Suppose you know X. How do you know? Maybe you know because of Y. How do you know Y? Maybe the answer is Z. How do you know Z?
This is the regress problem of knowledge, also called the Agrippan trilemma and the Münchhausen trilemma. It is based on the supposition that if we claim to know something, we must have a reason for it and that reason must itself be something that we know. This leaves open four possible solutions. One is skepticism, the belief that we have no knowledge. The most common is foundationalism, which posits certain basic facts that require no external reasons to be justified. Another option is coherentism, which solves the problem via a kind of circular reasoning or justification loop. And finally, there is infinitism, the view that there is no end to the regress. For any chain of justification, the final member of the chain will always be unjustified, and it is always possible to go looking for further reasons of reasons of reasons. As infinitist Peter Klein puts it, knowledge is never “settled”. Even so, says Klein, it is still possible to have knowledge. In this interview, Klein first argues why he thinks coherentism, foundationalism, and a certain kind ofskepticism all fail. He then explains his own account of justification, as “something that we do”, and how it makes the infinitist picture look more plausible than it first seems.…
In this second part of my case against 100% certainty, I tackle claims to logical certainty. These include appeals to the three fundamental laws of logic: the Law of Excluded Middle, the Law of Non-Contradiction, and the Law of Identity. To call excluded middle into doubt, I discuss non-referring terms, vagueness, fuzzy logic, and Aristotle’s problem of future contingents. For contradiction, the topics are legal contradictions, the Liar paradox, and Zeno’s Arrow. To argue against certainty of the law of identity, I cover Theseus’s ship, problems with time, problems of mereology, and the universe of symmetrical spheres. I then argue that even claims like “2+2=4” and “bachelors are bachelors” can’t be fully foolproof. Finally, a quick barrage of skeptical concerns – concerns that, while they may not be enough to justify a self-defeating view like skepticism, are enough to block claims to 100% certainty.
0:20 – Quick pt. 1 recap
1:21 – Introducing claims to logical certainty
2:21 – Classical logic, syllogistic logic, and the 3 laws
5:48 – Law of Excluded Middle
6:45 – Non-referring terms: the present king of France
9:16 – Vagueness and fuzzy logic
12:11 – Future contingents
13:51 – Law of Non-Contradiction – DeMorgan’s Law
15:38 – The legal case
18:22 – Liar paradox
22:09 – Zeno’s arrow
26:45 – Law of Identity – Theseus’s ship
29:26 – Content of an instant
31:17 – Mereological – Tibbles
36:06 – Symmetrical spheres
37:47 – Do we understand identity?
In this interview with epistemologist Jim Slagle, we discuss the Epistemological Skyhook. That is, the argument that certain philosophical positions (such as naturalism and determinism) give us a reason to believe in skepticism, which in turn, gives us a reason to doubt the reasoning that got us to the position in the first place. If the argument is correct, then while it is possible that naturalism or determinism might be true, it is impossible for us to believe in them. In this first part of our two-part discussion, we focus on Alvin Plantinga’s version of the argument.