Project Director

Ribeiro, Brian

Department Examiner

Plaisted, Dennis; Mills, Ethan


Dept. of Philosophy and Religion


University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)


The self-refutation problem is an all too familiar objection to all varieties of skeptical arguments, in fact, it is as old as skepticism itself. My analyses will first focus on the arguments and objections to ancient Pyrrhonian skepticism. The Stanford Encyclopedia of Philosophy describes the goal of Pyrrhonian skepticism as “suspension of judgment as a way of achieving calm (ataraxia) in the face of seemingly intractable disagreement.” The position involves a series of arguments, or, “modes”, for evaluating claims in such a way that the evidence for and against accepting a claim are equally balanced, leaving the inquirer with no rationally acceptable choice but to suspend judgment. Sextus recorded and responded to two separate counts of self-refutation. The first objection claims that the skeptical phrases such as, “It is no more this than that,” are self-undermining and the second is that Sextus’ skeptical argument against proof is self-undermining. My thesis will focus on these two objections as correlated but theoretically distinct problems. I will first focus on Luca Castagnoli’s responses to Mark L. McPherran’s arguments in defense of the skeptical position in regard to these two objections to highlight the nature of the issue. McPherran defends the claim that Sextus openly endorses the self-refutation objection to the argument against proof since it serves the purpose of achieving the Pyrrhonian goal of suspending judgment. Castagnoli argues, contra McPherran, that Sextus is not embracing self-refutation but formulates two arguments that attempt to show that the self-refutation objection fails to overthrow the intended skeptical ends of suspension of judgment. In the case of the skeptical phrases, Castagnoli asserts that even if one tried to utter them dogmatically, that is, as an assertion, they couldn’t do so, because they have a logical immunity to dogmatism, resulting in suspension of judgment. In the case of the argument against proof, Castagnoli claims that the argument against proof succeeds in drawing proof into its refutational scope, and thus requires one to suspend judgment about the status of proof as a successful operation. Central to Castagnoli’s claim is that McPherran has misapplied the concept of “self-refutation” to Sextus’ Greek text, asserting that Sextus never attached any truth to his claims, and thus, never admitted their capacity to become falsified by themselves. Instead, Castagnoli uses philological and linguistic interpretation to mount the argument that the phrases and argument against proof are non-assertive, only becoming “self-bracketing” when misunderstood as an assertion by a dogmatist. In section 2.1 I will concur with Castagnoli’s conclusion that Sextus intended the phrases to be expressed without assertion, but not because they are logically immune to dogmatism. I will first demonstrate how the argument from logical immunity fails in the case of the phrases and then show that Sextus’ text expressly discourages and defies such formulations because their nature as self-reported expressions of pathos is incompatible with logical formulation. Next, in section 2.2 I will challenge Castagnoli’s non-assertive “self-bracketing” interpretation of the argument against proof on the grounds that a mild, non-committal approach to the argument is explicitly and theoretically inconsistent with Sextus’ strong language regarding the capacity for the argument to “destroy” itself. Section 3 will support this reading by illustrating the direct conceptual correlation between logical truth and metaphysical existence in Sextus’ examinations and introduce the two realms of existent things – physical and mental existence. Section 4 will introduce and examine foundational research in the cognitive sciences that provides insightful conclusions about the mental reality of the reasoning process. Section 5 will introduce and situate a concept of my own, intellectual sentiments, as a development on the research explored in section 4. Section 6 will place the AAP back into frame situated in the context of the cognitive understandings developed in section 5, and advocate for a reading of Sextus that uses this cognitive context to defeat the self-refutation objection. I will return to the present day in my concluding remarks to discuss the consequences that intellectual sentiments, and other conclusions revealed throughout the course of the paper, may have for the reasoning process as an extension of neo-skeptical investigations into the incompatibility of phenomena hailing from contemporary cognitive sciences with pure rational thought in the modern age.


I am deeply indebted to Dr. Joshua Davies of the University of Tennessee at Chattanooga’s Modern and Classical Languages Department for providing me with linguistic expertise, as well as, database and dictionary resources during several crucial points of my research into Sextus Empiricus’ original Greek text. I am also very grateful to Dr. Ethan Mills and Dr. Dennis Plaisted of UTC’s Philosophy and Religion Department for the insightful analyses, suggestions, and criticisms they offered after reviewing this paper in their capacity as members of my departmental honors thesis examination committee. And of course, this project would not exist without the support and expertise of my thesis director, Dr. Brian Ribeiro, whose guidance helped me to maintain focus and challenged me to seek novel approaches to the problems taken up in this paper. I am grateful for his willingness to support this endeavor and to shepherd my ideas from inception to completion.


B. A.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Arts.




Evidence--Philosophy; Logos (Philosophy); Philosophy and cognitive science; Philosophy of mind; Skeptics (Greek philosophy)


Sextus, Empiricus


Pyrrhonism; Skepticism; proof; Sextus Empiricus; Cognitive Science; Philosophy of Mind


Philosophy of Mind

Document Type



iv, 98 leaves