If pressed to supplement Tweedledee's ostensive definition of logic with a discursive definition of the same subject, I would say that logic is the systematic study of the logical truths. Pressed further, I would say that a sentence is logically true if all sentences with its grammatical structure are true. Pressed further still, I would say to read this book.

Uncritical semantics is the myth of a museum in which the exhibits are meanings and the words are labels. To switch languages is to change the labels.

The totality of our so-called knowledge or beliefs, from the most casual matters of geography and history to the profoundest laws of atomic physics or even of pure mathematics and logic, is a man-made fabric which impinges on experience only along the edges. Or, to change the figure, total science is like a field of force whose boundary conditions are experience.

Logic is an old subject, and since 1879 it has been a great one.

To be is to be the value of a variable.

It is one of the consolations of philosophy that the benefit of showing how to dispense with a concept does not hinge on dispensing with it.

Some may find comfort in reflecting that the distinction between an eliminative and an explicative physicalism is unreal.