CRITICISM. - In the general sense, every philosophical system or tendency that, before constructing knowledge (v.), raises the problem of the value of knowing itself, of its possibilities, conditions, and limits, is called c. As such, it is opposed both to dogmatism, for which the value of knowledge is a presupposition, and to scepticism, which denies in general the possibility of certain knowledge. In the narrower and more proper sense, c. is the formulation and solution which Kant and the systems directly derived from Kantianism gave to the problem of knowledge, and hence to that of metaphysics. In relation to this meaning, c. sometimes denotes every philosophical system that issues in a subjectivist or idealist solution of the problem of knowledge; or, more generally, every tendency which, after Kant, grants the critique of knowledge a preponderant and totalitarian place in the construction of philosophy.
The fundamental lines of Kantian c., the historical result of the confluence of two antagonistic currents, Hume’s empiricism and Wolff’s rationalism, converge upon the essential problem posed at the beginning of the Critique of Pure Reason: how is scientific knowledge possible, or, in another form, how are synthetic a priori judgments possible, that is, judgments in which the predicate expresses an addition to the subject and which are at the same time universal and necessary? Whereas, Kant reflects, mathematics and physics have long since set out along the secure path of science, metaphysics, as appears from its endless internal conflicts, has not yet enjoyed this fortune. Reason must therefore begin again by examining itself, and see whether perhaps the failure of all attempts to construct metaphysics does not depend upon a radical error of method. Indeed, Kant asserts, the error of method exists: physics and mathematics progress because for a long time they have effected a revolution with regard to the parts that belong to the subject and the object in knowledge; in both, reason no longer proceeds in the mere search for an object in itself to which it must conform, but advances with its constructions and principles, scientifically ordering nature. A similar inversion must perhaps be carried out in metaphysics, by supposing that it is not our conceptual knowledge that models itself upon objects, but rather that objects must conform to our knowledge. There then arises the necessity for a critique of pure reason that proceeds to a complete analysis of reason in its a priori structure, in order to discover in it all the elements, laws, and functions that precede every experience, as conditions of scientific knowledge and of experience itself in general (Critica della ragion pura, Italian translation by G. Gentile, 2nd ed., Bari 1940, pp. 15 ff.). Kant undertakes this investigation in transcendental aesthetics, analytics, and dialectics, which establish respectively the a priori forms of sensibility (intuitions), understanding (concepts), and reason (ideas). The result is the new conception of knowledge as a synthetic a priori activity, whereby knowing is no longer simply the apprehension or reception of a given that stands before the subject; rather, the objects of knowledge are constructed within the subject itself, according to the formal elements arising from its transcendental structure, applied to the matter offered by reality. The solution of the Critique also resolves the problem of science: mathematics and physics are possible as sciences because the concepts of the understanding, formal elements of the a priori synthesis and hence of the universal judgments from which these two sciences result, have their own objective and universal field of application, namely, first of all, the pure forms of sensibility (pure mathematics and pure physics), and then the phenomena or sensible representations given to us according to those forms in experience (empirical physics). Metaphysics, on the other hand, as a science, remains beyond the possibilities of human knowledge, because the ideas of reason (the World, the Ego, God), with which metaphysics ought to concern itself, relate to objects (things in themselves, the noumenon) that are neither given nor can ever be given in experience, and of which, consequently, no science is possible: the Ego, the World, and God, as objects of a possible metaphysics, are once and for all removed from the domain of theoretical reason, which can pronounce neither for nor against them. The final result of Kantian criticism, which began from an inaccurate and artificial formulation of the problem, is thus expressed in a radical relativism, whose sole objectivity is the value universally valid for every human experience; and in a metaphysical agnosticism, which, however, in reality establishes itself within Kantian criticism itself, which is, in its own way, a metaphysics of knowledge.
Post-Kantian c. assumes manifold forms and directions, according to the principles and methods governing the solution of the problem of knowledge, and the various philosophical systematizations that arose from the trunk of Kantian criticism. Alongside idealism in its various expressions, which may properly be regarded as a form of absolute c. because of the totalitarian role assumed therein by criticism, transformed into the logic or metaphysics of the transcendental Subject, neo-c. inclines toward psychologism in G. F. Fries and F. E. Benecke; assumes a physiological tendency in Lange, the founder of German neo-Kantianism, and in Helmholtz; a metaphysical one in O. Liebmann, a realist one in L. Riehl, an empiricist one in R. Avenarius, and a logistic one in H. Cohen; develops into the theory of values with G. Windelband and E. Rickert; and finally becomes more pronounced in resolute voluntarism with C. Renouvier, who attempts, through the free act of faith, to overcome the phenomenal subjectivism of theoretical reason, which remains almost the common inheritance transmitted to c. by Kant. Recently in Italy neo-c. has been developed, besides in the ontologism of P. Carabellese, by F. Masci and, in relation to pedagogical problems, by M. Maresca. V. CONOSCENZA; KANT.