Peter Suber, "Truth and Validity"
In logic, truth is a property of statements, i.e. premises and conclusions, whereas validity is a property of the argument True premises and a valid argument guarantee a true conclusion. Up: Logic Table of Contents Languages. Add links. The foundation-concepts of deductive logic are explained--truth, validity, and soundness. Unfortunately, Bob Pula's article Validity and Truth did more to cloud the issue At the logic level, the meaning of "true" is best illustrated by truth tables. This is the difference between a premise and a conclusion, not the.
Therefore, tigers are cats. The distinction between truth and validity is the fundamental distinction of formal logic.
You cannot understand how logicians see things until this distinction is clear and familiar. The seven sample arguments above help us establish the following general principles of logic: True premises do not guarantee validity.
Proved by cases 1 and 3 in the table above.
A true conclusion does not guarantee validity. Proved by cases 3 and 7. True premises and a true conclusion together do not guarantee validity. Proved by case 3. Valid reasoning does not guarantee a true conclusion. Proved by case 4.
Validity and Soundness | Internet Encyclopedia of Philosophy
Proved by cases 4 and 6. A false conclusion does not guarantee invalidity. False premises and a false conclusion together do not guarantee invalidity. Each statement in the argument is either a premise, or else follows from the previous statements in the argument. So two kids shouting "'tis" and "'tisn't" at each other does not constitute an argument, neither do two teenagers swearing at each other.
Introduction to Philosophy/Logic/Truth and Validity
This book is here to help you behave like civilized adults. Now sometimes you may see two adults pointing out facts to each other, and making inferences from those facts. We might say that these two adults are 'having an argument'. To be technical, it is a dialectic in which each side advances an argument in the sense meant here. A mathematical argument is called a proof, and the conclusion of the argument is called a theorem.
Sometimes only the really interesting conclusions are known as theorems, and the less important ones are given another name like lemma.
Compare how we use the words 'lady' or 'gentleman' - these words can be reserved to refer only to people of status, or they can be used to refer to everyone. Euclid, in The Elements, starts off with a set of premises from which he derives several volumes of conclusions, all in a rigorous manner. Such premises are known as 'axioms'.
Validity and Truth
Logicians are trying to do something similar with arguments. We are reasoning about reasoning.
In arguments, mathematical or otherwise, each statement should be intuitively obvious given what has been said before - this is what is meant when we say that one statement follows from its predecessors. Logicians have tried to replace this appeal to the 'intuitively obvious' with a set of rules, called rules of inference, which form a special class of axiom.