Peirce and Wittgenstein on Common Sense

I intend to start from Peirce’s idea that precision and certainty have different meanings: “it is easy to be certain – he writes – one has only to be sufficiently vague” (CP 4.237). Certainty is not a result of inquiry, but a premises of it, and so it is connected with vagueness and uncertainty. Its value doesn’t belong to the order of argumentative discourse, but of pragmatic habits. Wittgenstein in On certainty reaches a similar conclusion. Both Peirce and Wittgenstein resolve, thus, a typical Cartesian theme, that of certainty, in a totally anticartesian sense. At the same time, they seem to recuperate some Cartesian topics. Indubitable evidence, lume naturale, instinctive insight and primary knowledge are common notions to both the authors that, nonetheless, maintain the totally antiintuitionistic, antidualist and antimentalistic account from which their philosophies rose. I will analyze some propositions from On certainty by Wittgenstein and will show how close are they to some of the leading propositions of Peirce’s ’68 writings. We begin with all our prejudices, writes Peirce, that “does not occur to us can be questioned” (W2:212); the “play of doubting already presupposes certainty”, goes on Wittgenstein (C 115). Our common sense guides us through practice, leading us to be sure of many things, without a real justification. So there is a certainty which we comply with, that goes beyond truth and falsity, that is not a way of seeing, but a way of acting, as Wittgenstein says. And, as any pragmatic habit, it is immediate and in some sense final (remember that habit is the Final Logical Interpretant). Yet, as far as we try to explain the reasons of our beliefs, our certainty becomes vague, and so uncertain, and the play of infinite semiosis begins.