MODULE: Fallacies and biases

TUTORIAL F05: Fallacies of inappropriate presumption

Fallacies of inappropriate presumption are cases where we have explicitly or implicitly made an assumption that is not reasonable to accept in the relevant context. Some examples:

Many people like to ask whether human nature is good or evil. This presupposes that there is such a thing as human nature and that it must be either good or bad. But why should these assumptions be accepted and are they the only options available? What if human nature is neither good nor bad? Or what if good or bad nature applies only to individual human beings?
Consider the question "Have you stopped being an asshole?" Whether you answer "yes" or "no", you admit that you are, or have been, an asshole. Presumably you do not want to make any such admission. Better say, "I refuse to answer this question because it has a false presupposition, namely that I was an asshole."

"Same-sex marriage should not be allowed because by definition a marriage should be between a man and a woman." This argument assumes that only a heterosexual conception of marriage is correct. But this begs the question against those who defend same-sex marriages and is not an appropriate assumption to make when debating this issue.