Thank you for the thorough response. I haven't been able to find David Kelley's book, so maybe this is premature, but I had some concerns about the Stolen Concept Fallacy (SCF) described above and in the materials you suggested (1) Brendan, in his lecture series, describes SCF as it applies to a special case. Specifically, he describes SCF as it applies to the skeptic’s attempt to discredit the validity of the senses by demonstrating their inconsistency. The senses are inconsistent because different senses yield evidence for different conclusions about the same object or because the same sense yields evidence for different conclusions at different times. Brendan argues that the skeptic’s reliance on the senses to demonstrate their inconsistency commits the skeptic to the proposition that the senses are or can be accurate. However, this doesn’t adequately describe how the skeptic’s argument functions in the special case. The skeptic’s argument is parasitic on the empiricist’s beliefs that the senses are accurate, and that the senses are accurate only if they are consistent; but the skeptic’s attempt to demonstrate that the senses are inconsistent doesn’t obviously commit her to the truth of these beliefs. The skeptic could, for example, have no commitment to the senses accuracy. This would not affect the effectiveness of her argument, which relies on the empiricist’s and not her own belief that the senses are accurate. (2) Brandon addresses SCF more generally in his article. He compares the claims that reality is an illusion and that we cannot distinguish reality from illusion to Proudhon’s claim that “all property is theft.” There are at least two possible translations of Proudhon’s claim. (a) There is no state of affairs in which property is not theft. (b)There may be some states of affairs in which at least some property is not theft, but the current state of affairs is not within this set. Brandon correctly translates Proudhon’s claim as (a), and argues that the claim is self-defeating since the concept of theft “logically and genetically depends on the antecedent concept of ‘rightfully owned property’… If no property is rightfully owned, that is, if nothing is property, there can be no such concept as ‘theft.’” However, the claim that we cannot distinguish reality from illusion often more closely resembles (b). Unlike the claim that reality is illusion, the claim that we cannot distinguish reality from illusion doesn’t obviously lead to the sort of self-contradiction that Brandon argues Proudhon’s claim does. The skeptic doesn’t claim that knowledge is, by definition, not-knowledge, but rather that our beliefs do not currently satisfy the requirements of knowledge whatever they may be. This claim doesn’t deny the theoretical possibility of our having knowledge in all cases. (3) Brandon’s and Peikoff’s explanations of SCF create asymmetries between what I can legitimately claim about myself in one case and what I can legitimately claim about myself in all cases and what I can legitimately claim about myself and what I can legitimately claim about others. Consider the following statements: (a) John cannot distinguish illusion from reality in this case (b) John cannot distinguish illusion from reality in all cases (a') I cannot distinguish illusion from reality in this case (b') I cannot distinguish illusion from reality in all cases SCF permits me to conclude (a), (b), and (a'), but forbids that I conclude (b'), since I cannot disavow the validity of my own senses in all cases. Similarly, it permits John conclude (a), (a'), and (b'), but not (b). This is bizarre.