by the intellect is given the corresponding intuition is given (and this is valid for the schema of the circle, indispensable for understanding the concept of “plate”). On the other hand, Kant continues, it is symbolic when, to a concept that only Reason can think of, to which there exists no corresponding intuition, one is provided by analogy, as would be the case, for example, if I chose to represent the monarchical state as a human body. Here certainly Kant is speaking not only of symbols in the logical-formal sense (which for him are mere “characterisms”) but also of phenomena such as metaphor or allegory. But a gap still remains between schemata and symbols (we have only to think of the platypus): there is intuition, but not yet the concept, and I cannot recognize it or define it through a metaphor.

13.6. Opus Postumum

Kant bridges this gap in his Opus Postumum, in which he again tries even harder to determine the various particular laws of physics that cannot be deduced from the categories alone. In order to ground physics, he must postulate the ether as matter that, distributed throughout cosmic space, is found in and penetrates all bodies.

External perceptions, as material for a possible experience, which lack only the form of their connection, are the effect of the moving (or driving) forces of matter. Now, to mediate the application of these motor forces to the relations that occur in experience calls for identifying empirical laws. These latter are not given a priori, they need concepts constructed by us (selbstgemachte). These are not concepts given by reason or experience but factitious concepts. They are problematic (and we recall that a problematic judgment depends on the Postulate of Empirical Thought in General, so that what is in harmony with the formal conditions of experience is possible).

Concepts of this kind must be thought as the foundation of natural inquiry. We must therefore postulate (in the case of the factitious concept of ether) an absolute whole that subsists in matter. Kant repeats on various occasions that this concept is not a hypothesis but a postulate of reason, but his suspicion of the term hypothesis has Newtonian roots. In fact, a concept (built on nothing, so to speak) that renders possible the totality of experience is an abduction, which, in order to explain certain Results, appeals to a Rule constructed ex novo.12
As Mathieu (1984) observes, apropos of Kant’s last writings, “The intellect makes experience by designing the structure according to which the driving forces of the object can act.”

The reflective judgment, more than observing (and subsequently producing schemata), produces schemata so as to observe and test. And “such doctrine goes beyond that of the first Critique for the freedom that it assigns to the intellectual designing of the object” (Mathieu 1984: 231, n. 1). It is Mathieu (1984: 21) who again observes that “even keeping unchanged the necessary structure of the categories, one can equally take a further spontaneous activity into consideration, which the intellect performs starting with categories, but without remaining stalled at them … constructing not simply what derives from them, but all that we are able to think, and without falling into contradiction.” Perhaps to arrive at such boldness Kant had needed to pass through the aesthetic reflection of the third Critique; only then “is a new schematism born—the free schematism of the imagination, without concepts—as the primary capacity to organize perceptions” (cf. Garroni 1986: 226).

With this late schematism the intellect does not construct the simple definition of a possible object, but makes the object, constructs it, and in this activity (problematic in itself) it proceeds by trial and error.

At this point the notion of trial and error becomes crucial. If the schema of empirical concepts is a construct that attempts to make the objects of nature thinkable, and if a complete synthesis of empirical concepts can never be given, because new notes of the concept can always be discovered through experience (LI, 103), then the schemata themselves can only be revisable, fallible, destined to evolve over time. If the pure concepts of the intellect were to constitute a sort of intemporal repertoire, empirical concepts can only become “historic,” or cultural, however you choose to say it.13

Kant did not, in fact, say this, but it seems hard not to say it if one takes the doctrine of schematism to its logical conclusions. Peirce, for one, saw it this way, firmly putting the entire cognitive process down to hypothetical inference. Sensations appear as interpretations of stimuli; perceptions as interpretations of sensations; judgments of perception as the interpretation of perceptions; particular and general propositions as interpretations of perceptual judgments; and scientific theories as interpretations of a series of propositions (cf. Bonfantini and Grazia 1976: 13).

Given the infinite segmentability of experience, both perceptual schemata and propositions concerning the laws of nature themselves carve out entities or relations that—to a greater or lesser degree—always remain hypothetical and subject to the possibility of fallibilism.

Naturally at this point transcendentalism too will undergo its Copernican revolution. The guarantee that our hypotheses are “right” (or at least acceptable as such until proved otherwise) will no longer be sought in the a priori of the pure intellect (though its most abstract logical forms will be retained) but rather in the consensus, historic, progressive, and temporal of the Community.14 In the face of the risk of fallibilism, the transcendental too becomes historicized, an accumulation of received interpretations, accepted after a process of discussion, selection, and repudiation.15 An unstable foundation, if you will, based on the pseudo-transcendental of the Community (an optative idea more than a sociological category); and yet it is the Consensus of the Community that today makes us incline toward the Keplerian abduction rather than that of Tycho Brahe. Naturally the Community has come up with what we call called proofs, but it is not the authority of the proofs in themselves that convinces us, or keeps us from falsifying them. Rather, it is the difficulty of calling into question one proof without overturning the entire system and the paradigm on which it is based.

This detranscendentalization of knowledge comes up again, thanks to the explicit influence of Peirce, in Dewey’s notion of the “warranted assertion” (or, as we prefer to call it today, “warranted assertibility”) and remains present in the various holistic conceptions of knowledge.

—Translated by Jacob D. Blakesley and Anthony Oldcorn

A revised version of “Il silenzio di Kant sull’ornitorinco” (Eco 1998a). The subject is treated at greater length in Eco (1997b: ch. 2).

1. For the works of Kant we will use the following abbreviations: Critique of Pure Reason (CPR/A and CPR/B, according to whether the reference is to the first or second edition), Critique of Judgment (CJ), Prolegomena (P), Logic (L), and Opus Postumum (OP). [Translator’s note: The present translation has greatly benefited from the example of Alastair McEwen’s excellent English version of Eco’s Kant and the Platypus, which, in ch. 2 “Kant, Peirce and the Platypus,” covers much of the same ground.]
2. Semiotic interests are evident in some pre-Critique writings such as paragraph 10 Kant’s inaugural dissertation, De mundi sensibilis atque intelligibilis forma et principiis (“On the Forms and Principles of the Sensible and Intelligible World”), while, in his Anthropology from a Pragmatic Point of View (http://link.springer.com/content/pdf/bfm%3A978-94-010-2018-3%2F1.pdf), we see how, in the courses taught in his later years, Kant outlined (at least as a didactic tool) a summary theory of the sign—not original, but indebted to traditional doctrines, from Sextus Empiricus to Locke and perhaps Lambert, but nevertheless showing a respectful interest in the theme of semiotics. For Kant and semiotics, see Garroni (1972, 1977).
3. Husserl (1970a: 2, 833).
4. Cf. the objections by Marconi and Vattimo (1986: xix) in their introduction to the Italian translation of Rorty (1979).
5. I owe this reflection to Ugo Volli (personal communication).
6. See Kant (1968: 221–301).
7. In P, para. 18 he also speaks of a kind of superordinate genus of empirical judgments (Empirischen Urteile), based on the perception of the senses, to which judgments of experience add the concepts originating in the pure intellect. It is not clear how these empirical judgments differ from perceptual judgments, but here perhaps (without getting into Kantian philology) we can limit the comparison to perceptual judgments and judgments of experience.
8. CPR/B: 107. Therefore, “the question is not at all resolved” (Martinetti 1946: 65) concerning the difference between judgments of perception and judgments of experience. Cassirer (1918) realized this too, although he only alludes to it in note 20 of chapter II, 2: “it must be noted that a similar exposition of empirical knowledge … is not so much the description of a real objective fact, as much as the construction of a borderline case.… For Kant, no ‘singular judgment’ is given that does not already claim some form of ‘universality.’ No ‘empirical’ proposition exists that does not include in itself something asserted ‘a priori’: since the very form of the judgment already contains this claim to ‘universal objective validity.’ ” Why such an important statement only in a footnote? Because Cassirer knows that he is extrapolating according to good sense and systematic coherence what Kant should have said plainly, in order to exclude any other ambiguous formulation.
9. Here we will leave undecided whether he has perceived the stones, but has repressed this perception, so to speak, or whether he perceives only when he responds, interpreting memories of still unconnected visual sensations.
10. See, on this issue, Garroni (1968: 123; 1986, III, 2, 2) and also De Mauro (1965: 2, 4).
11. On the other hand, let us put ourselves in the shoes of a hypothetical Adam who sees a cat for the first time, without ever having seen any other