Error has sometimes been called privation or _negativity._ It is commonly defined as a thinking of the false, as the non-conformity of thought with its object, and in other similar ways. These are all reducible to the first, since, for example, thought which is of a different form from its object is false thought, which does not attain to its intrinsic end; and false thought is not thought, but privation of thought, negativity. As negativity error gives rise to a negative concept, responding to the positive concept, which is truth. True and false, truth and error, are related to one another as opposite concepts. Now we know from the logical doctrines just stated that opposite concepts, far from being separable, are not even distinguishable, and when they are distinguished, they represent nothing but the abstract division of the pure concept, of the unique concept, which is the synthesis or dialectic of opposites. And we know from the whole of Philosophy that Reality, thought in the pure concept and of which the pure concept is also an integral element, genuine and truly real Reality, is a perpetual development and progress, which is rendered possible by the negative term intrinsic to the positive and constituting the mainspring of its development. If then, error is negativity, it is vain to treat it as something positive. No other positivity or reality belongs to it than just negativity, which is a moment of the dialectic synthesis and outside the synthesis is nothing. A treatment of error in this sense already exists quite complete in the treatment of logical truth; and there is nothing special to add here to that argument. As a fact, a form of the spirit distinguishable from the positive and real forms, error does not exist, and philosophy cannot philosophize upon what is not. [Sidenote: _Positive and existing errors._] Nevertheless, we all know errors, distinguishable from truth and existing for themselves. The evolutionist affirms the biological formation of the _a priori_; the utilitarian resolves duty into individual interest; the Christian says that God the Father sent his son Jesus to redeem men from the perdition into which they had fallen through the sin of Adam; the Buddhist preaches the annulment of the Will. Are not these true and proper errors? Have they perchance no existence? Have they not been expressed, repeated, listened to, believed? Whoever does not admit the validity of the examples adduced can himself find others; there will certainly be no lack of examples in such a field. Do we wish to maintain that these errors do not exist, in homage to the definition of error as negativity and unreality? They may not exist as truth, but they may perfectly well exist as errors. [Sidenote: _Positive errors as practical acts._]