Kant certainly did not think it possible to repropound the Scholastic solution; on the contrary, if there is a genuinely Copernican aspect to his revolution, it lies in the fact that he suspends all judgment on form in re and assigns a synthetic-productive, and not merely abstractive, function to the old active intellect. As for the British Empiricists, Kant’s goal was to establish a transcendental foundation for the process that they basically accepted as a reasonable way of moving in the world, a process whose legitimacy was confirmed by the fact that, all things considered, it worked.
But in doing this, Kant considerably shifted the focus of interest within a theory of knowledge. It is rash to say, as Heidegger did, that the Critique of Pure Reason has nothing to do with a theory of knowledge but is, rather, ontology questioning itself regarding its own intrinsic possibility; but it is also true that, to use Heidegger’s words again, it has little to do with a theory of ontic knowledge, that is, of experience (1973: 24).
Yet Kant believed in the evidence of phenomena; he believed that our sensible intuitions came from somewhere; he took the trouble to articulate a confutation of idealism. Apparently it was Hume who awoke him from his dogmatic slumbers, by posing the problem of the causal relation between things, and not Locke, who had also tabled the problem of an activity of the intellect in the naming of things.
To say why, after having received an impression of something, I decide I am confronted with a tree or a stone was a fundamental problem for the Empiricists, but it seems that it became a secondary problem for Kant, overly concerned with guaranteeing our knowledge of celestial mechanics.
The first Critique constitutes not so much a theory of everyday knowledge as a theory of scientific knowledge. Kant was not interested in knowledge of but knowledge that; in other words, interested not in the conditions of knowledge (and therefore of naming) of objects as much as in the possibility of founding the truth of our propositions about objects.7 His primary interest is how it is possible to have a pure mathematics and a pure physics, or how it is possible to make mathematics and physics two theoretical bodies of knowledge that must determine their objects a priori.
The nucleus of the first Critique concerns the search for a warrant for a legislation of the intellect regarding those propositions that have their model in the Newtonian laws—and that out of necessity are sometimes exemplified by more understandable and venerable propositions such as All bodies have weight. Kant is concerned with guaranteeing the knowledge of those laws that underpin nature understood as the set of the objects of experience; he never doubts that these objects of experience are also the same objects that exercised the Empiricists so much: dogs, horses, stones, trees, or houses. But (at least until the Critique of Judgment) he seems extraordinarily uninterested in clarifying how we know the objects of everyday experience, at least those objects that today we customarily call natural kinds, such as camel, beech, and coleopteran. This was realized with evident disappointment by a philosopher interested in knowledge of, like Husserl.8 But the disappointment was converted into satisfaction for those who instead maintained that the problem of knowledge (both of and that) could be resolved only in linguistic terms, that is to say, in terms of coherency among propositions.
Rorty (1979: 3.3) takes issue with the idea that knowledge must be «a mirror of nature,» and he even wonders how it was possible for Kant to assert that intuition offers us the manifold, when this manifold is known only after it has already been unified in the synthesis of the intellect. In this sense Kant would have made a step forward with respect to the epistemological tradition that runs from Aristotle to Locke, a tradition for which attempts were made to model knowledge on perception. Kant would have liquidated the problem of perception by stating that knowledge hinges on propositions and not objects. Rorty is satisfied for evident reasons: even though his idea is to overturn the very paradigm of analytic philosophy, this is nonetheless his point of departure, even in terms of his personal history, and therefore Kant strikes him as the first to have suggested to the analytic tradition that it was necessary not so much to wonder what a dog is as to wonder if the proposition Dogs are animals is true or not.
This does not eliminate Rorty’s problems, not even if he intended to reduce knowledge to a purely linguistic problem, because it prevents him from tackling the problem of the relations among perception, language, and knowledge. That is to say, if the opposition is (if, like Rorty, we may pick up the thread of an opposition proposed by Sellars) between «knowing how X is» and «knowing what type of thing X is,» we would still have to ask ourselves whether in order to answer the second question it is not necessary also to have answered the first.9
This does even less to eliminate the problems of Kant, who not only seems uninterested in explaining how it happens that we understand how X is but also is unable to explain how we decide what type of thing X is. In other words, the first Critique fails to deal with the problem of how we understand that a dog is a dog, and it does not even explain how we are able to say that a dog is a mammal. There is nothing extraordinary about this if we reflect upon the cultural climate in which Kant was writing.
By way of examples of rigorous knowledge that might be founded a priori, he had at his disposal mathematical science and physical science as they had already been established for centuries, and he knew very well how to define weight, extension, force, mass, triangle, or circle. But he did not have a science of dogs, just as he did not have a science of beech or lime trees, or of coleopterans. Let us not forget that when he was writing the first Critique, only a little more than twenty years had passed since the publication of Linnaeus’s Systema Naturae, the first tentative monument to the establishment of a classification of «nat ural kinds.»
The dictionaries of the preceding century defined dog as a «known animal»; attempts at universal classification such as those of Dalgarno or Wilkins (seventeenth century) employed taxonomies that today we would define as approximative. 10 One understands why Kant could define the concept of dog as an empirical one; and, as he was to repeat on several occasions, we shall never be able to know all the notes of empirical concepts. That is why the first Critique begins (Introduction vii) with the declaration that in transcendental philosophy concepts containing anything empirical must not appear: the object of the a priori synthesis cannot be the nature of things, which is in itself «inexhaustible.»
Therefore, even if he realized that he was reducing knowledge to the knowledge of propositions (and therefore to linguistic knowledge), Kant could not have posed himself the problem, which Peirce was to set himself, that the nature of knowledge was not linguistic but semiosic. It is true that, while Kant could not do this in the first Critique, he was to move in this direction in the third, but in order to take that path he had to reckon with the difficulties encountered in the first Critique by bringing into play the notion of the schema, of which more will be said in 2.5.
According to a Kantian example (P §23),11 I can move from an uncoordinated succession of phenomena (there is a stone, it is struck by the sun’s rays, it is hot—and, as we shall see, this is an example of perceptual judgment) to the proposition The sun heats the stone. If we suppose that the sun is A, the stone B, and the being hot C, we can say that A is the cause whereby B is C.
According to the table of categories, of transcendental schemata and of the principles of pure intellect (see fig. 2.1) the axioms of intuition tell me that all intuitions are extensive quantities and, through the schema of the number, I apply the category of the singularity to A and B; through the anticipations of perception, by applying the Schema of Degree, I state the reality (in an existential sense, Realität) of the phenomenon given me by intuition. Through the analogies with experience, I see A and B as substances, permanent in time, into which I insert accidents; and I establish that the
Figure 2.1 Table of categories
accident C of B is caused by A. Finally I decide that what is linked to the material conditions of experience is real (reality in the modal sense, Wirklichkeit) and, for the schema of existence in a set time, I assert that the phenomenon is effectively occurring. Equally, if the proposition were By natural law it always and of necessity occurs that the sun’s light heats (all) stones,
