This fallacy arises when we illegitimately limit the number of alternatives available.


1) You must be a Republican or Democrat. You are not a Democrat. Therefore, you must be a Republican.

The problem is the options are illegitimately limited; you could be a libertarian, anarchist, or socialist.

The premise for this fallacy is common:

Either support this bill or be unpatriotic. Either buy this car or be unhappy. Either vote for this law or be a Nazi. Either support all forms of abortion or be against all forms. You must support dualism or materialism. Either absolutely prove your point or it is all relative. Strong artificial intelligence is possible now or never. The president is either a genius or an idiot. It is always wrong to lie or it is never wrong to lie. I need an A or my life will be ruined.


It is important to remember that sometimes there really are limited options. For example, the following premises really do present a limited number of alternatives:

  • I am either alive or dead.
  • God either exists or does not exist.
  • 2+2 equals 4 or it does not equal 4.

Keep in mind that people may use different names for the black and white thinking fallacy: false dilemma, false dichotomy, and the either/or fallacy, but they are all pretty much synonymous.

Cognitive therapists call it polarized thinking, and it often arises in therapy. For example, I might believe I am either a complete success or a complete failure, that everyone is for me or against me, or that each person is either entirely good or bad. The therapist can help me see how these fallacious forms of thinking cause destructive emotions. The stoics also recognized this and were, in a way, the first cognitive therapists. In short, logical thinking is one key to mental health.

How to avoid

Think about each situation to identify whether there really are a limited number of options. Do not rely on emotion alone, which often sees in black and white.


  1. Create or find some examples of this fallacy.
  2. For what conscious and subconscious reasons do we artificially limit our options?
  3. Is the “us/them” mentality a form of black and white thinking?
  4. How could an unethical salesperson use this fallacy to persuade?


  1. Answers will vary.
  2. According to Peg Tittle in Critical Thinking: An Appeal to Reason (2011), one reason people fall for this fallacy is because they lack imagination and cannot see more than two alternatives. Another reason people use this fallacy is to make it seem as though there is only one opposing and awful solution. If that is the only option, then any other solution looks good in comparison!
  3. Arbitrarily dividing the world into superior us and inferior them is the source of much evil and suffering. One of the causes of this type of thinking is seeing others as entirely good or bad.
  4. Answers will vary.

Return to Logic Home Page         Go to Next Fallacy in Chapter 3         Go to Chapter 4 (S Method)