Love and Marriage
Today's fallacy is also known as the 'Black-or-White Fallacy', the 'Excluded Middle', or the 'False Dilemma'. The False Dichotomy is a fallacy of distraction, because it is used to limit the number of options to two, when in reality there are many. The phrases "America: love it or leave it" and "Jesus says you're either with him or against him" are examples of this fallacious reasoning.
Of course, in cases where the two options are in reality the only two options, then this line of reasoning is not fallacious. But when you have two extremes and you're saying that it's got to be one or the other--that there's no middle ground--you need to check your logic.
Suppose you want to buy an iPod and your mom (or wife, depending on who controls your finances ::wink::: ::wink::) says:
"Either you decide that you can afford an iPod with the money you have now, or you decide you are going to do without music for a while."
This seems like sound logic at first glance. But give it a moments thought and you realize that those are not your only two options--not your only two ways of listening to music. You can stream it off the internet, you could listen to your CD player, you could go to a concert, or play your piano. The argument against you offered you two choices, yet while they are legitimate, are not your only two choices.
All That Glitters
Creationists love to use a form of this ruse in the 'fallacy of negation'. Here, they attempt to discredit one side of an argument (say, evolution) in the hopes that the opposition must accept the other side of the argument (say, creationism). This pet ploy is weak because a theory needs to be supported via evidence in favor of it, not via evidence against its alternatives. Any proposition -- not just creationism -- must stand on its own two feet. Even if there is no support for the opposition to a claim, this is NOT justification for the claim itself. Creationism, or theism for that matter, is not the victor "by default". There is no "by default"; you must PROVE your claim.
I can feel this growing into a topic for a different post, so I'll calm down for now. The lesson for today is to be sure and check for a bogus dilemma when forming your argument's statements. Intermediate possibilities often do exist within the spectrum of two extremes.