Jacob’s Reviews > Logic: A Very Short Introduction > Status Update

Woof my head hurts.

Modern logic, as the author has orchestrated it, is a lot like math. It has rules for situations and propositions. Similar to algebra.

“A deductively valid inference is one for which there is no situation in which all the preferences are true, but the conclusion is not.”

Inductive validity: “when a premiss has a good reason for the conclusion but it is not completely conclusive.”

Example: “Storm clouds are gathering; so there will be rain.”

Deductive validity: “the premises couldn’t be true without the conclusion also being true.”

“(Logic) is not concerned with whether the premisses of an inference are true or false. That’s someone else’s business. It is interested simply in whether the conclusion follows from the premisses. This is what validity is. The central aim of logic is to understand validity.”

“Logic is the study of what counts as a good reason for what, and why.”