In the Logical Investigations, Husserl argues that “sign” is an ambiguous word because it refers to two essentially different signitive functions: indication and expression. Indications work in an evidential way, providing information through a direct association of the sign and the presence of an object or state of affairs. Expressions work in a non-evidential way, pointing to possible experiences and displaying that the speaker or someone else has had such experience. In this paper I show that Husserl went back to (...) the distinction between indications and expressions in a much later text, a manuscript from 1931, in order to distinguish between two kinds of communication with different essential features. I call these indicative and expressive communication. My claim is that Husserl’s distinction between these two types of communication is a crucial contribution to the phenomenology of knowledge sharing. In knowledge sharing, we appropriate someone else’s knowledge as someone else’s knowledge. Husserl shows that only expressive communication, and not indicative communication, makes this appropriation possible. Since Husserl argues that only humans use expressive communication, his analysis of indicative and expressive communication is also a contribution to understanding the uniquely human capacity for accumulating knowledge. (shrink)