Whenever I hear or read something along the lines of “well, that’s like saying …” uttered as a throwaway put-down, without exception I find myself silently responding “no it fucking well isn’t.” I have a huge problem with people using analogy in the realm of argument, because it seems to fundamentally misunderstand what analogy is for, and as a consequence it misapplies it. One problem here is that most assume all discourse takes place within the same logical realm. What this doesn’t allow is that the lines between rhetoric and philosophy are fluid, and accordingly their respective logics may mix though without attention being drawn to this. The person making a point in an argument wants to sound like they are speaking from an impregnable position, and accordingly they sheath themselves in the condom of a yes/no binary logic (phallogocentrism alert…insert your prophylactic of choice). Analogy is not party to such a logic of identity. The logic of analogy, if we may call it such, is the logic of possibility.
Analogy works when it is employed in the sense of metaphorical discourse. With this, we use analogy in the positive sense, to make connections, to bring the new to touch our awareness of the known. This creates possibility. It is a one-way vector; outwards. Used as it is in most arguments, it is the words of rhetoric, operating without regard for whether it is valid or not. Analogy used destructively, or even to clarify a position, is not a party to the logic of possibility, nor is it a party to the logic of identity, and thus it is invalid. If somebody is to use analogy in an argument, I would hold that that argument is unsound. Then, for “that’s like saying” to be used, and to hope it supports a point one is making, then you would have to be saying “that is“. You would then be positing identity, holding that “X is Y”. Analogy, for me, is to be avoided as assiduously as the slippery slope, though I am not convinced that I avoid a version of the continuum fallacy myself here. (See lots of other fallacies I am probably guilty of here.)