Note: As a service to fellow researchers, I am going to post summaries of the works of the church fathers I examined in my book The Trinitarian Testimony of the Spirit. These sections were included in my original dissertation but were cut from the published version. Original footnotes are included as endnotes below; in conjunction with the essential bibliographies and critical biographies I have posted, this should help those looking to get into the literature on the early church fathers. I have been struck by how many published sources read the primary sources with a fairly uncritical lens; in these summaries, like any good historian, refuse to take primary sources at face value.
The Works of Justin Martyr
Eusebius lists eight works he ascribes to Justin: two apologies, five additional (non-extant) treatises, and the Dialogue with Trypho. The first apology listed by Eusebius is almost certainly what we know as 1 Apology, the earliest of Justin’s extant writings. This apologetic writing, as Eusebius notes, is directed to the emperor Antoninus Pius and the philosophers Verissimus and Lucius. This defense of the Christian faith, most likely intended for a non-Christian Roman audience, appeals for justice, refutes spurious charges by Christianity’s opponents, and presents the basics of the Christian faith.
The short document that scholars refer to as 2 Apology presents more of a problem, as the second apology listed by Eusebius was said to be addressed to Antoninus Verus (that is, Marcus Aurelius, 161–180 CE), which does not match what we know of 2 Apol., a document neither addressed to this emperor nor even a complete, independent work in its own right. As such, most scholars have argued that 2 Apol. is in fact an appendix to its lengthier predecessor. More recently, however, Denis Minns and Paul Parvis have claimed that 2 Apol. is in fact a collection of unrelated fragments, thus envisioning Justin as a writer who “kept tinkering with his original apology, adapting it and perhaps expanding it” even while keeping notes for quick reference during his public debates. In any event, the major concerns of this document are to respond to recent injustices that had occurred in Rome under the prefect Urbicus and to the claims of the aforementioned Crescens. In light of the internal evidence of these texts, most scholars date both Apologies to the years 151–155 CE.
Justin’s only other authentic, extant work is his Dialogue with Trypho. This lengthy writing purports to record a debate lasting two days between Justin and a Jew named Trypho in which Justin seeks to convince Trypho that Christianity is the true philosophy and that Jesus is the fulfillment of Old Testament prophecy. While the text suggests that this debate happened shortly after the end of the Bar Kochba revolt (ca. 135 CE), most scholars, on account of Dial.’s quotations from 1 Apol., date Dial. after 1 Apol. to ca. 160 CE, while Justin was in Rome. The work is addressed to a Marcus Pompey, though the most common modern scholarly position is that this work was written to a group of Gentiles considering becoming Jewish proselytes. Another strand of scholarship has argued, however, that Dial. was also intended for a combined Jewish and Christian audience in light of purported missionary activity between the two communities during this time. However, we must bear in mind that at this time Judaism and Christianity in many places existed side-by-side, with the boundaries between the two not always sharply defined. As Daniel Boyarin has plausibly insisted, the more sharply defined borders that emerged as early as the late first century were “constructed and imposed” in a complex process of mutual self-definition that transformed somewhat socially differentiated groups into what we now think of as distinct religious communities. As such, it is likely that the best lens by which to read Dial. is one in which Justin is actively engaged in publicly constructing a Christian identity that is distinct from that of the Judaism that he believes to be a threat and competitor to his adopted faith.
Complicating all scholarly study of Justin is the fact that his writings are preserved (alongside other writings falsely attributed to Justin at a later time) in a single manuscript, Paris 450, which dates to September 11, 1363. Not only does this manuscript show evidence of a corrupt text, but there are several major lacunae of uncertain length. The standard critical edition of 1–2 Apol. is that of Charles Munier (2006), while the standard critical edition of Dial. is that of Miroslav Marcovich (1997).
 Hist. eccl. 4.18 (SC 31:195–97).
 Cf. 1 Apol. 1.1 (SC 507:126); see Minns and Parvis, Justin, 34–41, on the formal addressees of this work.
 Barnard, Justin Martyr, 14–17. Minns and Parvis (Justin, 44) take Justin’s primary purpose for writing to be petitioning for relief from unjust Roman persecution of Christians, but note that 1 Apol. could also be useful for winning and instructing new converts (Justin, 46). See Minns and Parvis, Justin, 46–54, for an extensive plan of 1 Apol.
 So, e.g., Chadwick, “Justin’s Defence,” 277–78; Osborn (Justin Martyr, 11) sees 2 Apol. as an appendix to the first edition of 1 Apol.; Barnard (Justin Martyr, 18) also sees 2 Apol. as a supplement to 1 Apol. that was “called into existence by a specific injustice.” So also Rokéah, Justin Martyr and the Jews, 2; Allert, Revelation, 32 n. 143; Miroslav Marcovich, Iustini Martyris Apologiae pro Christianis, PTS 38 (Berlin: De Gruyter, 1994), 8–11. On the history of scholarship concerning the problem of 2 Apol., see Minns and Parvis, Justin, 21–24.
 Minns and Parvis, Justin, 27–28. They also suggest that, for codicological reasons, 2 Apol. 14–15 (SC 507:364–68) should in fact be placed at the end of 1 Apol. (Justin, 28–31). On the issue of how to classify 2 Apol., see further Paul Parvis, “Justin, Philosopher and Martyr: The Posthumous Creation of the Second Apology,” in Justin Martyr and His Worlds, ed. Sara Parvis and Paul Foster (Minneapolis: Fortress, 2007), 22–37.
 Minns and Parvis, Justin, 54–56.
 Barnard, Justin Martyr, 19; Allert, Revelation, 34; Osborn, Justin Martyr, 8; Marcovich, Apologiae pro Christianis, 8–11. Minns and Parvis (Justin, 44) more narrowly specify that they were written in 153 or 154 CE. Rokéah (Justin Martyr and the Jews, 2) dates them later, in 155 CE.
 The extent to which Dial. reflects an actual conversation between Justin and Trypho is an open question, though I agree with Barnard’s solution (Justin Martyr, 23–24), which finds some historical basis in an actual debate with Trypho ca. 132–135 CE that Justin subsequently expanded and reworked ca. 160. This in turn raises the question of the identity of the “historical Trypho,” of whom we can say little with confidence apart from that he is almost certainly not to be identified with Justin’s contemporary Rabbi Tarphon; cf. Barnard, Justin Martyr, 24; Osborn, Justin Martyr, 12–13; Demetrius C. Trakatellis, “Justin Martyr’s Trypho,” HTR 79 (1986): 289–97. On Trypho’s Judaism, see Allert, Revelation, 84–87. Going a step beyond what most scholars seem prepared to accept, Timothy J. Horner posits the existence of a so-called “Trypho Text,” from which we can deduce the character of Trypho and relate him to second-century Judaism in Asia Minor; see Timothy J. Horner, “Listening to Trypho”: Justin Martyr’s Dialogue Reconsidered, CBET 28 (Leuven: Peeters, 2001).
 Dial. 1.3 (PTS 47:70).
 So Barnard, Justin Martyr, 23; Rokéah, Justin Martyr, 2. Osborn (Justin Martyr 8) proposes 155–160 CE; Allert (Revelation, 34) thinks any date betweeen 155–167 CE is equally plausible.
 Dial. 141.5 (PTS 47:313); cf. Dial. 8.3 (PTS 47:85).
 See, e.g., Jon Nilson, “To Whom is Justin’s Dialogue with Trypho Addressed?” TS 38 (1977): 538–46; Miroslav Marcovich, Iustini Martyris Dialogus cum Tryphone, PTS 47; Berlin: De Gruyter, 1997), 64–65; Oskar Skarsaune, The Proof from Prophecy: A Study in Justin Martyr’s Proof-Text Tradition—Text-Type, Provenance, Theological Profile, NovTSup56 (Leiden: Brill, 1987), 258–59. Older scholarship tended to maintain that Dial. was written to Gentile Christians; cf. Chadwick, “Justin’s Defence,” 278; Barnard, Justin Martyr, 24 n. 1.
 See, e.g., Theodore Stylianopoulos, Justin Martyr and the Mosaic Law, SBLDS 20 (Missoula, MT: Scholars Press, 1972), 10–20, 169–95; Allert, Revelation, 37–61; Rokéah, Justin Martyr, 6–11. For still another view of the audience of Dial., see Charles H. Cosgrove, “Justin Martyr and the Emerging New Testament Canon: Observations on the Purpose and Destination of the Dialogue with Trypho,” VC 36 (1982): 209–32, esp. 217–18, who argues for an exclusively Christian destination.
 Daniel Boyarin, Border Lines: The Partition of Judaeo-Christianity, Divinations (Philadelphia: University of Pennsylvania Press, 2004), 1–2. This view is thus distinct from the traditional notion of the “parting of the ways,” which presupposes the preexistence of these two discrete religious entities.
 This is not to say that Justin did not have multiple audiences in mind as he composed Dial., which I believe to be almost certain. Still, Boyarin and other recent works on early Christianity have rightly stressed the need to take this process of self-definition seriously, as opposed to simply accepting that the way that Justin and other apologists presented the world was an accurate representation of reality.
 Goodenough (Theology of Justin Martyr, 80), notes the existence of some checks on Paris 450 in the form of later quotations and an independent fragment of 1 Apol. 65–67 contained in Codex Ottobonianus Graecus 274, which dates to the fifteenth century. Concerning the physical characteristics of this manuscript and an argument for its original provenance (Mistra or Constantinople), see Minns and Parvis, Justin, 3–5. There is also one complete manuscript of the Apologies, Codex Phillipicus 3081, but this is widely recognized to be an apograph of Paris 450 (Minns and Parvis, Justin, 6).
 According to Minns and Parvis (Justin, 19–21), the scribe of Paris 450 was himself using a damaged manuscript and thus often had to resort to contextual guesswork to fill in the gaps. Cf. Osborn, Justin Martyr, 12.
 Perhaps the most notorious are the presumably very lengthy lacunae after Dial. 74.3 (PTS 47:198) and in 2 Apol. 2 (SC 507:326). Allert (Revelation, 34) suggests that the introductory dedication that would have preceded Dial. has been lost. On the ancestor of Paris 415 as a “leaf-shedding manuscript,” see again Minns and Parvis, Justin, 28–31. On the transmission of Justin’s writings, see further Marcovich, Dialogus cum Tryphone, 1–7; idem, Apologiae pro Christianis, 1–8.
 Charles Munier, Justin: Apologie pour les chrétiens, SC 507 (Paris: Cerf, 2006). The paucity of manuscripts of Justin’s writings means that critical editions are very consistent from one to another.