Syllogism
What is Syllogism?
A syllogism is a form of deductive reasoning in which a conclusion is drawn from two or more premises. This logical structure consists of three parts: a major premise, a minor premise, and a conclusion. The major premise presents a general statement, the minor premise presents a specific statement, and the conclusion logically follows from the two premises.
The Basic Idea
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.
A syllogism is valid (or logical) when its conclusion follows from its premises. A syllogism is true when it makes accurate claims – that is, when the information it contains is consistent with the facts. To be sound, a syllogism must be both valid and true. However, a syllogism may be valid without being true or true without being valid.
– Professors of English Laurie J. Kirszner and Stephen R. Mandell in their grammar and composition exercise textbook,The Concise Wadsworth Handbook3
About the Authors
Dan Pilat
Dan is a Co-Founder and Managing Director at The Decision Lab. He is a bestselling author of Intention - a book he wrote with Wiley on the mindful application of behavioral science in organizations. Dan has a background in organizational decision making, with a BComm in Decision & Information Systems from McGill University. He has worked on enterprise-level behavioral architecture at TD Securities and BMO Capital Markets, where he advised management on the implementation of systems processing billions of dollars per week. Driven by an appetite for the latest in technology, Dan created a course on business intelligence and lectured at McGill University, and has applied behavioral science to topics such as augmented and virtual reality.
Dr. Sekoul Krastev
Sekoul is a Co-Founder and Managing Director at The Decision Lab. He is a bestselling author of Intention - a book he wrote with Wiley on the mindful application of behavioral science in organizations. A decision scientist with a PhD in Decision Neuroscience from McGill University, Sekoul's work has been featured in peer-reviewed journals and has been presented at conferences around the world. Sekoul previously advised management on innovation and engagement strategy at The Boston Consulting Group as well as on online media strategy at Google. He has a deep interest in the applications of behavioral science to new technology and has published on these topics in places such as the Huffington Post and Strategy & Business.
