Syllogisms are a type of logical reasoning often used in philosophical arguments. Logical reasoning involves abstract thinking: you approach a problem by organizing a series of steps (called premises) into a particular order
Syllogisms are the most common way of arranging premises into a good argument. A syllogism is a form of deductive argument where the conclusion follows from the truth of two (or more) premises. A deductive argument moves from the general to the specific and opposes inductive arguments that move from the specific to the general:1
- All mammals are animals.
- Camels are mammals.
- Therefore, camels are animals.
As long as premise one and premise two are true, then the conclusion must also be true. If mammals are animals, and camels are mammals; there is no way camels aren’t animals!
Usually, syllogisms have three-parts – two premises and a conclusion – although “syllogism” is sometimes used to refer to any deductive argument.
The first premise is called the “major premise;” the second premise is called the “minor premise.” Universal syllogisms, like the one above, use all-encompassing words, such as ‘all’, or ‘only’. Particular syllogisms, on the other hand, are only about some things: 2
- No humans are immortal.
- Some organisms are immortal.
- Therefore, some organisms aren’t humans.
However, we must remember that only when both premises are true can the argument be sound. A syllogism may state that all birds can fly, penguins are birds, and therefore, penguins can fly. Though the argument is logically valid, it includes a false premise (all birds can fly), making the argument unsound.