False Dilemma Fallacy

Summary and Explanation


Fallacy Name:
False Dilemma

Alternative Names:
Excluded Middle
False Dichotomy

Fallacy Category:
Fallacies of Presumption > Suppressed Evidence



The False Dilemma fallacy occurs when an argument offers a false range of choices and requires that you pick one of them. The range is false because there may be other, unstated choices which would only serve to undermine the original argument.

If you concede to pick one of those choices, you accept the premise that those choices are indeed the only ones possible. Usually, only two choices are presented, thus the term "False Dilemma"; however, sometimes there are three (trilemma) or more choices offered.

This is sometimes referred to as the "Fallacy of the Excluded Middle" because it can occur as a misapplication of the Law of the Excluded Middle. This "law of logic" stipulates that with any proposition, it must be either true or false; a "middle" option is "excluded". When there are two propositions, and you can demonstrate that either one or the other must logically be true, then it is possible to argue that the falsehood of one logically entails the truth of the other.

That, however, is a tough standard to meet - it can be very difficult to demonstrate that among a given range of statements (whether two or more), one of them absolutely has to be correct.

It certainly isn't something which can simply be taken for granted, but this is precisely what the False Dilemma Fallacy tends to do.

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This fallacy can be considered a variation on the fallacy of Suppressed Evidence. By leaving out important possibilities, the argument is also leaving out relevant premises and information which would lead to better evaluation of the claims.

Usually, the False Dilemma fallacy takes this form:

  • 1. Either A or B is true. A is not true. Therefore, B is true.

As long as there are more options than A and B, then the conclusion that B must be true cannot follow from the premise that A is false.

This makes an error similar to that found in the fallacy of Illicit Observation. One of the examples of that fallacy was:

  • 2. No rocks are alive, therefore all rocks are dead.

We can reword it to:

  • 3. Either rocks are alive or rocks are dead.

Whether phrased as an Illicit Observation or as a False Dilemma, the error in these statements lies in the fact that two contraries are presented as if they were contradictories. If two statements are contraries, then it is impossible for both of them to be true, but it is possible for both to be false. However, if two statements are contradictories, it is impossible for them to both be true or both be false.

Thus, when two terms are contradictories, the falsehood of one necessarily implies the truth of the other. The terms alive and lifeless are contradictories - if one is true, the other must be false. However, the terms alive and dead are not contradictories; they are, instead, contraries.

It is impossible for both to be true of something, but it is possible for both to be false - a rock is neither alive nor dead because "dead" assumes a prior state of being alive.

Example #3 is a False Dilemma fallacy because it presents the options alive and dead as the only two options, on the assumption that they are contradictories.

Because they are actually contraries, it is an invalid presentation.

« Explanation | Paranormal Examples »

Belief in paranormal events can easily proceed from a False Dilemma Fallacy:

  • 4. Either John Edward is a con-man, or he really can communicate with the dead. He seems too sincere to be a con-man, and I'm not so gullible that I can be easily fooled, therefore he communicates with the dead and there is an afterlife.

Just such an argument was often made by Sir Arthur Conan Doyle in his defenses of spiritualists.

He, like so many of his time and ours, was convinced of the sincerity of those who claimed to be able to communicate with the dead, just as he was convinced of his own superior abilities to detect fraud.

The argument above actually contains more than one False Dilemma. The first and most obvious problem is the idea that Edward must either be lying or genuine - it ignores the possibility that he has been fooling himself into thinking that he has such powers.

A second False Dilemma is the unstated assumption that either the arguer is very gullible or can quickly spot a fake. It may be that the arguer is indeed good at spotting fakes, but doesn't have the training to spot fake spiritualists. Even skeptical people assume that they are good observers when they aren't - that's why trained magicians are good to have in such investigations. Scientists have a poor history of detecting fake psychics because in their field, they are not trained to detect fakery - magicians, however, are trained in exactly that.

Finally, in each of the false dilemmas, there is no defense of the option which is rejected. How do we know that Edward isn't a con-man? How do we know that the arguer isn't gullible? These assumptions are just as questionable as the point under contention, so assuming them without further defense results in begging the question.

Here is another example which uses a common structure:

  • 5. Either scientists can explain the strange objects seen in the sky over Gulf Breeze, Florida, or these objects are piloted by visitors from outer space. Scientists cannot explain these objects, so they must be visitors from outer space.

This sort of reasoning actually leads people to believe many things, including that we are being watched by extraterrestrials. It is not uncommon to hear something along the lines of:

  • 6. If scientists (or some other authority) cannot explain event X, then it must be caused by (insert something unusual - aliens, ghosts, gods, etc.).

But we can find serious fault with this reasoning even without denying the possibility of gods or ghosts or visitors from outer space. With a little reflection we can realize that it is quite possible that the unexplained images have ordinary causes that scientific investigators have failed to discover. Additionally, perhaps there is a supernatural or paranormal cause, but not the one being offered.

In other words, if we think a little bit deeper, we can realize that the dichotomy in the first premise of this argument is false. Digging deeper will also often reveal that the explanation being offered in the conclusion does not fit the definition of explanation very well anyway.

This form of the False Dilemma fallacy is very similar to the Argument from Ignorance (Argumentum ad Ignorantium). Whereas the false dilemma presents the two choices of either scientists know what is going on or it must be supernatural, an appeal to ignorance simply draws conclusions from our general lack of information on the topic.

« Examples and Discussion | Religious Examples »

The False Dilemma Fallacy can come very close to the Slippery Slope fallacy. Here is an example from the forum illustrating that:

  • 7. Without God and the Holy Spirit we all have our own ideas of what is right and wrong, and in a democratic system the majority opinion determines right and wrong. Someday they might vote in that there can only be so many kids per household, like in China. Or they can take guns away from citizens. If people don't have the Holy Spirit to convict them of what sin is, anything can happen!

    The last statement is clearly a False Dilemma - either people accept the Holy Spirit, or an "anything goes" society will be the result. There is no consideration given to the possibility of people creating a just society on their own.

    The main body of the argument, however, could either be described as a False Dilemma or as a Slippery Slope fallacy. If all that is being argued is that we must choose between believing in a god and having a society where the government dictates how many children we are allowed to have, then we are being presented with a false dilemma.

    However, if the argument is actually that rejecting belief in a god will, over time, lead to worse and worse consequences, including the government dictating how many children we may have, then we have a Slippery Slope Fallacy.

    There is a common religious argument, formulated by C. S. Lewis, which commits this fallacy and is similar to the above argument regarding John Edward:

    • 8. A man who was merely a man and said the sort of things Jesus said would not be a great moral teacher. He would either be a lunatic - on the level with a man who says he is a poached egg - or he would be the devil of hell. You must take your choice. Either this was, and is, the Son of God, or else a madman or something worse. You can shut Him up for a fool or you can fall at His feet and call Him Lord and God. But let us not come with any patronizing nonsense about His being a great human teacher. He has not left that open to us.

      This is a trilemma, and has become known as the "Lord, Liar or Lunatic Trilemma" because it is repeated so often by Christian apologists. By now, however, it should be clear that just because Lewis has only presented us with three options does not mean we have to sit by meekly and accept them as the only possibilities.

      Yet we cannot merely claim that it is a false trilemma - we have to come up with alternative possibilities while the arguer demonstrates that the above three exhaust all possibilities. Our task is easier: Jesus might have been mistaken. Or Jesus was severely misquoted. Or Jesus has been grossly misunderstood. We have now doubled the number of possibilities, and the conclusion no longer follows from the argument.

      If someone offering the above wishes to continue, she must now refute the possibility of these new alternatives. Only after it has been shown that they are not plausible or reasonable options can she return to her trilemma. At that point, we will have to consider whether still more alternatives can be presented.

      « Paranormal Examples | Political Examples »

      No discussion of the False Dilemma Fallacy can ignore this famous example:

      • 9. America, love it or leave it.

      Only two options are presented: leaving the country, or loving it - presumably in the way that the arguer loves it and wants you to love it. Changing the country is not included as a possibility, even though it obviously should be. As you might imagine, this sort of fallacy is very common with political arguments:

      • 10. We must deal with crime on the streets before improving the schools.
        11. Unless we increase defense spending, we will be vulnerable to attack.
        12. If we don't drill for more oil, we will all be in an energy crisis.

      There is no indication that alternative possibilities are even being considered, much less that they might be better than what has been offered. Here is an example from the Letters to the Editor section of a newspaper:

      • 13. I don't believe any sympathy should be offered to Andrea Yates. If she were really that seriously ill, her husband should have had her committed. If she wasn't ill enough to be committed, then she was obviously sane enough to have made the decision to distance herself from her children and seek mental help with determination. (Nancy L.)

      Clearly there are more possibilities than what are offered above. Perhaps no one noticed how bad she was. Perhaps she suddenly got much worse.

      Perhaps a person sane enough not to be committed is not also sane enough to find help on her own. Perhaps she had too great a sense of duty towards her family to consider distancing herself from her children, and that was part of what led to her breakdown.

      The False Dilemma Fallacy is unusual, however, in that it is rarely sufficient to merely point it out.

      With the other Fallacies of Presumption, demonstrating that there are hidden and unjustified premises should be enough to get the person to revise what they have said.

      Here, however, you need to be willing and able to offer alternative choices which have not been included. Although the arguer should be able to explain why the offered choices exhaust all possibilities, you will probably have to make a case yourself - in doing so, you will be demonstrating that the terms involved are contraries rather than contradictories.

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