Whether you call it bifurcation, either/or fallacy, black and white fallacy, or simply false dilemma it is the same beast. There are only two choices presented when this fallacy is committed. It is the fallacy committed by assuming that a distinction is exhaustive and exclusive when other alternatives exist. I believe the reason this fallacy is seen so often is the number of bipolar terms we use, rich/poor good/bad tall/short normal/abnormal right/wrong although there are numerous gradations between these extremes. When you discover this fallacy in someone else's argument (could be your argument as well) there is a temptation to just scream false dilemma you moron. Of course if you were hoping to persuade or even engage in a spirited debate its already too late. Most people react in a predictable way to such pronouncements. It is an art to point out the error in a way that preserves good will and also makes your point. I recently saw a lovely example of this. Mike Sanders and Joseph Duemer are two of the more thoughtful members of the blogging community. Both are articulate and both polite. They have been discussing the Israeli Palestinian conflict and both have made good points. In a recent post Joseph said "Mike Sanders quoted the callow Norah Vincent a while back, regarding the Middle East, saying "There are only two sides, take your pick." I'd like to recast that choice: You can either be a partisan of one side or the other, or you can look for a humane & moral solution. There are only two choices--take your pick." A clever way to point out the false dilemma not by screaming idiot, but showing that there were more than the two choices Norah had posed. Genuine "either-or" situations are very rare. If you come across this type of argument you have every reason to be skeptical. You will almost always discover that there are additional alternatives that have been ignored by the arguer. Once you have discovered all the relevant alternatives the question becomes which is best supported by the available evidence.