What is Bifurcation?

The presentation of only two alternatives where others exist is called the fallacy of bifurcation. Sometimes known as the ‘black and white’ fallacy, it presents an ‘either/or’ situation when in reality there is a range of options.


If you are not with us, you are against us.

(Some people might think you partly right. Others might be with you on some things, against you on others. The vast majority probably do not care enough to have an opinion at all.)


Some situations in life have infinite gradations; others offer a straightforward choice. There are many intermediate shades between light and dark, but not all that many things between a boy and a girl. The fallacy of bifurcation consists in taking the limited choice of the second class into situations more properly covered by the first.


There are two types of people in this world: the rich and the suckers. Do you want to get rich, or are you happy to remain a sucker?

(In fact there are degrees of richness, as there probably are of suckerdom. You can be rich by comparison with some, but poor when set alongside others. Suckers, too, seem spread across a continuum.)


The mistake is made by the denial of extra choices. In limiting the field, the perpetrator is leaving out of the discussion material which could well influence the outcome. The fallacy this time is caused not by the intrusion of irrelevant material, but by the exclusion of relevant items.

Bifurcation is used to limit choice. Large political parties employ it to squeeze out smaller ones by denying that they are valid options. Fanatics, for and against, use it to flail the vast mass in between who cannot be bothered. Ideologues use it to classify people into one category or another, rather than admit to the vast range of individual opinions.

One of the more irritating uses of the fallacy of bifurcation occurs in the collection of statistical information. Marketing research polls, along with official forms, can only work by assigning people into broad categories. Information is often requested with the answer ‘yes’ or ‘no’ when the individual concerned knows that neither is correct. Personality tests which pose hypothetical situations always grossly underestimate human ingenuity.

Bifurcation often occurs in a dilemma, even though the dilemma itself is a sound form of argument.


If we import goods we send our jobs abroad; if we export goods we send our property abroad. Since we must either export or import, we lose either our jobs or our property.

(But it is not a black-and-white choice. We can import some things, export others.)


Lord Nelson uttered the famous cry:


Westminster Abbey or victory!

(Overlooking the possibility that he might get both; or the option of St Paul’s, where he ended up.)


The greatest use you can make of bifurcation is to offer a choice limited to something very unpleasant or the course you are advocating. Either the audience does what you suggest, or it will be the end of all life on earth as we know it.


Either we paint the door green, or we will be mocked and ridiculed. People will think we have no taste at all, and we’ll become the laughing stock of the whole neighbourhood. I leave the choice up to you; I’m not trying to influence your decision one way or the other.


You must learn to introduce what you consider to be the only possible choice by saying: ‘Well, ladies and gentlemen, it seems we have two possible choices.. .’

The above article is from the book How To Win Every Argument by Madsen Pirie. The article is only for educational and informative purposes to explain and understand formal logic and logical fallacies. It is a great book, definitely worth a read!