important point—that Dworkin defends in Justice for Hedgehogs, which is the thesis of the “metaphysical independence of value.”^{Footnote 78} On this view, whether any moral assertion is true “is a matter of moral judgment and argument.”^{Footnote 79} If there is a way to show that moral judgments are true, it must be by offering a further moral argument belonging to the same level of discourse:

The whole point of the argument in Justice for Hedgehogs, as Guest explains, is to “demolish the idea of second-order theorizing about morality”, such that an account of morality must be based “entirely on evaluative judgments.”^{Footnote 81} There can be “no arguments for the objectivity of moral judgments except moral arguments, no arguments for the objectivity of interpretive judgments except interpretive judgments, and so forth.”^{Footnote 82} It is only because of this thesis that Dworkin is skeptical about meta-ethics and ends up advocating that we should not seek for answers about what makes a “moral fact” or a “legal fact” in abstract metaphysical theories.

In order to provide a solid criticism against Dworkin’s thesis of the unity of law and morality—which stems from the more abstract thesis of the unity of value—Greenberg should tell us why Dworkin’s argument against the possibility of non-moral metaphysical claims about morality or law is false.^{Footnote 83} Although Greenberg recognizes that if this thesis were true “it would indeed be hard to see how one could answer the question of the relation between law and morality”, he merely says that the thesis is “confused” and begs the question of whether it is correct.^{Footnote 84}

Furthermore, I suspect that Greenberg fails to understand the actual importance of the Enforceability Thesis in Dworkin’s theory of law. Under Dworkin, the point of a conception of law is not to provide an Archimedean description of the practice of law. It is to show the practice of law in its best light, i.e., to “deploy some argument why the law on that conception provides an adequate justification for coercion.”^{Footnote 85} Legal theory is regarded as part of a political theory of legitimacy. Thus, the main question is neither who enforces the law nor whether there are specific laws that can be valid even though they cannot be judicially enforced. Rather, the gist of Dworkin’s argument is that law must be construed as legitimate or justified. Institutional enforceability matters because Dworkin is considering a doctrinal concept of law, which is a concept we employ when it matters what rights and duties we have in our political community, in the sense that some practical consequence follows from the truth of the legal propositions we hold. As Dworkin states in the initial pages of Justice in Robes, his jurisprudence is mainly concerned with the doctrinal sense of the concept of law. When we argue about law in that way,

When Dworkin considers the doctrinal concept of law, he wants to know what our rights are and what correlative obligations can be legitimately enforced. As Stephen Perry puts it, Dworkin’s legal theory is linked with his theory of political obligation: the latter “does not treat the question whether there is ever a general obligation to obey the law as independent from the philosophical problem about the nature of law.”^{Footnote 87} Dworkin says that legal rights are enforceable, normally by judicial institutions, because he wants to distinguish these rights from the general category of “political” rights.^{Footnote 88} Dworkin’s enforceability argument can be read, therefore, in the sense suggested by Jeremy Waldron when he claims enforceability is one of the central features we should expect to find in a fruitful account of Natural Law. Natural Law, for Waldron, must be enforceable not in the sense that there is a coercive apparatus for its application, but in the sense of “being appropriate, or at least not inappropriate, to uphold a given norm with force.”^{Footnote 89}

Even Greenberg might be happy with this version of the enforceability argument. The “Judicial Enforcement Theory”—the name Greenberg assigns to Dworkin’s view about the enforceability of rights—can be compatible with “a variant of the Moral Impact Theory”^{Footnote 90} if it is revised in one of the following two ways: first, if we abandon the assumption that legal obligations are ones that people are always “entitled to enforce on-demand”, and argue that “courts have a pro tanto obligation to enforce them”, in the sense that “it is permissible for courts to enforce or that courts are entitled to enforce;”^{Footnote 91} second, if we “broaden the focus from adjudicative institutions to legal institutions generally”, allowing for the existence of legal rights that are enforceable by other institutions.^{Footnote 92} As we can see, neither Dworkin’s fundamental argument about the nature of morality and law, nor Dworkin’s One-System Thesis would be substantially affected if we followed Greenberg’s two suggestions. Dworkin’s theory survives unharmed.

Dworkin is probably right to think that we ordinarily use the concept of law in the doctrinal sense, and that in this context our arguments about the content of the law are put forward in order to know what rights can be duly enforced. We might think of different ways to use the concept of law, for instance, if we want a sociological concept to describe the notion of legal system accepted in a particular community. But even if we can imagine one particular type of use of the concept of law in which some part of “the law” is not enforceable by judges or other legal institutions, we need not think Dworkin’s theory of law will suffer from severe damage, since his worry is not about necessary properties of law, but only about building a conception of law that is consistent with how the law works in our political debates. To restate the point: Dworkin’s is a theory of legitimate law, not a metaphysical explanation of the ontology of law.

It is because of the need to provide an account of the legitimacy of law that Dworkin thinks jurisprudence must use an interpretive concept of law. Dworkin never argued against the logical or linguistic possibility of using criterial concepts to identify the law. He thinks it is possible to define the law, by stipulation, in such a way that “recognizes as ‘legal’ standards only those standards judges and lawyers cite that are in fact identified by some commonly-recognized test.”^{Footnote 93} Nonetheless, this picture is unsatisfactory because it fails to fit legal practice when the law is employed in the institutional context of courts and officials, who make a justificatory use of the concept of law in order to identify the “rights and duties that a government has a duty to recognize and enforce.”^{Footnote 94} If we employ the concept of law in order to determine what rights and duties we have and what measures can be legitimately enforced upon those of us that fail to comply with these duties, then we must use a doctrinal concept of law, which has always a justificatory function.

Principles and Legal Justification. Second, Greenberg maintains that under Dworkin the law should be found in idealized sources^{Footnote 95} or in principles “upstream” of legal practices, such that we should classify as legal the principles of political morality that justify ex ante the action of legal institutions.^{Footnote 96} Greenberg shares with Stavropoulos, therefore, the impression that Dworkin assumes that in the order of explanation, moral principles come before legal facts.^{Footnote 97}

Nonetheless, this description neglects the interpretive character of justification in Dworkin’s philosophy of law. When Greenberg claims that under Dworkin the law is what justifies ex ante the action of legal institutions, he seems to treat justification and interpretation as separate processes. He uses his own notion of justification, instead of Dworkin’s.^{Footnote 98} According to Greenberg, the relevant question for Dworkin is not what a statute says, let alone what moral duties we have in virtue of that statute. Rather, it is “what principles would have justified the enactment of the statute.”^{Footnote 99} Once we identify these principles, we have successfully established the content of the law. Nonetheless, this description is inaccurate if we fail to explain how Dworkin sees the relation between interpretation and justification. On Dworkin’s view, justification is an aspect of interpretation. We cannot say that a principle justifies something without adopting an interpretive attitude towards this principle, for the very existence of this principle is not a brute moral fact. To interpret morality is to produce a moral argument in support of a moral proposition that is supposed to integrate itself in the web of moral convictions that one accepts. You cannot step out of morality during this process because there is neither an agreed procedure for testing moral propositions nor a set of moral particles in nature that could make something a valid moral claim.^{Footnote 100} The truth of a moral claim must be established from within morality. Interpretation, for Dworkin, is not a process of discovery. Rather, it has a performative aspect: “interpretation is interpretive, just as morality is moral, all the way down.”^{Footnote 101} Interpretation provides the way to make a case for the truth of any given moral proposition, and involves a special discipline or responsibility to pursue moral truths by an integrative reasoning process: “the nerve of responsibility is integrity and the epistemology of a morally responsible person is interpretive.”^{Footnote 102}

The same can be said about law. This is important to understand the relation between fit and justification in Dworkin’s theory of law. The dimension of fit is added when we move from morality to law because the law has an institutional aspect that morality lacks. The historical political decisions of the community always matter in legal argument.^{Footnote 103} Because of the mutual dependence between fit and justification, which are regarded as two equally important aspects of legal integrity, legal justification is not free-standing; it is not independent from the practice of law.^{Footnote 104} The theories we employ to justify a legal proposition are embedded in legal practices.^{Footnote 105} If a moral argument does not fit the law practices it purports to justify, any justification based on this argument will be flawed. What makes the ideas of fit and justification mutually supportive in Dworkin’s account of law is the fact that both are required for the success of any legal interpretation. Interpretation, for Dworkin, is not external to the practice or the realm that constitutes its object. The content of principles does not precede interpretation. There is an important circularity in interpretation that Greenberg appears to miss because he sees justification as independent from that which it purports to justify. Interpretation for Greenberg has nothing to do with justification, whereas for Dworkin the opposite is true. As Gerald Postema explains, Dworkin’s view is that the content of legal practices is made by the arguments that are employed by the participants of these practices: “social practices are not only meaningful human activities, but they are meaningful to those who take part in them.”^{Footnote 106} The participants’ understanding of the social practice of law is in some way “constitutive of the practice”, whereas the observers’ understanding is “logically parasitic upon that of the (self-identified) participant.”^{Footnote 107} No observer can understand a social practice “until he has his own sense of what counts as a good or bad argument within the practice.”^{Footnote 108}

Tradeoffs between Law and Morality. The third difference that Greenberg sees between the Moral Impact Theory and Law as Integrity concerns the possibility of tradeoffs between legal and moral obligations. According to Greenberg, the Moral Impact Theory upholds that the law cannot diverge from what morality requires, whereas Dworkin’s Law as Integrity is constrained by the requirement of fit in such a way that the content of the law can be very different from our all-things-considered political obligations:

Here is the alleged difference: the Moral Impact Theory is “more thoroughly moralized than Dworkin’s theory”,^{Footnote 110} for it claims that legal content is the sum of the all things considered moral obligations we have in virtue of the action of legal institutions, whereas under Dworkin’s description “it seems likely that legal obligations will often diverge from moral obligations, even ex post ones.”^{Footnote 111} Although legal interpretation is constrained by the requirement of moral justification, it is equally constrained by the requirement of fit with existing legal practices, whatever these practices might be. If the principles underlying a given legal system are wicked, it would be possible to arrive at the moral conclusion that the content of the law is too wicked to be enforced or obeyed.

Nevertheless, this is not a correct understanding of the argument Dworkin developed in Law’s Empire. Dworkin does not claim that under Law as Integrity the interpreter might arrive at the conclusion that the law—or, to be more precise, what we call law when we use it as an interpretive concept—can be “too wicked to be enforced.” Dworkin used these words only to reply to the positivist position that he criticized. The fragment that Greenberg cited to distinguish his own theory from Dworkinian interpretivism is removed from its original context. In its original context, Dworkin explains a possible objection that one may adduce against the interpretive theory that Hercules—the imaginary judge who always decides legal controversies according to his model—would adopt. In Dworkin’s reasoning, the conclusion that the law might be “too wicked to be enforced” is not available to Hercules when he is acting in his judicial capacity. Instead, it is a typical assumption of the critic who thinks that Hercules is disingenuous because he is merely stating what the law should be, rather than what the law actually is in a given case.^{Footnote 112}

Greenberg’s analysis misses, therefore, an important point about Dworkin’s conception of interpretation. Dworkinian interpretivism, as Postema explains, is a theory that intends not only to fit legal practice as we know it, but also that “commands our allegiance because it portrays the law as serving a fundamental political ideal to which we are properly committed, namely, integrity.”^{Footnote 113} Interpretivism does not distinguish between the grounds of a law and its moral force. For Archimedean legal theories, the question of the moral force of legal obligations is separated from the question of the nonmoral determination of what these legal obligations are. But Dworkinian interpretivism “assumes no nonmoral prior accounts of grounds and leaves no residual question about whether legal obligations have moral force.”^{Footnote 114} If Greenberg were right, Dworkin’s theory of law would be Archimedean, not interpretive, since there would be cases with legal force that lack a moral force in the practical contexts in which we use a doctrinal concept of law. As Wil Waluchow admitted, shortly after the publication of Law’s Empire, this is not a fair reading of Dworkin. Here is the correct way to understand Dworkin’s overlap between the grounds and the force of law:

It is true that Dworkin claims in Law’s Empire that integrity would not be needed in a utopian society where all political decisions are morally perfect.^{Footnote 116} Integrity may require, for instance, that we “support a legislation that we believe would be inappropriate in a perfectly just and equitable society and to recognize rights that we do not believe people would have there.”^{Footnote 117} Nonetheless, this goes a long distance from saying that integrity would sometimes require that we come to the conclusion that legal and political obligations come apart in a particular political community where the associative obligations underlying the political value of integrity are in force. In such a community, on Dworkin’s view, governments and citizens alike recognize reciprocal obligations of equal respect and consideration.^{Footnote 118} Dworkin’s doctrinal concept of law is a concept we employ only in such communities, for it is only in this kind of polity that it makes sense to adopt the interpretive attitude towards the law that Dworkin’s model requires.^{Footnote 119}

On Dworkin’s view, the context of our arguments about the interpretive concept of law is an institutional context in which our concept of law is used in a justificatory way, with a view to identify our rights and duties. His normative point is that “we must interpret the law to make the best ‘moral’ sense of it.” As Guest explains, “we must always assume when we try to work out what the law requires or permits that it makes moral sense.”^{Footnote 120} There is an important political aspect of Dworkin’s theory of law that is missed if we describe it as a purely metaphysical theory.^{Footnote 121}

Legal argumentation, if Dworkin is correct, should take place on a sort of plateau of rough consensus that “if law exists it provides a [moral] justification for the use of collective power against individual citizens or groups.”^{Footnote 122} Although integrity demands that we respect communal decisions with which we may disagree, this demand only exists because our commitment to the associative obligations underlying integrity requires that we respect the decisions arrived at by a legitimate process. Unlike the mainstream tradition of legal positivism, Dworkin does not think that the question “what the law is” must be examined in a previous and independent way with regards to the question whether judges and officials must obey the law. These questions should not be regarded as separated, as if the validity of law were established in a purely factual way and the question whether we must or not obey the law were a purely moral concern.^{Footnote 123} One of Dworkinian interpretivism’s distinctive features is that legal concepts only can make sense if they are illuminated by moral considerations.^{Footnote 124} A theory of law, on Dworkin’s view, must be a theory of the legitimacy of the political power of legal institutions.^{Footnote 125-Footnote 126}

3.2. The Real Difference between the Moral Impact Theory and Dworkin’s Interpretivism

We are now ready to examine the most important contrast between Greenberg and Dworkin. This contrast does not consist in whether “legal rights” are enforceable upon demand, whether Dworkin’s principles justify “ex ante” our moral obligations in our political community, or whether we admit conflicts between legal and moral obligations. Rather, these distinctions only make sense because the kind of moral facts that Greenberg is considering are not interpretive moral facts as Dworkin understands them. Moral facts, on Greenberg’s view, are metaphysically prior with regards to legal practice, and there are no analogous entities in Dworkin’s accounts of law or morality. Although Dworkin sometimes speaks of moral facts,^{Footnote 127} he does not believe there are any noninterpretive moral facts. According to Dworkin, the only alternative to interpretation would be to assume the existence of moral realism and its implausible thesis that moral facts cause people to have moral convictions. Dworkin expressly rejects this assumption, which he designates the “causal impact hypothesis.” On this hypothesis, “moral facts can cause people to form moral convictions that match moral facts.”^{Footnote 128} But moral propositions, for Dworkin, “make no causal claims.”^{Footnote 129} According to Dworkin, the “causal impact hypothesis” is based on the mistaken assumption that moral facts are some sort of natural kinds, and Dworkin has strong views against this position. For Dworkin “there are no bare moral facts: moral reasoning … means drawing on a nested series of convictions about value, each of which could in turn draw on still other such convictions.”^{Footnote 130} Dworkin and Greenberg, therefore, have different things in mind when they talk about moral facts. Even though they agree that moral facts determine the significance of the social facts that purport to establish the content of the law, they think that moral facts are true or false in very different ways.

In the process of establishing the content of the law, there is an important worry that must be dealt with by any theory that upholds the One-System Thesis and regards the law as a subset of morality: the content of the law will always depend, at least in part, on the content of moral truths or moral facts. How do Dworkin and Greenberg deal with this problem?

Dworkin, as we saw at the first section of this paper, thinks that morality is a subject area in which there are no metaphysical tests to which we can appeal to check the truth of a given proposition. “Value judgments are true, when they are true, not in virtue of any matching but in view of the substantive case that can be made for them.”^{Footnote 131} There is nothing external from morality that could make something a true moral fact. It is in this sense that Dworkin conceives morality as an independent metaphysical domain. No metaphysical theory can be of any use to determine the content of moral facts, as we can read in the following excerpt:

Dworkin is skeptical about moral metaphysics because he is convinced that there is nothing in our world that can simply make a moral fact true or false. We must resort to interpretation precisely because there are no previous moral facts to match.

Greenberg, on the other hand, uses a different notion of moral facts, since these facts exist in a fundamental level. In his view, “we cannot figure out the content of the law without understanding how more basic facts make the legal facts obtain.”^{Footnote 133} Given his rejection of the Interpretive Thesis, he has to assume the existence of moral facts that our judgments are supposed to match.^{Footnote 134} If, as Greenberg suggests, Dworkinian interpretation is unavailable, then we need to find some other way to explain how moral facts obtain, and we can safely assume that there must be some metaphysical explanation for their existence.

Moreover, given that Law as Integrity does not admit the existence of non-interpretive moral facts that can be matched, Greenberg is not correct when he claims that Dworkin must resort to idealized principles to understand the content of the law. Interpretation, for Dworkin, is an argumentative process in which we test the consistency of our convictions on the basis of the principles that justify the practice we interpret. It is not correct to argue, as Greenberg does, that “jurisprudential theories like those of Hart and Dworkin offer accounts of how the content of the law is determined at the fundamental level”,^{Footnote 135} given that Dworkin probably would deny that there is any fundamental level beyond legal practice. Though this assertion might be correct about Hart, who advocates an Archimedean theory of law and subscribes to the Separability Thesis, it is definitely not for Dworkin. We cannot claim that moral facts determine the content of the law at some fundamental level while we advocate, as Dworkin does, a non-Archimedean theory of how not only legal, but also moral propositions can be true.^{Footnote 136}

Moral theories are made of abstract moral arguments that “are drawn from within morality”, in the sense that they are “themselves moral judgments.”^{Footnote 137} For Dworkin, when we stake a moral claim we do not apply second-order tests to determine the truth of the propositions we try to establish. What we have is neither an agreement about criteria nor a scientific process of verification. It is rather a special responsibility to try to “knit our values together” through interpretation.^{Footnote 138} Our moral epistemology, therefore, “must be integrated rather than Archimedean epistemology, and it must therefore be a substantive, first order moral theory.”^{Footnote 139} As interpreters, we are “morally responsible to the degree that our various concrete interpretations achieve an overall integrity so that each supports the others in a network of value that we embrace authentically.”^{Footnote 140}

In fact, it is Greenberg (not Dworkin) that appeals to idealized moral entities. In a recent paper in response to William Baude and Stephen E. Sachs, we can notice that even though Greenberg sometimes talks about legal interpretation, his notion of interpretation is very different from Dworkin’s constructive interpretation. Legal interpretation, for Greenberg, means the “activity of ascertaining what the law is”, not constructing legal propositions in a way that fits existing practices while coheres with its justifying principles.^{Footnote 141} On the Moral Impact Theory, “a method of interpretation is correct if it accurately identifies the legal facts.”^{Footnote 142} Although Greenberg—just like Dworkin—believes interpretation requires more than just “working out what the [legal] texts mean”,^{Footnote 143} his notion of interpretation is an intellectual process very different from Dworkin’s “constructive” interpretation. While Dworkin sees interpretation as a holistic and purposive activity in which one tries to read the law in the way that makes it the best it can be, Greenberg envisages interpretation as an inquiry in which we identify a law that is ultimately determined by some independent moral facts. “The role of interpretation is merely epistemic; that is, interpretation is just a way of figuring out what the law is.”^{Footnote 144} If one is looking for the justification of such moral facts, interpretation does not provide any answer. Hence, if we need moral facts to rationally determine the content of the law at the ultimate level, it is very hard to talk about moral truths without looking up to the ideal world.

Moreover, when Greenberg advocates that there are theoretical approaches that can be “upstream” or “downstream” of legal practices, he must be assuming that none of these approaches can be interpretive in Dworkin’s sense. He must be assuming that the principles or moral facts that lie upstream of the law must have some sort of ontological status, and fails to grasp the interpretive character of Dworkin’s project. The idea that interpretation has three-stages, which appeared in Law’s Empire, can explain why Dworkin’s interpretive theory is very different from this. According to Dworkin, we first identify a practice in the “pre-interpretive stage”, then settle on some “general justification for the main elements of the practice” in the second stage, by producing an “argument why a practice of that general shape is worth pursuing”, and then, if necessary, reform that practice in the “post-interpretive stage.”^{Footnote 145} Dworkinian interpretation is an abstract way to make a case for some moral truth. When Dworkin talks about truth, he means “to describe method, not metaphysics.”^{Footnote 146} He uses the concept of truth in the Peircean spirit, to refer to “what counts as a uniquely successful solution to a challenge of inquiry.”^{Footnote 147} We can “seek truth about morality”, he argues, “only by pursuing coherence endorsed by conviction.”^{Footnote 148} We test the truth of our moral claims in light of the other moral truths we already know and we try to make it part of the web of convictions we have. One of the reasons why Dworkin thinks that the doctrinal concept of law is a department of morality is because he thinks we also have such moral responsibility while interpreting a legal proposition in order to establish what rights and duties we, as members of the political community, are entitled to claim or obliged to fulfill.

The important point to compare Greenberg and Dworkin is not that each has a different metaphysical explanation of the nature of law (for Dworkin explicitly claims that he does not need such type of metaphysical explanation), but that their legal conceptions entail a different attitude in the process of fixing the content of the law. Greenberg’s Moral Impact Theory holds that at the fundamental level the content of the law is determined by moral facts. We must resort to moral facts in order to understand the significance of the legislative events that purport to alter the moral profile in our political community, given that these events must be rationally determined by something else. When we appeal to moral facts, we appeal to something external and independent from the practice of law. Dworkin’s Law as Integrity is different. First, while the Moral Impact Theory is an Archimedean theory of law, Law as Integrity proposes to explain the law from the internal point of view of the practice of law. Second, since for Dworkin the legal materials are “law” only in a “pre-interpretive sense”, the content of the law is determined by an integrative reading of the sources of law, in which these pre-interpretive materials constantly interact with the principles that provide their moral justification. We need interpretation because our legal propositions must be vindicated from within legal argumentation, which is a subset of moral argumentation. Our propositions about legal facts or moral facts are also substantive moral judgments. There is no fundamental level to which we can appeal.^{Footnote 149}

Greenberg is wrong, therefore, when he treats Law as Integrity as a metaphysical explanation of the foundations of law, because this reading is incompatible with the Interpretive Thesis. Greenberg’s Moral Impact Theory of Law is what we get when we abandon Dworkin’s theory of interpretation and try to retain the One-System Thesis. If we reject the Interpretive Thesis, we cannot continue to insist on the One-System Thesis unless we are prepared to hold that there is some metaphysical test to establish the truth of moral facts. If we adopt Greenberg’s theory of law we will end up being forced to admit, at an abstract level, that such metaphysical test is somehow legally binding, since we must apply this test to identify the content of the moral facts that partly determine the content of legal obligations.

4.1. Natural Law Jurisprudence without an Ethical Theory?

The Moral Impact Theory is a form of natural law theory of the determination of law.^{Footnote 150} Nonetheless, it is a peculiar form of natural law jurisprudence, since it lacks an ethical theory and refuses to discuss any principle for explaining the foundation of the moral facts which are needed to determine the content of the law. The Moral Impact Theory lacks an account of values and practical rationality; it purports to be ecumenical about this matter: although it asserts that moral facts are required to determine the content of our legal obligations at the most fundamental level, it argues that any moral theory can do the work of explaining the root of such moral facts. To be more specific, the Moral Impact Theory is a form of natural law jurisprudence in the sense of Mark Murphy’s account of natural law theories, inasmuch as it claims that there is a “positive internal connection between law and decisive reasons for action.”^{Footnote 151} The enactment of a given statute, for instance, must give rise to “genuine obligations” in order to make a contribution to the content of the law.^{Footnote 152} Nonetheless, the Moral Impact Theory is not, and makes no appeal to, a natural law theory of practical rationality, which intends to elucidate the “basic goods” that constitute the “fundamental reasons for action.”^{Footnote 153}

Although I do not dispute Mark Murphy’s claim that a natural law jurisprudence can be “independent of the central theses of the natural law account of practical rationality”,^{Footnote 154} I find it odd to support a natural law jurisprudence entirely indifferent to any sort of ethical theory. Greenberg is probably the first historical example of a jurisprudential theory of this kind. Even if it is true that an account of natural law jurisprudence can be logically independent from a natural law account of practical rationality, it is hard to see how the former could be a sound theory of natural law, given that it fails to identify any “conditions and principles of practical right-mindedness.” As John Finnis explains, “a sound theory of natural law is one that explicitly, with full awareness of the methodological situation just described [i.e., of the need to select a “practical point”], undertakes a critique of practical viewpoints, in order to distinguish the practically unreasonable from the practically reasonable, and thus to differentiate the really important from that which is unimportant or is important only by its opposition to or unreasonable exploitation of the really important.”^{Footnote 155}

Given Greenberg’s claim that the content of the law always depends on the content of moral facts, it should be natural to expect him to believe in moral objectivism, even if it is not the strong sense of moral objectivity required by a typical natural law account of practical reasonableness. If we fail to establish the objectivity of moral facts, it is not clear how these facts can be able to determine the significance of the legislative events that constitute the social determinants of the law. We need objective moral facts if we consider that it is important that the law is determined in an objective way. In this sense, Kenneth Himma argued that Greenberg’s rational intelligibility requirement implies, by a reductio ad absurdum, the truth of moral objectivism. One of the implications of the rational intelligibility requirement is that “law is not possible if there are no independent value facts”,^{Footnote 156} and this assertion, in turn, implies that if we grant the existence of law we must accept the premise that value facts must have an independent and objective existence.^{Footnote 157}

In spite of Himma, Greenberg claims that the argument in How Facts Make Law is based on considerations that are “metaphysical in character and do not involve normative or meta-ethical claims.”^{Footnote 158} He sustained in response that his account of the role of moral facts in determining the content of the law can be neutral vis-à-vis the meta-ethical justification of normative facts, for it intends “merely to offer a common, plausible and relatively non-committal account of value facts.”^{Footnote 159} It need not take issue with any particular meta-ethical theory, for it is compatible even with a subjectivist or a non-cognitivist theory of morality.^{Footnote 160}

Greenberg believes that different people can uphold very different accounts of moral facts and yet agree about some requirements of moral facts or, more specifically, about how these facts play a part in determining the content of the law. To give an example, although a utilitarian, a libertarian, an egalitarian and, perhaps, even an advocate of moral subjectivism or some sophisticated version of non-cognitivism might diverge about the concept of democracy, they might still converge on the proposition that democracy requires fidelity to written statutes, in such a way that some interpretive techniques like traditional forms of originalism are not appropriate methods to determine the content of the law. Though the supporters of these accounts of moral facts strongly disagree about what makes something a valid moral fact, they are likely to agree that democracy, fairness and equality (or perhaps other fundamental values) require us to rationally determine the content of the social facts that are designed to make the law in a similar way. The Moral Impact Theory does not need to offer a complete account of the foundation of moral facts, since it is satisfied with an explanation of how moral facts ultimately determine the content of the law.

Nonetheless, this is not a satisfactory explanation of the objectivity of law. There is a flip-side to the account of moral facts that appears in Greenberg’s response to Himma, which leads to unwanted consequences for the process of determining the content of the law. If, for instance, we admit a non-cognitivist or a subjectivist conception of moral facts, the Moral Impact Theory faces the risk of attributing a serious degree of indeterminacy to the content of the law. Given that moral facts always play at least some role in determining legal facts, we need a measure of moral objectivity in order to arrive at objective legal facts. If we adopted Greenberg’s theory, we would always face the risk of turning the difficulties that moral non-cognitivism and moral subjectivism face in their explanation of morality into legal difficulties. Whatever is the type of indeterminacy we ascribe to a moral fact, we can easily imagine cases in which such indeterminacy is transferred to the content of the law, since the determination of the relevant moral facts is part of the judgment we make to identify the law. It is not obvious that we can achieve, without a convincing account of the objectivity of moral facts, the kind of accuracy that Greenberg believes we need in order to provide a plausible method of legal interpretation.^{Footnote 161} For example, if we suppose that democracy is an empty concept or lacks an objective content, as a skeptic might believe, how could we hold that democracy excludes an appeal to legislative intentions or any other interpretive resource? If we cannot know what democracy is and why it is objectively important, how can we claim that democracy (or any other value) plays a part in the process of determining the content of the law? It is difficult to imagine how a theory which argues that the content of the law is rationally determined by a moral fact can be indifferent about the meta-ethical principles that we have to apply in order to ascertain this moral fact. If there are no objective moral facts, it is hard to demonstrate how there can be any objective legal facts.

I cannot find any reason, therefore, to adopt any version of the One-System Thesis without either a natural law account of practical rationality or, if this turns out to be unavailable, at least an interpretive or procedural conception of moral truths. Since the Moral Impact Theory accepts neither, I cannot find any reason for accepting it as a plausible theory of law and legal interpretation.

4.2. Greenberg’s Defense of a Version of Strong Natural Law

Just like Dworkin, Greenberg believes that legal practices are “brute facts” that must be rationally determined by a moral fact. Dworkin called these practices “law in a pre-interpretive sense” precisely because he thinks that we need a moral judgment to understand the content of the law.^{Footnote 162} But there is also an important difference. While Dworkin thinks there are no pre-interpretive moral facts, Greenberg must accept the existence of some independent moral facts.

I think that this difference has serious implications for the Moral Impact Theory of Law. It makes it a form of natural law much more demanding than other versions of natural law, such as, for instance, Finnis’ jurisprudence. Under the Moral Impact Theory, the content of concrete legal norms will be determined neither by an interpretive moral judgment, as Dworkin advocates, nor by an authoritative enactment, as legal positivists and most natural lawyers maintain. On the contrary, it will be partly determined by metaphysically prior moral facts.

My main worry is not about what Greenberg actually says about moral facts. Instead, it is about what he allows others to say about the truth of a legal proposition. Consider, again, the case of natural law theories. We all know that a theory of natural law, as John Finnis says, “claims to be able to identify conditions and principles of practical right-mindedness, of good and proper order among persons, and in individual conduct.”^{Footnote 163} What we do not know in most theories of natural law, including Finnis’ account, is how we can metaphysically demonstrate the principles that these theories purport to reveal. When Finnis explains his “basic” goods or values, he claims that they are “self evident, obvious”, and admits that they “cannot be demonstrated, but equally need no demonstration.”^{Footnote 164} Could Greenberg do a better job? The only answer I can find is: “we do not know”, since we are still waiting for his metaphysical explanation for the foundation of moral facts.

The problem is not only that Greenberg lacks a proper metaphysical theory for determining moral facts, but the political consequences of his theory of law. Unlike most contemporary natural lawyers, Greenberg is not satisfied with only a “weak version” of natural law jurisprudence. According to the “weak” natural law thesis, “law that is not backed by decisive reasons for compliance is defective as law”,^{Footnote 165} but this alone is not a ground for stripping a norm of its legal character. Weak natural lawyers, therefore, do not support the One-System-Thesis. Unjust laws are defective because they fail to satisfy an important claim to legitimacy that legal enactments necessarily presuppose, but we cannot infer from this failure that such laws are not valid and enforceable by a legal authority. In effect, proponents of a weak natural law jurisprudence are usually based on a natural law argument about practical reasonableness, for they assume that the principles of natural law “justify the exercise of authority in community”, according to the “manner conveniently labeled as the Rule of Law.”^{Footnote 166} John Finnis, for instance, in the most sophisticated contemporary account of natural law, defines authoritative pronouncements as “exclusionary reasons” in the sense of Joseph Raz,^{Footnote 167} such that an act is authoritative “if and only if one treats it as giving one sufficient reason for believing or acting in accordance with it notwithstanding that one cannot oneself see good reason for so believing or acting.”^{Footnote 168} The principles of natural law are not meant to be balanced against authoritative pronouncements. Rather, they provide the grounds for authoritative government and co-ordination towards the common good. The “point of jurisprudence”, according to Finnis, “is to explain certain human institutions by showing how they are responses to the requirements of practical reasonableness.”^{Footnote 169}As Waldron explains, Finnis’ account of natural law is a “natural law account of positive law”, which provides us with the basic values that justify authority and “produce a set of moral criteria for evaluating positive law.”^{Footnote 170}

Greenberg follows a very different track. He comes close to the “strong” version of the natural law thesis, which holds that if a positive law is inconsistent with our moral obligations we must infer that such positive law is not part of what we call “the law” in a proper sense. If a statute or some other authoritative material is not “backed by decisive reasons for compliance”, then the strong natural law thesis tells us that we should not recognize this authoritative material as legally valid.^{Footnote 171} The only difference we can find between the strong version of the natural law thesis and the Moral Impact Theory is that while the former is supposed to apply to all possible legal systems, the latter is true only for the legal systems to which it applies (i.e., to legal systems that are sufficiently legitimate to be able to generate genuine obligations). Thus, “the Moral Impact Theory has a consequence that is roughly equivalent to the strong natural law thesis, but with limited scope.”^{Footnote 172} In the ordinary application of law in the legal systems to which the Moral Impact Theory applies, which Greenberg takes to be our legal systems, the strong natural law thesis is part of the explanation of the content of the law.^{Footnote 173}

We should be worried, therefore, with the political consequences of the Moral Impact Theory, given that any theory of law must deal not only with the question of determining the “identity” of the law, i.e., with “what it is about” law that makes it “the law”, but also with what Scott Shapiro calls the “Implication Question”, which concerns “what necessarily follows from the fact that it [the law] is what it is an not something else.”^{Footnote 174}

Every dispute about the concept of law, as the Hart-Dworkin debate illustrates, has relevant political consequences that follow from the methodological decision of determining the practical viewpoint to be adopted in the description of the law.^{Footnote 175} A debate about the concept of law should not be regarded as morally neutral insofar as it “reflects a substantive disagreement about the best—the politically best—way to conceive law and its boundaries.”^{Footnote 176}

We can notice, at this point, that even though Greenberg presents his Moral Impact Theory of Law as a variant of “strong natural law jurisprudence”, he equivocally believes that his theory is just a neutral description of legal activity. He seems to replicate the same mistake that Hart made in the Postscript to the second edition to The Concept of Law, where he argued that his theory is “descriptive in that it is morally neutral and has no justificatory aims.”^{Footnote 177} Just like Hart, Greenberg fails to see that his own theoretical work—like any theoretical work in jurisprudence or social science—is “controlled by the adoption”, quite often “on grounds left inexplicit and inadequately justified”, of “some practical viewpoint as the standard of relevance and significance in the construction of his descriptive analysis.”^{Footnote 178}

When the Moral Impact Theory of Law combines the One-System Thesis with the rejection of the Interpretive Thesis and a silent attitude towards the objectivity of morality, it opens a very dangerous road, as we can illustrate in the following example. Suppose Jane and Mary live together in the same polity and have a strong sense of respect for community values, although each has a different doctrine about the nature and the foundations of moral principles. Jane is a devoted Christian and accepts Finnis’ account of the “basic values” that define our common good, whereas Mary is a member of a socialist party and a strong supporter of “women’s rights.” Suppose they both take up jobs as judges in the same county. If they follow Finnis, who admits only a weak version of Murphy’s natural law thesis, they will accept Aquinas’ view that it is up for the legitimate political authorities to do the activity called determinatio, which is the process of specification of the legislative alternatives left open to positive laws. They will think that “issues of justice or injustice of the determinatio are pushed to the margins of the legal domain”,^{Footnote 179} and will accept a concept of “legal validity” similar to that of legal positivists, inasmuch as they agree with Finnis that “natural law theory has no quarrel with—indeed promotes—a bifurcation between intra-systemic [legal] validity (and obligatoriness) and legal validity (and obligatoriness) in the moral sense.”^{Footnote 180} Even though each may have her own views about gay marriage, abortion, euthanasia, gender, sexual morality, pornography, hate speech, praying at public schools, public financing of religious institutions, and so on, I can reasonably expect that in spite of these views they will abide by the positive laws as they are identified by something analogous to Hart’s rule of recognition. Weak natural law jurisprudences are theories about the justification of authority, so the content of valid law is ultimately determined by authority, not by a second-order moral fact.

What would happen, however, if Jane and Mary reject the weak version of natural law jurisprudence and adopt something like Greenberg’s explanation of the way moral facts determine the content of the law? Would they feel morally compelled to follow the legislative decisions that stem from the action of political institutions? Even though I (along with most people) believe this is what they should actually do, there is no guarantee that everyone else will have reasons to do the same. They will not have any standard against which they could test their moral intuitions. Without any ethical theory and without the Interpretive Thesis, which attributes to interpreters a moral responsibility of equally respecting not only everyone’s view in the community, but also the institutional history of such community, they might feel tempted to treat their moral preferences as if they were objective moral facts. Mary, for instance, is very likely to think that abortion is a fundamental legal right, and perhaps she feels disgusted by the U.S. Supreme Court’s case law about the First Amendment, when it comes to the permission of pornography and gender-sensitive publications. As strong natural lawyers, in Murphy’s jurisprudential sense, both Jane and Mary might be unsatisfied with the political values underlying the laws of their community; they might appeal, instead, to external values that should be accepted at some pre-political fundamental level.

Jane might think, as some decent people in our society do, that it is her duty to enforce the substantive values that define our common good, and that some of these goods are so important that they often override wrong political decisions of democratic assemblies. Perhaps she might also be impressed by Jason Brennan’s recent book and think that democracy is the rule of the stupid,^{Footnote 181} so it should not figure amongst the ultimate moral truths that determine the content of the law. Perhaps Mary reasons in a similar way, although in the opposite direction. Perhaps, in an extreme case, the only assumption they share in a contested case is the argument of Brennan’s book. In that case, it is very likely that both Jane and Mary will appeal to their own abstract moral values as the primary source of their judgments about the significance of the actions of legal institutions. They might think, for instance, that what statutes and precedents say are only ancillary sources of the content of the law. Even though Greenberg would not subscribe to these views, there is nothing in the Moral Impact Theory that can stop them from understanding values in that way.

We should worry, therefore, about the political consequences of Greenberg’s account of the grounds of law. As Liam Murphy explains, in every debate about the determinants of legal content there is a “political dimension” about the “place of moral and political considerations in the grounds of law”, which “matters more than any purely intellectual concern we might have.”^{Footnote 182} What the Moral Impact Theory of Law would tell you if you subscribe to one of the views that I stated above is that “the master question is what is morally required in light of the enactment of the statute, not what the statute’s linguistic content is”,^{Footnote 183} and that the contribution of a statute to the content of the law will depend on the “on-balance best resolution of conflicts between moral considerations.”^{Footnote 184} All I can do is hope that you achieve the right balance between what the statute says and your own personal moral views.

If, on the contrary, you—or, in our example, Jane and Mary—accept Dworkin’s interpretive theory of law and morality, we get a very different picture. Dworkin wants a non-Archimedean or internal theory of law because he thinks that we cannot step outside legal practice in order to understand the law. The content of the law, for him, depends “not on special conventions or independent crusades but on more refined and concrete interpretations of the same practice it has begun to interpret.”^{Footnote 185} Participants of this practice share the interpretive attitude and responsibility towards their fellow citizens that their justificatory roles entail. Once you accept this responsibility, you will tend to accept also his interpretive principle that no government can be legitimate unless its laws and policies “can reasonably be interpreted as recognizing that the fate of each is of equal importance and that each has a responsibility to create his own life” (which includes the individual responsibility of making the ethical judgments about how to live one’s life).^{Footnote 186} If we lose this sense of political responsibility, which follows from his interpretive approach, we turn Dworkin’s liberal theory of the legitimacy of law into a dangerous version of strong natural law.^{Footnote 187}

Greenberg’s non-interpretive version of the One-System Thesis makes the content of the law always dependent on an external judgment based on a second-order moral fact. Moral metaphysics drives legal argumentation, given that the beginning of our reasoning about legal facts lies on fundamental moral facts that also stand in need of a metaphysical explanation.