False dilemma
This fallacy typically involves asking a question and providing only two possible answers when there are actually far more. It seems to be a favourite of politicians, especially when trying to win support for a none-too-plausible policy. Take this classic example:
You're either with us or against us.
The implicit argument here is that two possible positions exist with regard to the matter at hand: in favour or opposed. If we are not in favour, then, it follows that we must be opposed; and vice versa. The use of such tactics often give us the opportunity of appreciating fine—if overblown—rhetoric, too, like "do you support this war to defend our way of life or are you a cowardly, treasonous blackguard?" To expose the question as a false dilemma, all we need do is show that an alternative response exits. Other names for the same thing are the
black and white fallacy, which immediately calls our attention to the shades of grey that are ignored, or the
bifurcation fallacy.
Take another example:
Either you support lowering taxes or you're content to see this country go to hell in short order.
The person presenting such a choice presumably advocates the lowering of taxes and is offering us a choice of two options. Since the second one seems unpalatable, he or she assumes we will lend our support to the policy. Taking the best possible reading of this situation, we might have the following:
P1: We can lower taxes or the country can go to the devil;
P2: No other options exist;
C: Therefore, a person not agreeing with lowering taxes is content to see the country fall apart.
Even this does not precisely address the statement as given; for instance, we could hold no opinion at all on the matter, or be insufficiently informed to do so sensibly. These are alternatives, so the choice given is a false dilemma. In the above formulation we could challenge P2, since it seems unlikely that only one policy has been proposed. A single alternative would again make the choice a false dilemma. As before, this is a fallacy of presumption.