And yet, after we have denied the logical existence of error, we are still confronted with the mass of positive errors which we can more or less easily identify in the course of history and in our daily experience. Positive errors, that is, affirmations of knowing that which we do not know, are real products of our activity: but since the theoretical value, truth, is absent from them, they cannot be products of the theoretical activity. They must therefore be products of the only other form of spiritual activity, the practical. Ignorance or obscurity or doubt are not errors; they are the inexhaustible matter to which the spirit of man is perpetually giving form and reality. To be aware of one's ignorance is in fact the first stage in the research of truth, the _initìum sapientæ_. Thought and truth are affirmation; the positive error is an affirmation also, which simulates truth. We cannot think an error, but we can pass from thought to action, by making a false affirmation, a purely practical affirmation, which consists in the act of producing sounds to which no thought corresponds, or, which amounts to the same, only a thought without value, without coherence, without truth. What we have qualified in its negative aspect as a theoretical error manifests itself in its positive aspect as an act of will, directed to a certain end, a practical act, and, as such, having its own rationality, which is neither logical, nor moral, but purely economic, consisting in the adequacy of that particular affirmation to the individual purpose by which it has been prompted. Morality requires that the thinking spirit should realize itself as truth; and therefore the economic act which is error, though logically unreal, though economically useful, finds inevitably its ultimate sanction in a moral condemnation.
Though this doctrine may appear unfamiliar to the logician, yet we all constantly depend on it in our analysis of error. We know that error is due to the passions or interests of men, which cloud the intellect, and the more an error is foreign to our own ways of thinking, the easier it is for us to discover the practical motives which help us to explain it away. That category of errors which goes under the name of national prejudices, for instance, is transparent in its origins to every man belonging to a nation other than the one in which a particular set of such prejudices is commonly accepted. And other categories of errors, social, professional, religious, and so on, are of the same kind, affecting only certain classes of men, because of the passions or interests or traditions which belong to them by reason of their peculiar practical associations. In the field of politics, or in any kind of heated discussion, this research of the practical motive is even pushed to the extreme, and the bad faith of the adversary becomes an obvious axiom. In such cases, the same passions being active on both sides, the research of the practical motive is evidently not pure and disinterested, but is itself moved by a practical motive, and therefore likely to produce a new error, rather than a clear judgment. Therefore, though rigorously speaking there is no difference between the error which is a deliberate lie and that which is due to a more or less justifiable weakness, and there is no error which is not in bad faith, which is not due to a deliberate act of will, yet, from an empirical standpoint we may distinguish between errors in bad and in good faith, and recommend tolerance and indulgence for the latter kind. But tolerance is not indifference. Croce went so far, in drawing the consequences of his doctrine, as to justify the Holy Inquisition; and in fact all our modern advocates of religious and political tolerance have really shaken our faith in its methods, but not in its principle, which is that of the moral responsibility of error. The Holy Inquisition moreover was bound to clash with the freedom, which is not the freedom of error but the freedom of truth, because it placed its faith in a static, extrahuman truth, as against the veritas _filia temporis_, the truth which is engendered and conditioned by history, by the peculiar problems and intellectual climate of the age, and which is the object of our modern faith; and therefore defeated its own end by striking at the roots of the value for the upholding of which it had been established.