skepticism; and whether skepticism can be captured in such a simple formula.
Maybe skepticism is only a construction of its opponents who want to refute it in order to get a sense of security by refuting it.
On closer inspection, we see that both this skepticism and the refutation of it presuppose a very specific concept of truth; that this concept is not at all the original one; and therefore that this refutation is [22] not a radical consideration at all but only the semblance of a selfevident presupposition, only the mirage of a limit.
To be sure, the question “What is truth?” is the basic question—not, however, because it maintains that the problem of skepticism is already solved from the beginning. Rather, the problem of skepticism belongs in an essential way among the set of questions about the condition of the possibility of truth at all. But then there is a multitude of things to be discussed.15
* * *
1. One needs to demonstrate that this supposedly fundamental consideration—the refutation of skepticism—still does not and cannot deal with the real, genuine presuppositions. That is because both sides—the skeptic and his refuter—presume that the truth, whose being and non-being they are debating, is propositional truth. This is especially clear in the one who would refute skepticism. To confound the skeptic, he appeals to the principle of non-contradiction: there can be no truth where there is contradiction, especially the self-contradiction we find in the assertion of skepticism. But contradiction and noncontradiction make sense as a criterion only where this criterion is applied to “diction,” to speaking back and forth, i.e., to λόγoς, a statement in the sense of a proposition. Ultimately, the refutation is centered on the thesis that in every true statement, so one says, the existence of truth is co-affirmed. There the refutation rests its case.
It doesn’t even go so far as at least to show why (i.e., on what basis) it must be the case that the existence of truth is co-affirmed in every true statement. It presumes the matter is self-evident. It never asks, much less answers, that question, and therefore this supposedly fundamental consideration that wants to get to ultimate presuppositions is not fundamental at all. [23]
2. This supposedly fundamental consideration makes an appeal to the principle of contradiction as a criterion, and therefore an appeal to fundamental proof and provability. But what does proof mean? What is the origin of the claim to prove? What is the condition of the possibility of proof at all? What is the origin of the “why?”—not to mention
15. [Here Heidegger ends his lecture of 9 November 1925.]