Apparently, an important point to emphasize these days when introducing logic is that, as J.W. Montgomery states, "The word 'logic' properly has no plural."1 One's focus of study in logic can be on informal or formal logic which divides into many specialty areas. These areas include: syllogistic, propositional, predicate or symbolic logic and mathematical logic as well as modal logic and so on. That's just to name a few. All are concerned with the principles of reasoning. As explained by Ambrose and Lazerowitz, whom J.W.M. also quotes, "Aside from the use of notation which allows for both precise expression and ease in deduction, the only difference between the 'logics' consists in the more accurate and extended analyses symbolic logicians have made of their common subject matter."
Montgomery goes on to say, "Non-Western 'logics' are in reality varieties of the universal system of inference based on the law of contradiction which we in the West designate as "classical" or "symbolic" logic. Citing Bochenski, he notes: "Examples are the syllogism of the Tarka-Samgraha and the Mathurantha's definition of number"
Thus demonstrated are a number of facts relevant to epistemology.
To reject the law of contradiction is to destroy the possibility of knowledge as such, since from a tautology or a contradiction anything whatever follows. To argue against formal logic is to employ formal logic already. Employment of formal logic is justified by the best of all "reasons": sheer necessity. 2As unavoidable and undeniable, one might reasonably ask whether logic couldn't be considered, at least, one foundation for much of what we know.
Basic vocabulary to get acquainted with as one begins a study of logic includes: truth, validity, sound, implication, infer, inference, deduce, deduction, premise, conclusion, tautology, syllogism, fallacy, induction, argument, argument forms.
1. Tractatus Logico-Theologicus 2.22
2. ibid 2.232-2.2323
