FORMAL LOGIC - ITS SCOPE AND LIMITS

The tree method is elaborated in manageable steps over five chapters, in each of which its adequacy is reviewed; soundness and completeness proofs are extended at each step, and the decidability proof is extended at the step from truth functions to the logic of nonoverlapping quantifiers with a single variable, after which undecidability is demonstrated by example. The first three chapters are bilingual, with arguments presented twice, in logical notation and in English. The last three chapters consider the discoveries defining the scope and limits of formal methods that marked logic's coming of age in the 20th century: Godel's completeness and incompleteness theorems for first and second-order logic, and the Church-Turing theorem on the undecidability of first-order logic.