It is frequently supposed that there exist propositions of a kind appropriately designatable as “self-contradictory”; and in this paper I propose to examine this supposition. It may first be pointed out that some philosophers use the word “proposition” in such a sense that to say there exist self-contradictory propositions is unquestionably to say what is true. They give it such a usage (which they claim to be its only significant one) as to make it synonymous with “declarative sentence”; so that a self-contradictory proposition would be a sentence of the general form s · ~s, and the supposition (a) that there are self-contradictory propositions would be equivalent merely to the supposition (b) that there are sentences of the form s · ~s. In this sense of “proposition” it seems quite plain that there are self-contradictory propositions. But it is not this usage of “proposition” with which I shall be concerned in this paper; rather, my concern will be with the usage given it, whether significantly or not, by philosophers like Mr. Russell, who hold that propositions are what literally significant declarative sentences stand for, or express.