The Commens Dictionary
Quote from ‘Short Logic: Chapter I. Of Reasoning in General’
An icon is a sign which stands for its object because as a thing perceived it excites an idea naturally allied to the idea that object would excite. Most icons, if not all, are likenesses of their objects. [—] It may be questioned whether all icons are likenesses or not. For example, if a drunken man is exhibited in order to show, by contrast, the excellence of temperance, this is certainly an icon, but whether it is a likeness or not may be doubted. The question seems somewhat trivial.
Peirce often used the term "likeness" instead of "icon", especially in the 1890s. However, as Peirce refined his notion of the icon (and defined it in terms of pure Firstness or possibility) he increasingly preferred "icon", at times suggesting that "likeness" does not cover exactly the same semiotic terrain as "icon". This possible distinction between likeness and icon has often been overlooked, perhaps because of errors in the Collected Papers. Judging by the available evidence, the editors of the Collected Papers now and then substituted "icon" for Peirce's "likeness", (see e.g. CP 2.299 and EP 2:9). On the other hand, the distinction between "icon" and "likeness" is not strictly adhered to by Peirce himself; as he suggests, the whole question may be somewhat trivial. MB