There are, then, syntactical problems in the fields of perceptual signs, aesthetic signs, the practical use of signs, and general linguistics which h… - Charles W. Morris

Empirical problems of a nonlinguistic sort are not solved by linguistic considerations, but it is important that the two kinds of problems not be confused and that nonlinguistic problems be expressed in such a form as aids their empirical solution.

Semiotic provides a basis for understanding the main forms of human activity and their interrelationship, since all these activities and relations are reflected in the signs which mediate the activities ... In giving such understanding, semiotic promises to fulfil one of the tasks which traditionally has been called philosophical. Philosophy has often sinned in confusing in its own language the various functions which signs perform. But it is an old tradition that philosophy should aim to give insight into the characteristic forms of human activity and to strive for the most general and the most systematic knowledge possible. This tradition appears in a modern form in the identification of philosophy with the theory of signs and the unification of science, that is, with the more general and systematic aspects of pure and descriptive semiotic.

The process in which something functions as a sign may be called . This process, in a tradition which goes back to the Greeks, has commonly been regarded as involving three (or four) factors: that which acts as a sign, that which the sign refers to, and the effect on some interpreter in virtue of which the thing in question is a sign to that interpreter. These three components in semiosis may be called, respectively, the sign vehicle, the designatum, and the interpretant; the interpreter may be included as a fourth factor. These terms make explicit the factors left undesignated in the common statement that a sign refers to something for someone.