For many years scholars have wondered who was the intended audience of Justin's Dialogue with Trypho and, related to this, what was the intended purpose of this very long, repetitive and, some would say, poorly structured work. In the published version of a University of Chicago dissertation, written under the guidance of Margaret Mitchell, Matthijs den Dulk adds his voice to the debate.

In nuce den Dulk argues that the Dialogue was written for an internal audience and that while Justin was not uninterested in arguing a case against non-Christian Jews, even convincing them that they should convert to Christianity, he also had in his sights the claims and opinions of what he (den Dulk) terms demiurgist Christians, that is, Christians like Marcion, who claimed that the creator God witnessed in the Old Testament was to be distinguished from an ultimate and absolute deity made manifest in Christ. Justin argues such a case at a time when rival Christianities competed with each other and Christianity remained in flux. The Dialogue becomes not only an attack upon demiurgical forms of Christianity but also a call for their exclusion. In attempting to achieve this aim, Justin also argues for an heresiological form of Christianity, which was not yet an established form of discourse. ‘Construed in this manner, the Dialogue emerges as a surprisingly rich and inventive text that is doing much more than offer[ing] a straightforward presentation and defence of Christianity over against Judaism’ (p. 8).

Den Dulk argues his case over five chapters. Chapter i establishes how deeply committed Justin was to opposing demiurgical Christians. They appear as important in the argument of Justin's 1 Apology where Justin attempts to exculpate Christians of charges of criminality by attributing the same to the demiurgists and encouraging their persecution. Den Dulk also argues that Justin's Syntagma, a work that is no longer extant but is mentioned by Irenaeus, concentrated its attack upon demiurgical Christians. Chapter ii argues the case for an internal audience for the Dialogue, concentrating on passages which seem to assume such a thing (for example, Dialogue 35, where a number of Christian heresies are mentioned) and on the practical issue of how such a long work could have been distributed beyond Christian circles. In chapter iii den Dulk shows how in the Dialogue Justin undercuts the teaching of his demiurgical opponents. Many of the arguments with Trypho, particularly as these related to the contents of the Old Testament, are repeated in Irenaeus’ Adversus haereses and in Tertullian's Adversus Marcionem. Den Dulk also draws attention to places in the Dialogue where Justin appears to be responding to arguments employed by demiurgical opponents rather than non-Christian Jews. Chapter iv attempts to show how many of the oddities which scholars have recognised in the Dialogue as these relate to Justin's and Trypho's interactions – the strongly polemical tone of Justin; Trypho's agreement with many of Justin's arguments; and the failure of Trypho and his friends to be converted at the end of the work – all make sense if demiurgists are being addressed. The latter, in particular Marcion, made use of Jewish unbelief to support their views – after all if the Old Testament had predicted Jesus, then surely the Jews would have converted? Justin counters this by showing that Jews agreed with Christian arguments as these related to Scripture but their obduracy prevented them from converting (hence the failure of Trypho and his companions to convert at the end of the work). Other elements of the work also make sense against this background – the philosophical introduction focuses on Plato because of Plato's interest in a demiurge; and reference to the Bar Kokhba revolt is best explained by noting how defeat in the Jewish revolts was used by demiurgists to prove the inferiority of the Jewish God. The final, and possibly most involved, chapter attempts to show how Justin seeks to justify an heresiological approach as well as playing down the importance of the presence of division among Christians, in part by showing that divisions among Jews are worse (here the famous list of Jewish heresies in Dialogue 80 is thought to be fictitious).

This is an interesting book from which one can learn something whether in agreement or disagreement with its thesis. It would require a much longer review than is possible here so just a few points will have to suffice. At a general level den Dulk never quite comes clean on the balance that he perceives between the book as one aimed against Jews and one aimed against so-called demiurgists. The latter is described at one point as ‘an important aspect of the work’; at another as affecting the Dialogue's argument ‘to a significant extent’. Elsewhere the Dialogue is described as being used to continue his campaign against demiurgical Christians, and the demiurgical thesis is thought to explain ‘various key aspects’ of the Dialogue. At pp. 87–8 den Dulk makes it plain that Jews are in his sight (‘Justin likely did want to convince as many Jews as possible of his point of view’), and that if more Jews could be convinced, then demiurgical positions would have less purchase. The dual aims converge, and it would be wrong to create a dichotomy between them. But one might be led to believe that one aim was subservient to the other (for example, the way in which the document presents Trypho and his friends seems framed by the demiurgical problem, if one might put it that way). Secondly, I sometimes sensed that the tail of the thesis was wagging the dog of the text – to explain the philosophical section of the Dialogus by reference to the demiurgical difficulties that Justin is facing seemed an odd reading. After all, the demiurge, as presented by Plato in the Timaeus, is not the subject of the old man's complaint in the last section of the philosophical introduction; and the view that the significant presence of Bar Kokhba in the Dialogue is best explained by reference to a perceived criticism of the demiurgists of the Jewish God is based on nothing more than a disputed passage in Irenaeus – in fact its presence is better explained by reference to the Jewish-Christian context, assumed by Justin, not least because there is an immediacy to the subject, as Judith Lieu pointed out in the relevant section of her Image and reality. Thirdly, while den Dulk is right to point up oddities in some of the things that Justin asserts in relation to his ostensible subject (Jewish-Christian argument) and to argue that these appear as intrusions in the text, it seems wrong to place as much importance on these texts as he does. The reference to Christian heresies is hardly frequent (when den Dulk talks about a ‘considerable number of instances’ of demiurgical references, he is exaggerating); and the passages highlighted by den Dulk appear as intrusions precisely because the bulk of the material is pertinent to arguments between a Jew and a Christian. I do not doubt that on occasion arguments touching upon discussions with demiurgical opponents may have intruded into Justin's mind when writing the Dialogue (and this book makes a good case for that) but this is not as important to Justin as arguing his case against non-Christian Jews whose importance for Christians was clear outside of an assumed demiurgical context. In this context it should be noted that when den Dulk argues for the importance of demiurgical Christians for Justin by indicating their presence in 1 Apology, he fails to observe the greater significance of Jews in 1 Apology, indicating the degree to which they intruded upon Justin's anxieties. Finally, that arguments adversus Marcionem converge with arguments adversus Judaeos, as these related to Scripture, is not in itself a strong (or indeed a surprising) point, not least when we do not know how Justin argued the former case – indeed, if he had argued against the Demiurgists in the Syntagma, a moot point, of course, why would he have needed to argue his case again in the Dialogue, and have done so in such a concealed way? Tertullian, after all, could write both a work against the Jews and against Marcion, no doubt assuming different roles for each work.