Ex Concessis (Guilt by Association)


The argument attacks a position by pointing out that a person who holds the position is being hypocritical, i.e. that he sometimes acts in ways that could be construed as inconsistent with the position, or holds (or previously held) views that could be construed as inconsistent with the position, or associates with people who act in such ways or hold such views.



The phrase "ex concessis" is a Latin phrase meaning "from what has been conceded." It would seem to refer to an argument that begins with premisses that have already been admitted or granted by the oponent, although in practice it is used to label arguments in which the opponent's "concession" of the premisses is merely assumed or implied, based presumably on their past behavior or opinions, or upon their known associates.



"You environmentalist arguments are worthless. After all, you drive a car, too."


"Vegetarianism is un-American. Hitler was a vegetarian."



Ideas connect together. It is reasonable to expect people to hold consistent beliefs, and it is desirable to hold consistent beliefs ourselves. Moreover, it is reasonable to expect people to act on their beliefs, and it is desirable to act consistently ourselves. Opinions that do not sit comfortably with the rest of our beliefs and actions certainly need to be examined. For this reason, it is not necessarily bad reasoning to question opinions that are held by people with whom we disagree on other matters, or by people who seem to act in a manner than appears inconsistent with the opinions in question.

However, sometimes ideas do not connect together. The Ex Concessis fallacy mimics good reasoning when it implies that two ideas connect together that actually do not. Hitler could have been a vegetarian, but still guilty of heinous crimes. The two are not connected. Schopenhauer's example of this fallacy also illustrates this principle: "If you believe that suicide is morally acceptable, why don't you go kill yourself?" It would certainly be inconsistent of someone to kill himself while believing that suicide is immoral, but there is no inconsistency if he fails to kill himself while holding that suicide is morally permitted. Presumably he also believes that it is also morally permitted to remain alive!


Source: From the essay, "The Art of Controversy" by Arthur Schopenhauer. Essays of Arthur Schopenhauer, trans. T. Bailey Saunders. New York: Willey Book Co., n.d.


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