An argument connects one or more premises to a conclusion. This subtopic covers deductive and inductive arguments, the syllogism, and validity.
Premises and conclusion
A premise is a statement offered as evidence or a reason. The conclusion is the statement that the premises are meant to support. Words such as "therefore", "hence" and "so" usually signal a conclusion.
Example
Premise 1: All humans are mortal. Premise 2: Socrates is human. Conclusion: Therefore, Socrates is mortal.
Deductive vs inductive
A deductive argument reasons from general statements to a specific conclusion; if the premises are true and the form is valid, the conclusion must be true. An inductive argument reasons from specific cases to a general conclusion, which is only probable.
- Deductive: general → specific (certain when valid).
- Inductive: specific → general (probable).
Syllogism and validity
A syllogism is a deductive argument with exactly two premises and one conclusion.
Key formula
$\text{All } A \text{ are } B,\;\; \text{All } B \text{ are } C \;\;\Rightarrow\;\; \text{All } A \text{ are } C$
An argument is valid when the conclusion follows logically from the premises — regardless of whether the premises themselves are actually true.
Remember
Deduction gives certainty; induction gives likelihood. A syllogism always has two premises.