General Introduction to Logic

I General Overview

1. Initial Description

The word 'logic' comes from the Greek 'λόγος', which means reason or (the) rational. Etymologically, that is logical which is in accord with reason, not merely in the subjective sense, but above all in the objective sense.

In current use of Western languages, the adjective 'logical' signifies what follows an intelligible coherence. Mutatis mutandis, a fact, a product, behavior, a thought, all qualify as 'logical' when these have a certain internal or external order which reason can grasp a posteriori, or of which it is even the original principle. Being essentially tied to intelligibility, the term 'logical' is said principally of thought and then, by derivation, of other realities.

But what does 'a logical thought' mean? Two connotations spring to mind: on the one hand, the rigor of thought itself in its process; on the other, its adherence to the reality of which it is a thought.

In a yet more precise sense, which alone is the interest of this course, 'logical' refers to a particular discipline of philosophical knowing, 'logic', whose mission it is to confer on thought these characteristics of order and truth. St Thomas Aquinas describes the nature of it in this way:

ars quaedam necessaria est, quae sit directiva ipsius actus rationis, per quam scilicet homo in ipso actu rationis ordinate, faciliter et sine errore procedat. Et haec ars est Logica, idest rationalis scientia. (EPA, proem., nn. 1-2)

an art is needed to direct the act of reasoning, so that by it a man when performing the act of reasoning might proceed in an orderly and easy manner and without error. And this art is logic, i.e., the science of reason. (EPA, proem., nn. 1-2)

This text presents us with the scope of the "material" on which this special "art" which we call logic works. Let us unpack its meaning.