Logical intelligence: syllogism

A lot of IQ tests use questions of the syllogism type. The syllogism consists of two related propositions which allow for a conclusion. The question is which is the right conclusion. The syllogism relies on the ability to reason logically.

For example:

  1. All cats have fleas.
  2. Fleas are red.

Which conclusion can be drawn with absolute certainty from these two statements?

  • All fleas are on cats
  • All cats have red fleas
  • Cats can sometimes have black fleas
  • Dogs never have red fleas

The right answer is: All cats have red fleas. After all: all cats have fleas and all fleas are red. The other propositions are untrue or the truth is not certain. For example, other animals can also have fleas and fleas cannot have another color than red.

Want to come up with your own syllogism?

If you want to come up with your own syllogism, you have to make up propositions that have an indirect relationship. The indirect relationship should be contained in the right answer.

It is important that the wrong answers are wrong, but still (slightly) plausible. They have to contain aspects (for example, fleas, cats, red) from one or both propositions, but should still be wrong. If that is not the case, the syllogism test question becomes too easy.

Another type of IQ test questions is rotating shapes. You can also take an IQ test.