This collection of thirteen chapters deals with various facets of Kant’s doctrine of the highest good and arose from a conference at the Goethe University, Frankfurt am Main, in September 2013. Its explicit purpose, as stated in the Introduction, is to ‘take a nuanced perspective on Kant’s doctrine of the highest good – a perspective that not only provides us with a more authentic picture of Kant’s moral philosophy but also highlights the various philosophical problems with which the doctrine is concerned’ (p. 2). Using ‘perspective’ in the singular is a bit misleading since the collection on the whole delivers quite diverse perspectives on wide ranging topics related to the highest good. That said, the collection’s strength lies to a great extent in its quasi-conversational organization between perspectives – an arrangement that offers much food for thought to those who focus on this polarizing aspect of Kant’s philosophy.

The first part, comprised of five chapters, takes on various (mostly familiar) puzzles dealing with the highest good within Kant’s moral theory (e.g. questions of whether it is in fact a duty to promote it and of how to interpret happiness in a non-contradictory way with respect to Kant’s strict formalism, etc.). The second and third parts, both consisting of four chapters, expand to encompass themes ranging from those closely linked to the highest good (i.e. the postulates) to those less so (e.g. the connection between the highest good and teleology). Without the ability to delve into each contribution in a fruitful and fair manner, I will instead attempt to highlight contributions I find worth special attention as representative of the collection’s express purpose, namely, illuminating nuances of the highest good.

In Part I, Pauline Kleingeld’s contribution stands out as a strong account of why it is a duty to promote the highest good. She argues that one must understand it as directly arising and aligning with Kant’s discussion of the good in the Analytic, which provides the key for making sense of why it is morally consistent to include happiness as part of the highest good. Happiness is not good because it is agreeable, but because it is ‘morally good’, which follows not from its status as an object, but rather ‘if and only if it is morally allowed to will it’ (p. 37). This contribution is further strengthened by Kleingeld’s ‘philosophical (re)construction’ of a direct duty to promote the highest good as something that ‘goes beyond’ the categorical imperative. Her reconstructed argument is not only enjoyable (her metaphor of instructions for building a bicycle is highly entertaining, while simultaneously elucidating) but also a fine example of the history of philosophy providing fertile ground for one’s own philosophical powers coming to the fore.

Florian Marwede’s contribution offers an indirect response with a discussion of how an emphasis on happiness can be reconciled with Kant’s ethics by attempting to ‘derive a duty from the categorical imperative that is directed at our own happiness considered as a part of universal happiness’ (p. 51). Overall, Marwede’s attempt is ambitious as it seeks to make sense of how striving for one’s own happiness is consistent with Kant’s moral theory as a whole. For those who are very much concerned about the role of happiness in Kantian ethics, Marwede’s piece is worth reading if not (depending on one’s point of view) for insight, at least for a rich point of contrast. Ultimately, his well-argued piece left me unconvinced, however, since I think it is constructed over an unstable, philosophical fault-line. As I read him, the duty to promote one’s own happiness ‘only as part of universal happiness’ (p. 63) rests on a notion of happiness that is sufficiently robust vis-à-vis the individual (i.e. one that is not reducible to moral happiness, see p. 53) as well as one that ‘converges completely with the end of universal happiness’ (p. 61). The combination of these two factors leads to a ‘specific way’ of ‘pursuing one’s own happiness as part of universal happiness’ which ‘transforms the content of my pursuit’ (p. 66). The change in content consists in the fact that ‘I make other people’s ends my own, thus finding part of my own happiness in their achievement of their ends and in their becoming happy’ (p. 66). However, this seems an unstable foundation for combination of happinesses since it seems to make my happiness dependent on our universal and unconditionally shared ends (which would seem to force my happiness into conformity with others). In short, I could not easily grasp what would make an instance of happiness constitutive of or non-constitutive of universal happiness. Perhaps if Marwede had more space to spell out how personal happiness converges with this notion of universal happiness, I would be more willing to go along with his suggestions.

If one thing unifies the various contributions of Part I, it is their orbit around an ostensible tension or dualism lying at the heart of the concept of the highest good by including personal happiness as a key component. For this reason, Stephen Engstrom’s contribution stands out and pairs well with the previous contribution by Kleingeld. His central claim is that there is in fact no dualism lurking within the concept of the highest good; indeed, the material condition (happiness), by remaining conditioned on the unconditioned good (virtue), results in happiness being nothing other than the material taken up in practical reasoning as ‘happiness resulting through that very cognition’s production of it’ (p. 107). Happiness becomes not something diametrically opposed to virtue’s purity, but rather the necessary material element in practical reasoning taken up and transformed via the good will into ‘good conduct’ (p. 107). Out of Engstrom’s argumentation, a picture emerges of the highest good that, while novel in a way, tastes very much like Kant’s own cooking. Human happiness in human life requires the sort of ‘self-production through knowledge’ that is characteristic of our willing in general (p. 101). And though the happiness receives its form from practical cognition in a universal sense, it remains a condition that is anchored in humanity’s physical and psychological nature. Hence, Engstrom’s interpretation provides compelling mirroring to theoretical reasoning in that, ‘Even though the form determines the matter, it nevertheless depends on it’ (p. 103). With such a complex and detailed contribution, one cannot do it justice in a review slogan. Before moving on, however, it must be pointed out that this contribution is a must read because of the case it makes for the highest good forming the Groundwork’s point of origin. Indeed, against those who hold that the ‘practical relation’ between the two constituent concepts of the highest good receives only ‘abstract description’ in the second Critique, Engstrom argues a strong case for a robust and fleshed-out description standing front and centre in the Groundwork (and not in the form of the later formula of humanity as a kingdom of ends). Engstrom’s work, while clear, is quite dense; it provides one, though, with new outlooks on terrain that one thought familiar.

Turning now to Part II, which focuses primarily on the postulates of practical reason, Stephan Zimmermann’s contribution presents an intriguing account for understanding the sort of ‘objective reality’ that Kant ascribes to the postulates of pure practical reason. Zimmermann carefully exposes how the method of thinking by analogy (in contrast to ‘inference from analogy’, see pp. 144–5) must be the key to understanding how the postulates elevate ideas of reason to the level of objectively real objects for practical reason. Because of their practical necessity (arising from the fact of our freedom made conscious by the moral law), we further think of these ideas from a practical perspective ‘as if they existed like [sensible objects]’, but in a way that we can reasonably refer to on Zimmermann’s reading as ‘noumenal objects’ (p. 153). His account I found plausible throughout, though he sometimes employs too many questions that eventually one finds he probably meant rhetorically.

Paul Guyer’s contribution provides great insight into the influence of Mendelssohn’s Phaedon on Kant’s arguments regarding the immortality of the soul. Guyer’s thesis is that Kant ‘adopts Mendelssohn’s argument for the case of happiness’ in the first Critique, ‘while in the second Critique he rather adopts it for the case of virtue’ (p. 162). Focusing on the development of Kant’s ideas in his later works, Guyer thinks the notion of our moral perfection transfers from the continuation of the individual to the continuation of the species. I am fully on board with this thesis. However, while I agree that the immortality of the soul plays a diminished role in the later works, I do have a reservation about taking it to the extreme that Guyer wants to claim: namely, that the immortality of the soul becomes moot as soon as the Religion because Kant thinks that ‘complete conversion’ (p. 171) to a fully moral disposition is something ‘any human being can achieve at any time’ (p. 170). My reason for reservation is that the passage he grounds this claim on seems to provide ambiguous evidence, especially since it underlines our deeds as remaining ‘always … defective’ and our ‘disposition’ as being thought of as part of an ‘infinite progression of the good towards conformity to the law’ (Rel, 6: 67). Moreover, there is Kant’s assertion that ‘notwithstanding [a person’s] permanent deficiency, a human being can still expect to be generally [überhaupt] well-pleasing to God, at whatever point in time his existence be cut short’ (Rel, 6: 67, first emphases mine). While one could try to read it as Guyer does, one is I think equally justified in reading it as a statement that we in fact cannot ever be certain that we are morally perfect. Although we may still think of ourselves as being ‘generally well-pleasing’ in our attempts to perfect ourselves morally, this is not the same as being completely well-pleasing. As a result, Kant’s references to an infinite progression still seem, to me at least, open for use in arguments for the immortality of the soul from the agent’s perspective. Regardless of how one interprets this passage, Guyer’s piece is provocative and important for further debate.

Part III begins with Thomas Höwing’s contribution, attempting to solve an alleged ‘puzzle’ in Kant’s defining the three major forms of assent (Fürwahrhalten). The puzzle, Höwing thinks, arises in that belief is described as sharing one ‘justificatory feature’ with knowledge (namely, subjective sufficiency) and one with opinion (namely, a lack of objective sufficiency), and yet ‘this seems to run counter to Kant’s central claim that Belief has at least one unique feature – it requires non-epistemic justification’ (p. 202). This contribution contains much promise and is very welcome since it undertakes an under-researched project: namely, researching our epistemic relation (i.e. the form of our assent) to the highest good. I would like to highlight, however, two slight issues. First, the puzzle seems to me questionable unless one grants Höwing’s assumption that ‘[w]e simply cannot have both’ a solution that retains the terminological distinction and that allows for the unique function to be included in some way (see p. 207). On my reading, Kant’s ‘central claim’ seems to posit precisely the opposite. It sets the special feature of belief in explicit connection with other ‘theoretically insufficient’ forms of assent. In short, Kant allows that not all cases of objective insufficiency are created equal. Consequently, this lack of equality invites further sub-categorization without risk of conceptual inconsistency. The second issue is Höwing’s treatment of the secondary literature. In particular, Höwing asserts that Andrew Chignell’s (Reference Chignell2007a, Reference Chignell2007b) and Lawrence Pasternack’s (Reference Pasternack2011a, Reference Pasternack2011b, Reference Pasternack2014) taxonomies of Kantian assent, ‘[r]ather than dissolving the puzzle’, are ‘somehow built around it’ (p. 207). First and foremost, I think this is most likely due to the puzzle not residing where Höwing thinks it does, and as a result, not being central to Chignell’s and Pasternack’s interpretations. Beyond this point, however, the way he presents Chignell’s ‘interpretation’ seems a bit too superficial; and Pasternack’s position seems misunderstood.Footnote ¹ Though Höwing offers caveats, his exposition of the relevant secondary literature seems off the mark: a point that distracts from his otherwise creative exegesis.

Marcus Willaschek’s contribution on whether belief in the realizability of ends in relation to the highest good is a valid principle is a great study of, in Willaschek’s terms, the ‘realizability principle, or RP’ (p. 223). Maintaining the validity of this principle – which goes through multiple variations, but is ultimately always the notion that one can only rationally pursue an end that one also believes to be realizable by oneself – becomes the main task. Willaschek’s defence of it against three objections, which he ultimately replies to with the same move, leads to an excellent investigation of the difference between practical possibility qua ‘doing’ and qua ‘trying’ (pp. 238ff.). We come to see that the RP must evolve: ‘In particular, rationally trying to realize some end does not in general presuppose that one believes that one’s end can be realized. … But rationally trying to realize some end requires that one does not believe it to be impossible to realize one’s end’ (p. 241). This ‘result’ presents a more complex version of the RP that seems better suited for the more nuanced positions he references in the third Critique and On the Common Saying.

The closing of the collection is a very happy one. Günter Zöller’s piece constitutes an odyssey from a bird’s eye view that takes the reader in a quick but crystal-clear exposition of how teleology moved historically from Aristotle to Kant, and then became the explanatory key to unlocking Kant’s dual portrayal of theoretical and practical reasoning. Ultimately, it ends with a discussion as to how the ‘cooperative constellation’ (p. 269) of the two functions of reason comes to form the highest good while ‘salvaging metaphysics from remaining void and empty’ (p. 278). Although the pace is sometimes dizzying, one never feels lost as Zöller pieces together how the highest good changed with the introduction of the purposiveness of nature in the third Critique and in the Progress essay. In these works, the highest good becomes a practically necessary object that in turn anchors ‘God, morally successful freedom and human self-survival’ into ‘self-made objects of human reason to which an ontological status of sorts (“objective reality”) is granted “freely” (freiwillig)’ (p. 278). Zöller’s contribution shines light on an area that deserves much more in-depth study, namely, how Kant’s thinking on teleology became enmeshed with the doctrine of the highest good. As the final chapter of the collection, this contribution points the way forward for future research on the object of our moral willing – namely, into the terrain of Kant’s later and lesser studied works after the principle of purposiveness became part of his transcendental enterprise.