Research

Some of my published research is in the history of philosophy—specifically, the history of the Liar Paradox in the Islamic World. The rest of it is in contemporary philosophy, with a focus on puzzles about nonexistence, both in the context of time and in the context of fiction.

History of Philosophy

• Ahmed Alwishah and David Sanson. Forthcoming. “The Liar Paradox in the Islamic World.” In Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta and Uri Nodelman. DRAFT

  This article covers the treatment of the Liar Paradox within the Arabic tradition from the 10th century to the 15th century. In the earliest texts, the Liar occurs either as a theological counterexample or as a logical sophisim. During the 13th century, it became a standard example discussed by logicians, and several distinct solutions were articulated and defended. And at the end of the 15th century, the Liar had its philosophical moment, as it became the subject of an extended debate between two rivals, Sadr al-Din al-Dashtakī (d. 1498) and Jalāl al-Din al-Dawānī (d. 1502), who each wrote free-standing treatises on the topic.

• Ahmed Alwishah and David Sanson. 2026. The Final Word: Al-Dawānī and the Liar Paradox in the Islamic World. Oxford, New York: Oxford University Press.

  This book offers the first comprehensive study of the Liar Paradox in the Islamic philosophical tradition, up to the fifteenth century. It traces the role the Liar played in debates in logic, philosophy of language, and theological ethics, and includes the first complete English translation of al-Dawānī’s treatise, The Final Word in Solving the Paradox of the Irrational Root.

• David Sanson and Ahmed Alwishah. 2017. “Al-Taftāzānī on the Liar Paradox.” Oxford Studies in Medieval Philosophy 4: 100–124. https://doi.org/10.1093/acprof:oso/9780198786368.003.0005.

  Al-Taftāzānī (1322–1390) was a Persian polymath who wrote on a wide range of subjects—grammar, logic, theology (kalām), jurisprudence (fiqh), and literature. Here we translate and discuss his remarks on the Liar Paradox, in which he (a) presents the first example of a “Liar Cycle” or “Deferred Liar” in the tradition, (b) gives the paradox a puzzling name—the fallacy of the “irrational root” (al-jadhr al-aṣamm)—which became the standard name for the paradox in the tradition, and (c) suggests a connection between the paradox and what it tells us about the nature of truth and falsehood, and related puzzles concerning reason and the nature of goodness and badness.

• Ahmed Alwishah and David Sanson. 2009. “The Early Arabic Liar: The Liar Paradox in the Islamic World from the Mid-Ninth to the Mid-Thirteenth Centuries CE.” Vivarium 47 (1): 97–127. https://doi.org/10.1163/156853408X345909a.

  We describe the earliest occurrences of the Liar Paradox in the Arabic tradition. The early Mutakallimūn claim the Liar Sentence is both true and false; they also associate the Liar with problems concerning plural subjects, which is somewhat puzzling. Al-Abharī (1200-1265) ascribes an unsatisfiable truth condition to the Liar Sentence—as he puts it, its being true is the conjunction of its being true and false—and so concludes that the sentence is not true. Al-Tūsī (1201-1274) argues that self-referential sentences, like the Liar, are not truth-apt, and defends this claim by appealing to a correspondence theory of truth. Translations of the texts are provided as an appendix.

Contemporary Philosophy

• David Sanson and Ben Caplan, and Cathleen Muller. 2017. “Counting Again.” Grazer Philosophische Studien 94 (1–2): 69–82. https://doi.org/10.1163/18756735-000017.

  We consider a recurring objection to fictional realism, the view that (broadly speaking) fictional characters are objects. The authors call this the counting objection. Russell presses a version of the objection against Meinong’s view. Everett presses a version of the objection against contemporary fictional realist views, as (in effect) do Nolan and Sandgren. As the authors see it, the objection assumes that the fictional realist must provide criteria of identity for fictional characters, so its force depends on the plausibility of that assumption. Rather than coming up with such criteria, a fictional realist might argue that the demand is misplaced.

• David Sanson. 2016. “Worlds Enough For Junk.” Res Philosophica, January. https://doi.org/10.11612/resphil.2016.93.1.1. PDF

  A cap is something that is not a proper part. A junky thing is something that is not part of any cap. Can there be junky things? The view that possible worlds are concrete cosmoi suggests not: every possibility involves the existence of a cosmos, and that cosmos is a cap. But this can be overcome by allowing that some parts of a cosmos may collectively represent a complete possibility. The resulting view helps cast light on some important features of the Modal Realist’s attitude toward modality.

• David Sanson. 2016. “Frivolous Fictions.” Res Philosophica 93 (2): 357–76. https://doi.org/10.11612/resphil.2016.93.2.8. PDF

  We want to say both that Sherlock Holmes does not exist, and that he is a fictional character. But how can we say these things without committing ourselves to the existence of Sherlock Holmes? Here I develop and defend a noncommital paraphrase of quantification over fictional characters, modeled on the noncommital paraphrase Kit Fine provides for quantification over possibilia. I also develop and defend the view that names for fictional characters are weakly non-referring, in Nathan Salmon’s sense, and so provide us with a noncommital means to express singular propositions. The resulting position allows us to reap the benefits of Fictional Realism without paying the associated ontological cost.

• Ben Caplan and David Sanson. 2011. “Presentism and Truthmaking.” Philosophy Compass 6 (3): 196–208. https://doi.org/10.1111/j.1747-9991.2010.00380.x.

  Presentism, according to which reality is limited to the present, is a natural view, but it is incompatible with the claims that reality invariably has a say in which propositions are true and that not all truths about the past are made true by the present. We survey some responses to this incompatibility.

• David Sanson and Ben Caplan. 2010. “The Way Things Were.” Philosophy and Phenomenological Research 81 (1): 24–39. https://doi.org/10.1111/j.1933-1592.2010.00357.x.

  Presentists say that only the present is real.1 Saying that might seem like a pretty good way of accounting for what is special about the present, but it might also seem like a pretty bad way of accounting for anything about the past. The literature suggests a fairly straightforward solution: facts about how things once were, it turns out, just are special facts about how things are now (for example, facts about the present instantiation of primitive “tensed” properties). In this paper, we argue that solutions of this sort are wrong.