The Logic exists in two versions, the Science of Logic, which Hegel first published in 1812–16 and partially revised for a second edition just before his death; and the first part of the system of Science, often called the Encyclopaedia, published first in 1817 and afterwards revised as well. I shall draw on both of these (respectively WL and EL) in what follows.

The Logic is the second of the great derivations of Hegel's vision, and a crucial one as we have seen, because it is the only real candidate for the role of strict dialectical proof. If the real exists and has the structure it has by conceptual necessity, then the task of the Logic is to show this conceptual structure by pure conceptual argument.

This may sound mad to ordinary consciousness and indeed to most philosophers. For we think of our concepts as instruments of our thought which may or may not apply adequately to reality. We start off, that is, with a notion of thought as over against the world about which we think. This dualism is linked to another; since a concept or a category is thought of as a universal which can apply to many contents, we are tempted to think of it as an abstract form over against the sensible contents to which it applies.