My research focuses on the way that ancient Pyrrhonian skeptics understood scientific inquiry in light of their skeptical philosophy. Sextus Empiricus begins his Outlines of Pyrrhonism (PH) with the claim that skeptics are perpetual inquirers. They are not satisfied with the answers that have been offered, nor do they claim - as many modern skeptics do - that answers cannot be given; instead, they keep looking (PH I 1-3). But Sextus also says that the skeptic suspends judgment, especially in matters philosophical or theoretical (PH I 8, 13). How can real inquiry continue when the skeptic withholds assent from all philosophical claims? Doesn't the very notion of inquiry require assent to certain standards, namely about what would count as adequate grounds to establish some claim?

To address these issues and themes, I am working on a monograph entitled Inquiry and Expertise in Ancient Skepticism, which is an expansion of my dissertation. My dissertation answers the question “What is skeptical science?” Sextus claims skeptics accept the teaching of certain forms of technical expertise (technai). Given that he himself was a physician and that he claims to accept certain empirically based forms of expertise, including astronomy, we should conclude that Sextus thinks skeptics can be scientists. How can this position be consistent with his claim that skeptics live without belief? Even if the skeptic can consistently engage in scientific inquiry, it is not at all clear what sort of science this would be.

I answer this question by examining Sextus' treatise Against the Professors (M I-VI), a little studied text that criticizes the putative experts of six technical disciplines: grammar, rhetoric, geometry, arithmetic, astrology, and music theory. My general approach involves an analysis of Sextus’ critique, which I argue implies the boundaries and structure of a discipline that the skeptics could consistently accept as legitimate. Given what Sextus says about these domains, a legitimate skeptical science must be a non-axiomatic empirical inquiry that establishes a collection of “signs” gathered through repeated observations of correlated events. These so-called signs are not meant to explain any natural phenomena; rather, they predict future occurrences for some practical purpose. While the notion of a non-explanatory science may seem like an oxymoron to some, Sextus clearly foreshadows Duhem (1954) who claims that physical theory does not aim to explain the nature of reality. Skeptical science is instead meant to be useful for the skeptical way of life

The monograph involves not just a revision of the dissertation but also new studies on the skeptical critique of rhetoric, and on skeptical research and inquiry. I presented a version of the chapter on rhetoric at the joint Universidad Nacional Autonoma de Mexico (UNAM) / UT Austin Philosophy Conference in Mexico City in 2017, and I am currently working on the latter chapter. Ultimately, the resulting work will not only be the first book length treatise on Against the Professors in English, it will also provide an original contribution to our understanding of Pyrrhonian skepticism and its role in the development of science.

In addition to the monograph, I am working on a series of papers which explore the skeptic’s argumentative strategies as they relate to skeptical inquiry and the goal of suspending judgment. The first of these papers, published in Apeiron, presents a new problem for the standard interpretation of the five Modes of Agrippa. The Modes are typically thought to be argument forms or objections to dogmatic arguments, but I claim that such an interpretation cannot make sense of the skeptics using the Modes to suspend judgment themselves. In response to this (and other problems), I argue that the Modes are types of dialectical challenge that skeptics can use in an endless inquiry into any dogmatic position.

The second paper in this series examines the role that disagreement plays in generating the skeptic’s suspension of judgment (epochē). This paper, which is currently forthcoming in Archiv für Geschichte der Philosophie argues that skeptical suspension of judgment comes about, not through the precarious balance of argumentative forces, but as a result of following a particular norm that demands epochē in the face of philosophical disagreement. Once we see that the skeptics follow this norm, it not only helps make sense of a number of puzzling passages in Sextus’ Outlines, but it also answers the problem some scholars have raised, namely how can the skeptics continue investigating once they have suspended judgment? I show how such investigative activity is coherent.

My interpretation of skeptical suspension in the face of disagreement raises another puzzle, namely why does Sextus talk about philosophical oppositions having “equal weight” (isostheneia) if the persuasiveness of the arguments on either side of the question does not generate the epochē as so many scholars have claimed. This is the topic for my third paper of the series, which I have presented already at a couple of conferences.

In addition to my research into Pyrrhonism, I study other figures in the history of skepticism as well as the development of ancient scientific theories. I currently have a paper under review that looks at the Epicurean doctrine of the swerve, that notorious assertion that atoms randomly change their trajectory slightly as they move. I examine an argument that Lucretius offers for the swerve. He claims that the swerve is needed to explain why any macroscopic objects exist. If there were no swerve, there would be no collisions because all of the atoms would fall like raindrops (De Rerum Natura II 217-225). While this argument is typically dismissed by scholars, I claim that without the swerve, the "atomic rain" was indeed implied by Epicurean physics, which means that Epicurus needed some principle like to swerve to explain the existence of our kosmos.

I am also currently working on a paper about the ethical thought in Xenophanes of Colophon. Xenophanes is most well known for his epistemological fragments, which seem to express a form of skepticism, and for his theological fragments, which are critical of mythic stories that portray the gods from the perspective of a shameful anthropomorphic provincialism. What I think scholars have missed is the ethical content of Xenophanes’ thought. I argue that the Colophonian was an ethical philosopher in the mold of Socrates: He critically confronts the social and moral norms of his community in order to spur them to seek wisdom by inquiring into virtue and appropriate action.

Finally, looking forward, I plan to explore the way that ancient thinkers understood failures in explanation: Are all failures of explanation simply mistakes, or are some aspects of reality inexplicable? We are all familiar with Thrasymachus' radical claim in the first Book of the Republic, that the true expert never errs. Plato suggests in several places that a genuine science or technē is able to explain and predict every phenomenon within a given domain. Aristotle seems to have been drawn to this view insofar as he begins the Posterior Analytics saying that scientific understanding is of explanations that are necessarily true. But later, in the same treatise, Aristotle admits that we can also understand things that happen “for the most part,” suggesting that scientific understanding of the sublunary world may have explanatory “gaps.” That is, some phenomena, although generally predictable, do not happen always in the same way, and we, as scientists, can understand and explain these occurrences, even though any particular occurrence may admit of exception.

I plan to continue exploring the ancient response to such “gaps” in explanation. The accommodation of error and uncertainty in ancient science eventually leads to the development of the idea of a 'conjectural art' (stochastikē technē) during the Roman period as evidenced by disputes among doctors and philosophers like Galen and Alexander of Aphrodisias. But we can see already in the early Hippocratic writers the struggle to define and delineate what counts as expertise in the area of medicine in light of failures on the part of doctors. Aristotle clearly wants to retain the high standard of knowledge in the sciences that Plato advocates, yet the Stagirite recognizes that there are irregularities or exceptions science cannot explain. Following Aristotle, the notion of a conjectural art becomes an important part of the response to critiques of expertise and science, first developed by the skeptical Academy to attack Stoic epistemology, and later expanded by the Pyrrhonists.