Of the two parts of this paper the first is a study in formal analysis. It attempts to show that there is no problem, logically speaking, of the existence of an external world. Its point is to show that the very attempt to state the problem involves a self-contradiction: that the terms cannot be stated so as to generate a problem without assuming what is professedly brought into question. The second part is a summary endeavor to state the actual question which has given rise to the unreal problem and the conditions which have led to its being misconstrued. So far as subject-matter is concerned, it supplements the first part; but the argument of the first part in no way depends upon anything said in the second. The latter may be false and its falsity have no implications for the first. I There are many ways of stating the problem of the existence of an external world. I shall make that of Mr. Bertrand Russell the basis of my examinations, as it is set forth in his recent book _Our Knowledge of the External World as a Field for Scientific Method in Philosophy_. I do this both because his statement is one recently made in a book of commanding importance, and because it seems to me to be a more careful statement than most of those in vogue. If my point can be made out for his statement, it will apply, a fortiori, to other statements. Even if there be those to whom this does not seem to be the case, it will be admitted that my analysis must begin somewhere. I cannot take the space to repeat the analysis in application to differing modes of statement with a view to showing that the method employed will yield like results in all cases. But I take the liberty of throwing the burden upon the reader and asking him to show cause why it does not so apply. After rejecting certain familiar formulations of the question because they employ the not easily definable notions of the self and independence, Mr. Russell makes the following formulation: Can we "know that objects of sense ... exist at times when we are not perceiving them?" (_op. cit._, p. 75). Or, in another mode of statement: "Can the existence of anything other than our own[63] hard data be inferred from the existence of those data?" (pp. 73 and 83).