The first beginning logic text to employ the tree method—a complete formal system of first-order logic that is remarkably easy to understand and use—this text allows students to take control of the nuts and bolts of formal logic quickly, and to move on to more complex and abstract problems.This new edition provides additional problems, solutions to selected problems, and two new Supplements: “Truth-Functional Equivalence” reinstates material on that topic from the second edition that was omitted in the third, and “Variant Methods, in which John Burgess provides a proof regarding the possibility of modifying the tree method so that it will always find a finite model when there is one, and another, which shows that a different modification—once contemplated by Jeffrey—can result in a dramatic speed-up of certain proofs.