Question: **Agrippa's 5 tropes**

1. *Dissent*: For every thesis an anithesis
2. *Relation*: Point of view matters.
3. *Infinite Regress*: Justifications need justifications need justifications ... *ad infinitum*
4. *Axioms*: Assume something to be true *sans* justification.
5. *Circularity*: The conclusion appears in the premises.

3, 4, 5 (above), together, constitute the well-known *Agrippa's trilemma*.

One *seemingly* strong argument against skepticism has been to point out that it's a *peritrope* (self-refuting). However, for it to be so, it *must be a sound argument* and if that's the case the argument that skepticism is a peritrope is itself a peritrope and this further argument I just made is also one ... *ad infinitum*. Skepticism is unsound only if skepticism is sound.

We end in a rather mind-boggling contradiction

1. For skeptics, skepticism is a good argument implies it's a *peritrope*.
2. For dogmatists, skepticism is a *peritrope* implies it's a good argument.

Skepticism → Peritrope → Skepticism → ... ad infinitum/ad nauseum

How do we extricate ourselves from this quagmire?

Answer: 
The history of philosophy has many examples of people who think they have refuted scepticism - Descartes, Berkeley, Locke and Hume not to mention Russell, Ryle and Wittgenstein are all examples. And yet people keep returning to the issue.

One would be justified in thinking that the problem is to understand why this is so.

For example, in the case of Agrippa's argument, I see it as an effective objection to foundationalist views about knowledge, but not against knowledge as such. It is possible that other arguments do not have the radical conclusions claimed for them and they are actually aimed at different forms of scepticism. Some, as in the case of Agrippa's argument, may be right.

Another line of thought can be seen in Hume and Russell and Ayer. Scepticism is not *per se* an enemy to be overcome, but a friend and ally to be relied on. We need to chart a distinction between destructive scepticism and constructive scepticism. That would, at least, be a clearly different problem.

Stanley Cavell in his *Claim of Reason* and *In Quest of the Ordinary* argues that we need to understand, rather than refute, scepticism (he means radical or destructive scepticism). He sees it as an inescapable part of the human condition. His project goes beyond the boundaries of analytic philosophy, but I can't see that as a fatal objection.
As of the titular question: No, it is not.

Tim Button has formally shown in his book *The Limits of Realism* that **all famous historical arguments for skepticism are incoherent/self-contradictory**.

For what it's worth, he does show the same for all famous historical arguments for realism, hence the title of the book.