Definition
Logical form is the structure of an argument once its particular subject matter has been stripped away, leaving only the logically significant skeleton — the connectives, quantifiers, and the pattern in which terms recur. It is the answer to the question "what shape is this argument?" rather than "what is it about?"
Two arguments can speak of completely different things yet share one form. "All dogs are mammals; Rex is a dog; so Rex is a mammal" and "All primes are integers; 7 is a prime; so 7 is an integer" are the same argument logically. Their common form is what logic actually studies.
Why it matters
How it works
To expose logical form, a logician replaces the specific content of an argument with schematic letters and standard symbols — for instance writing a conditional as A → B, or a generalisation with a quantifier such as ∀x. What survives the substitution is the form; what is discarded is the content.
Priest highlights that finding the right form is itself a substantive task. Ordinary sentences are often logically slippery: "Everyone loves someone" has two distinct readings, each a different form. Choosing the correct formalisation is half the work of applying logic, because validity is decided only once the form is fixed.