illogical

Everyday

1. Illogical means not making sense, or not following the rules of good reasoning. tree →
2. Illogical describes a feeling or action that has no good reason behind it. tree →

In the lessons

In maths and logic lessons an illogical step is one where the conclusion does not follow from the facts. In everyday life people call fears or rules illogical when they cannot see a reason. In stories a character such as Mr Spock in Star Trek says «Illogical» to point out muddled thinking. Phrases: «totally illogical», «it is illogical to», «an illogical fear».

Examples

• It is illogical to wear sunglasses to read in the dark. tree →
• His argument was illogical because it contradicted itself. tree →
• I know my fear of spiders is illogical, but I still scream. tree →
• Saying «all cats are pets, so all pets are cats» is illogical. tree →
• The rule seemed illogical until the teacher explained it. tree →
• Mr Spock raised an eyebrow and said, «Illogical.» tree →
• Changing the answer without checking was an illogical move. tree →

Note

Prefix «il-» before «l» means «not»: illegal, illegible, illogical. Not the same as «untrue»: a sentence can be logical but untrue. In maths reasoning, «if A then B» does not mean «if B then A»; mixing them up is illogical.