Genuine belief and genuine doubt in Peirce

Peirce makes it clear that doubt and belief oppose one another. But that slogan admits of a weaker and a stronger reading. The weaker reading permits and the stronger reading forbids one to be in a state of doubt and of belief with respect to the same proposition at the same time. The stronger claim is standardly attributed to Peirce, for textual and philosophical reasons. This paper maintains that this standard construal is excessively strong. It argues that the secondary literature tends to presuppose the strong reading and that it often does so by confusing sufficient conditions for belief with necessary ones. It acknowledges some textual evidence on behalf of the strong reading but maintains that, taken as a whole, the relevant passages are as friendly to the weak as to the strong interpretation of Peirce. The paper then links the doubt–belief theory of “The Fixation of Belief” to the papers on probability that occupy the bulk of the Illustrations of the Logic of Science. It shows that Peirce's discussion of probability, strength of belief, and weight of evidence makes room for confidence, but not belief, to be undermined and thus offers a more flexible version of Peirce's theory of inquiry.