It is a commonplace belief that many beliefs, e.g. religious convictions, are a purely private matter, and this is meant in some way to serve as a defense against certain forms of criticism. In this paper it is argued that this thesis is false, and that belief is really often a public matter. This argument, the publicity of belief argument, depends on one of the most compelling and central thesis of Peircean pragmatism. This crucial thesis is that bona fide belief (...) cannot be separated from action. It is then also suggested that we should accept a form of W. K. Clifford's evidentialism. When these theses are jointly accepted in conjunction with the basic principle of ethics that it is prima facie wrong to act in such a way that may subject others to serious but unnecessary and avoidable harm, it follows that many beliefs are morally wrong. (shrink)