In this comparative historical analysis, we will analyze the intellectual tendency that emerged between 1946 and 1956 to take advantage of the popularity of communication theory to develop a kind of informational epistemology of statistical mechanics. We will argue that this tendency results from a historical confluence in the early 1950s of certain theoretical claims of the so-called English School of Information Theory, championed by authors such as Gabor (1956) or MacKay (), and from the attempt to extend the profound success of Shannon's ([1948] 1993) technical theory of sign transmission to the field of statistical thermal physics. As a paradigmatic example of this tendency, we will evaluate the intellectual work of Léon Brillouin (), who, in the mid-fifties, developed an information theoretical approach to statistical mechanical physics based on a concept of information linked to the knowledge of the observer.