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[TUTORIAL F04] Insufficiency

Fallacies of insufficiency are cases where insufficient evidence is provided in support of aclaim. Probably most common fallacies fall within this category.

Limited sampling

Momofuku Ando, the inventor of instant noodles, died at the age of 96. He said heate instant noodles everyday. So instant noodles cannot be bad for your health.

A black cat crossed my path this morning, and I got into a traffic accident thisafternoon. Black cats are really unlucky.

In both cases the observations are relevant to the conclusion, but a lot more data is neededto support the conclusion, e.g. Studies show that many other people who eat instant noodleslive longer, and those who encounter black cats are more likely to suffer from accidents.

Appeal to ignorance

We have no evidence showing that he is innocent. So he must be guilty.

If someone is guilty, it would indeed be hard to find evidence showing that he is innocent. Butperhaps there is no evidence to point either way, so lack of evidence is not enough to proveguilt.

Naturalistic fallacy

Many children enjoy playing video games, so we should not stop them fromplaying.

Many naturalistic fallacies are examples of fallacy of insufficiency. Empirical facts by

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themselves are not sufficient for normative conclusions, even if they are relevant.

F04.1 Exercises

There are many other kinds of fallacy of insufficiency. See if you can identify some of them.