Department of Philosophy
Faculty of Arts
The role of the Metaphysical Deduction in Kant's Critique of Pure Reason is to show the number and identity of the pure concepts of the understanding. Kant arrives at this conclusion by means of a reflection on the forms of logical judgments, which are argued to correspond in some way to the pure concepts of the understanding.
How is the relation between the logical forms and the pure concepts of understanding possible? In other words, how is it possible that purely abstract logical forms, which are in effect nothing but syntactic means by which one can classify propositions, are closely related to the categories, which are, as Kant tries to show, constitutive of the phenomenal world of science? Kant's text on this matter is known to be obscure. So I would like to propose an answer to the question above, which is that the relation between the logical forms and the categories is a two-way one. Taking a clue from the relation between freedom and moral law in Kant's practical philosophy, I would like to point out that the logical forms are the ratio cognoscendi of the categories, since they provide the key to knowing the categories. On the other hand, the categories are the ratio essendi of the logical forms, for it is the former that are the condition of the possibility of the latter. Kantian commentators usually mention the relation from the logical forms to the categories only, but they seem to ignore the essential role of transcendental and general logics, which is explicitly discussed in the passage from A50/B76 to A64/B88. The distinction will be the basis of my interpretation here.
The paper is divided into five parts. The first part discusses the distinction between the two logics. The second part will concern my argument for the two-way relation in detail. The third part of the paper concerns textual evidence in Kant of the two rationes as well as relevant passages where it can be seen that Kant regards the relation as reciprocal, each in a different way. In the fourth part, I will show how my account differs from the main trend of leading commentators on the Metaphysical Deduction that seeks to show that the logical forms and the categories are to be regarded as not different from each other in essential aspects, but only in that the categories are the logical forms that have been provided, or are considered in relation to, the "transcendental content," which they interpret as some kind of semantic content--what the pure logical forms mean or refer to. Finally, the fifth part will conclude the paper.
According to Kant, general logic is the study of derivations among the forms of proposition with the aim of preserving consistency. It is only the study of the forms of judgments, which are subtracted from any particular content. It "considers only the logical form in the relation of any knowledge; that is, it treats of the form of thought in general" (A55/B79). On the other hand, transcendental logic is concerned with what Kant calls "empirical thought of objects"--that is, thought in so far as it is affected by empirical intuitions and hence by the synthesis of the manifold of space and time.
Kant claims that transcendental logic "treat[s] only of the origin of the modes in which we know objects, in so far as that origin cannot be attributed to the objects" (A55/B80). In other words, the subject matter of transcendental logic is the search for and study of how knowledge of objects is possible--the "referring back" to the origin of the mode in which we know object. This referring back obviously does not proceed a posteriori; hence the process is analogous to the role of a priori intuitions in constituting the forms that are presupposed by an act of the mind relating immediately to singular objects. Since transcendental logic is concerned with such an a priori origin, it could not by limited only to the analytical study of pure relations between judgmental forms and of abstracting formal logical rules from such relations. In a nutshell, then, the difference between the two logics according to Kant is as follows: Formal logic treats of formal, syntactical relations between judgments with no regard for their empirical, mathematical or even transcendental, content. Its province does not include how such judgments come about in the first place. Since judgmental forms are abstractions from ordinary employments of concepts in humans' attempts to communicate and to gain knowledge of the phenomena, formal logic is not specifically concerned with the problem of how understanding is successful by means of either empirical, logical, or mathematical judgments. The investigation of the condition of possibility of such employments of concepts and of understanding--the "tracing back to the origin" of the whole process of abstraction--is the domain of transcendental logic.
According to Kant,
Such a science, which should determine the origin, the scope, and the objective validity of such knowledge, would have to be called transcendental logic, because, unlike general logic, which as to deal with both empirical and pure knowledge of reason, it concerns itself with the laws of understanding and of reason in so far as they related a priori to objects (A57/B82-83).
It is clear that transcendental logic is not a treatment of purely formal and abstract relations among propositions. Kant mentions "the origin, the scope, and the objective validity" of knowledge claims, so transcendental logic is limited to the investigation of how such knowledge claims are possible. That they are possible is taken by Kant as obvious and self-evident, as his discussions of such disciplines as geometry and science attest. The task of transcendental logic then forms the main core of the realization of Kant's overall purpose in the Critique, that of showing how synthetic judgments are possible a priori. Transcendental logic cannot be merely another species of formal, logical or conceptual investigation for the simple reason that such enterprise is exhausted by general logic. On the other hand, transcendental logic cannot be a kind of empirical investigation either; in fact, both the formal and empirical claims to knowledge, including, most importantly, the synthetic a priori, presuppose transcendental logic in the first place.
This distinction between formal and transcendental logic is the key to understanding the bridge between the table of logical forms and the corresponding table of categories. Looking back at the core text of the Metaphysical Deduction, one finds that the passage from A76/B102 to A80/B106 is very obscure, and it is not surprising to see that many diverging interpretations have been given on it.
According to most commentators, the derivation is only from the logical forms to the categories. It seems natural that the logical forms themselves are somehow the basis from which the corresponding pure concepts of the understanding are derived. Nevertheless, a close examination of the distinction between general and transcendental logic shows that the reverse is also true in a different way. Since general logic is a way according to which the subject comes to have content of knowledge, and since it is the very task of transcendental logic to investigate the origin--the source of one's unassailable right--of one's knowing, both analytically and synthetically, the latter is the more basic investigation in the sense that general logic, according to Kant, is only possible because transcendental logic is its necessary condition. Thus, the logical forms of judgments are already conditioned by the categories by means of unity effected by synthesis.
At the beginning of the section on The Clue to the Discovery of All Pure Concepts of the Understanding, Kant writes: "If we abstract from all content of a judgment, and consider only the mere form of understanding, we find that the function of thought in judgment can be bought under four heads, each of which contains three moments" (A70/B95). "All content of a judgment" here clearly refers to the total sum of content in language--all the possible sentences in a language, a total body of discourse. Since the logical forms are obtained by abstracting from such discourse, they are crucially dependent on it. The manner in which Kant and the logicians of his day arrive at the Table of Logical Forms at A70/B95 is as follows: They observe the language used in diverse situations and the logical relations of the sentential components of that language. Furthermore, they consider the total sum, the infinitely many sentences in a language which embody all possible meanings or content, which they abstract away. The result of such abstraction is then the Table given by Kant at A70/B95.
Viewed this way, then, the logical forms could be said to owe their origins to discourse. Now the distinction between formal and transcendental logic becomes crucially relevant, for the overall aim of the Critique is to find out how synthetic knowledge is possible a priori, and essential to this project is the role of transcendental logic, which seeks the ground upon which knowledge is possible. Kant tries to show such a priori ground in the Metaphysical Deduction, which can be recognized by reflecting on the logical forms themselves.
Kant argues that the categories constitute such transcendental, a priori ground for discourse. This argument will naturally have to be completed in the Transcendental Deduction; in the Metaphysical Deduction, nevertheless, Kant's purpose is only to point out the correspondence between the two tables. Since transcendental logic is the investigation of the necessary condition of possibility of logical forms, and since Kant has already spelled out the logical forms in the Table, it is natural to assume that there has to be an account of the necessary condition of possibility of the Table itself. General logic shows that there are twelve logical forms, so the task of transcendental logic is to find the condition of possibility for each of them. Kant is pointing out that, from the fact that there are two distinct kinds of investigation, one has to posit the categories which are the transcendental-logic-analogues of the logical forms obtained from within general logic.
Kant tries to show that reflections on the abstracted forms of judgments, based on the distinction already discussed in the section on Idea of the Transcendental Logic (A50/B74 - A65/B88), reveal that there has to be the pure concepts of understanding corresponding to the abstract forms. Since transcendental logic especially treats of the bound of possibility of the former, it has to have analogues for each member of the Table of Logical Forms. The Metaphysical Deduction, therefore, could be viewed as an introduction of the important players Kant's critical project. General logic is concerned with the forms of discourse in general, hence it is already constrained by the limit of possibility within which meaningful discourse can occur. Due to the fact that the Table of Logical Forms represents all the possible forms that sentential components in discourse can assume, searching for the necessary condition of the possibility of such a table is tantamount to looking for the necessary condition of the possibility of discourse in general. The focal point of this search in Kant lies in the argument from A76/B102 to A83/B109.
Transcendental logic has as material a "manifold of a priori sensibility," functioning as "material for the concepts of pure understanding" (A77-78/B102). Since transcendental logic is concerned expressly with the possibility of human knowledge, the relevance of human receptivity already treated in the Aesthetic becomes necessary. In Kant's words: "But if this manifold [i.e. of space and time, and so of empirical intuitions in general] is to be known, the spontaneity of our thought requires that they be gone through in a certain way, taken up, and connected" (A77/B102). Kant names this act "synthesis." The idea is that any act of thinking requires an act of joining together various representations in one act of Erkenntnis, or in other words in one act of mentally grasping of a distinct mental object. Representations presented by receptivity cannot be known if they have not already been "taken up" and "connected" by the mind through synthesis.
The upshot is that any act of judgment requires synthesis. According to Kant at A78/B103, "By synthesis, in its most general sense, I understand the act of putting together, and of grasping what is manifold in them in one act of knowledge" (in einer Erkenntnis). For example, when one thinks, or says out loud, "This, before me, is a cat," or "I am having a distinct image of a red triangle," she is making a judgment based on her intuitions. Such judgments are encoded in form of a language.
This point about having a judgment in a language is very important as a key to understanding how Kant bridges the distinction between the logical forms and the categories, as he states in the following passage:
The same function which gives unity to various representations in a judgment also gives unity to the mere synthesis of various representations in an intuition; and this unity, in its most general expression, we entitle the pure concepts of the understanding. The same understanding, through the same operations by which in concepts, by means of analytical unity, it produced the logical form of a judgment, also introduces a transcendental content into its representations, by means of the synthetic unity of the manifold in intuition in general. On this account we are entitled to call these representations pure concepts of the understanding, and to regard them as applying a priori to objects--a conclusion which general logic is not in a position to establish (A79/B104-105).
The question is: how can the categories be the unity by means of which the understanding produces the logical forms through analytical unity? The answer must lie in the fact that the categories are the most general forms possible for thinking, and are the a priori ground of possibility of the latter. Since we have already seen in the case of logical forms that there are twelve such forms constituting the forms of discourse in general, in thinking these twelve forms are also present, but now they act as "pure concepts of the understanding," which are necessary for the understanding to understand anything at all or to "think an object of intuition" (A80/B107). Thus, in so far as a meaningful sentence reflects thinking and understanding, it is also ultimately unified through the categories as the most general forms of thinking. In other words, since judgments are in form of a language, and since Kant tries to show that there are twelve forms that judgments can take, and since any act of thinking requires synthesis in the first place, thinking can then proceed through twelve possible channels only. These channels, obviously enough, are the categories.
For Kant, concepts are "discursive" and not "intuitive." They are integral parts of judgments, so they are based on what Kant terms "functions," which are "the unity of the act of bringing various representations under one common representation" (A68/B93). The pure concepts of the understanding are then the most general concepts possible; Kant argues that they are the ways or modes of unification that are the most basic, and that they are integral to any act of thinking whatsoever.
"The same function of understanding" gives rise to unity in intuitions as well as in judgments. This same function is then shown to be at work both in uniting representations in an intuition and in a judgment. Hence there are two levels of synthesis. The first one is the level of intuition. The subject takes up the raw sensory data and work it up, so to speak, into something that can be directly thought of as individualized representations. The second level is at the level of concepts. The synthesizing act at this level is achieved by looking for common properties among various intuitions under one general heading, thus uniting them. So the act involves application of concepts to the intuitive material already presented. Kant maintains that, in order that concepts be applicable to intuitions, synthesis is required. The act itself, however, is the same in either case, since it consists of the function of uniting and conjoining representations in either case. Therefore, it is clear that application of concepts requires synthesis from the beginning.
The whole idea might be better understood if an analogy with the Metaphysical Exposition of Space and Time at A22/B37 to A25/B40 and A30/B46 to A32/B48 is taken into consideration. In the Aesthetic space (and time) is shown to be a necessary condition for the possibility of perceiving something as outside the subject. In this present case, the target is to find such a condition for discourse. Kant thinks that sentences comprising discourse can be grouped into twelve most basic forms. These forms, however, are not such a condition of possibility of discourse because they are obtained analytically by abstraction from all content of judgments (or statements) in discourse. What he is looking for, on the other hand, is something without which discourse would not be possible. The search naturally traces to individual acts of thinking and uses of language. These uses would not be possible without occurring through one or more of the twelve possible channels; these channels are, therefore, such a condition of possibility. Since such uniting is always accomplished through twelve possible channels, the categories are the conditions of possibility for the logical forms, which are abstracted from discourse.
To sum up the argument: Any judgment requires synthesis. Consequently, since there are twelve most general forms that a judgment can take (as twelve ways or modes of unification), there are also twelve corresponding forms of thinking. The reason is that discourse in general is made possible by acts of thinking in the first place, or in other words, discourse is only "thinking out loud." There being discourse presupposes that there is a community of conversing beings. Success in communication in turn presupposes that these beings possess some ability a priori to communicate. This ability is embodied in rational beings in the form of an ability to unite representations according to the twelve categories as the twelve possible channels of uniting representations into complete thought.
In other words, sentences in Mentalese, or in a language of thought, are only possible because the subject is able to unite components in such language according to the twelve possible channels of unity. Sentences in Mentalese are but exact reflections of sentences uttered in public. The latter could not exist as a means of understanding if not for the sentences "already in the head." Therefore, the twelve possible channels of unity, taken as a whole, is the condition without which sentences in public language are not possible at all. On the other hand, we know that these possible channels are thus and so only when we attend to the abstraction of public language, resulting in the Table of Logical Forms. This, I submit, is the reason why the two Tables completely correspond to each other.
Consequently, an account of the correspondence between the two sets of forms can now be proposed. On the one hand, the categories are the foundation upon which discourse is possible. On the other hand, the logical forms are publicly available as a means by which the identities and number of the categories are known to us. Therefore, the relationship between the logical forms and the categories goes both ways. On the one hand, the logical forms themselves do not exist in vacuo apart from the conditions of possibility of thinking in general. On the other hand, we are able to recognize the complete Table of Categories only through the corresponding logical forms. Thus the logical forms, according to a traditional parlance, are the ratio cognoscendi of the categories, while the latter is the ratio essendi of the former. The categories, in other words, are the condition of possibility of the logical forms, and the latter is the only condition by which the former are known.
The relation between the categories and the logical forms in the Metaphysical Deduction here runs parallel to that between freedom and moral law in Kant's practical philosophy. In a note in the Preface to the Critique of Practical Reason, Kant writes:
To avoid having anyone imagine that there is an inconsistency when I say that freedom is the condition of the moral law and later assert that the moral law is the only condition under which freedom can be known, I will only remind the reader that, though freedom is certainly the ratio essendi of the moral law, the latter is the ratio cognoscendi of freedom. For had not the moral law already been distinctly thought in our reason, we would never have been justified in assuming anything like freedom, even though it is not self-contradictory. But if there were no freedom, the moral law would never have been encountered in us.
Transcendentally speaking, freedom is the condition of possibility of the moral law, since for the moral law to be actually and necessarily binding, freedom of the will--the state of being totally unconstrained by any external forces--must be presupposed. On the other hand, moral law is the sole condition by which freedom is known and recognized, for moral law is what is directly recognizable in the thought of any purely reflective rational being; it is what lies distinctly before the mind as the guiding principle of the subject's action. The subject recognizes that such moral law points to the fact that it necessarily presupposes freedom, and since freedom lies hidden from view as the ultimate transcendental condition of possibility of moral law, moral law is then the sole factor that makes it possible for freedom to become known. This point is summed up clearly by Lewis White Beck: ". . . the concept of freedom and that of a universal practical law reciprocally imply each other. We are not directly aware of freedom, but we are directly aware of the binding quality of a universal law, for we have it presented to us in consciousness of the moral law. The moral law thus leads us inevitably to assert the existence of freedom."
So we have a direct evidence that Kant was aware of the distinction between ratio essendi and ratio cognoscendi; these relations, I would like to add, are also at work in the realm of pure reason. The logical forms are what we are directly aware of, and reflection reveals that they would not be possible if not for the categories. The relation between the logical forms and the categories then closely parallels that between freedom and moral law in the second Critique.
In a Remark in the Chapter on Principles of Pure Practical Reason in the second Critique, there is an interesting passage:
But how is the consciousness of that moral law possible? We can come to know pure practical laws in the same way we know pure theoretical principles, by attending to the necessity with which reason prescribes them to us and to the elimination from them of all empirical conditions, which reason directs. The concepts of a pure will arises from the former, as the consciousness of understanding from the latter. That this is the correct organization of our concepts, and that morality first reveals the concept of freedom to us while practical reason deeply perplexes the speculative with this concept which poses the most insoluble of problems, is shown by the following considerations. First, nothing in appearances is explained by the concept of freedom, but there the mechanism of nature must be the only clue. Second, there is the antinomy of pure reason which arises when reason aspires to the unconditioned in a causal series and which involves it in inconceivabilities on both sides, since at least mechanism has a use in the explanation of appearances, while no one would dare introduce freedom into science had not the moral law and, with it, practical reason come and forced this concept upon us.
It is the same act that attends to the necessity of, and abstracts all empirical content from, both the pure theoretical and practical principles. In the case of the former, such abstraction according to Kant has to start at ordinary knowledge claims and judgments and results in the twelve most basic logical forms. The same is also the case for the abstraction of pure practical principles. By attending to the forms of discourse in general, the structure of pure understanding is revealed, which normally would not be open to examination were it not the task of the process of abstraction that Kant mentions in the text above. On the other hand, attending to the force of necessity that pure practical laws bestow upon us entitles us to realize that freedom indeed attains the status of objective reality, even though pure theoretical understanding would be forever at a loss to explain it. The antinomy of pure reason is precisely the consequence of such transgression of pure reason beyond the bound prescribed in the Transcendental Aesthetic and Analytic. Mechanism in nature, however, is the only clue available to contrast with the force of pure practical law, and consequently the recognition of freedom as objective.
In a nutshell, then, this is simply to say that the moral law is the necessary stepping stone by means of which freedom is known as the ultimate condition of possibility of moral law itself. Analogously, the recognition of the logical forms of discourse is also the sole stepping stone by which one recognizes the overall structure of pure understanding constituted by the twelve categories. The latter are the condition of possibility of any act of thinking, each of which a particular component of discourse, from which the logical forms are abstracted.
Even though Kant does not say explicitly in the First Critique that the relation of the logical forms and the categories is as what I have argued, there are passages that strongly supports my interpretation. Indeed the title of the section, "The Clue to the Discovery of All Pure Concepts of the Understanding" (A70/B95), states very much in literal terms one aspect of the interpretation presented here. Furthermore, in the passage directly after the Table of Categories at A80/B106, he comments on the nature of the table itself:
This then is the list of all original pure concepts of synthesis that the understanding contains within itself a priori. Indeed, it is because it contains these concepts that it is called pure understanding; for by them alone can it understand anything in the manifold of intuition, that is, think an object of intuition. This division is developed systematically from a common principle, namely, the faculty of judgment (which is the same as the faculty of thought). It has not arisen rhapsodically, as the result of a haphazard search after pure concepts, the complete enumeration of which, as based on induction only, could never be guaranteed. Nor could we, if this were our procedure, discover why just these concepts, and no others, have their seat in the pure understanding (A80/B106 - A81/B107).
Kant is trying to give a justification of the Table of Categories. It is clear, at least, that he maintains that the complete list of the categories could not be obtained by the process of mere gathering of pure concepts, as Kant accuses Aristotle of doing just that in the text immediately following the quoted passage above (A81/B107). There has to be a guiding principle by means of which we are justified in claiming that our list is complete and exhaustive. Kant states that such principle comes from "the faculty of judgment," which is the same as "the faculty of thought." Now at A69/B94 Kant says that all acts of understanding can be reduced to judgments, and "the understanding is the faculty of thought." What this means is that all acts of understanding take place in language, and the language of understanding can be subsumed under what he calls "higher representation, which comprises the immediate representation and various others. . . in knowing the object" (A69/B94). Continuing the process, one certainly finds, according to Kant, the most general concepts that are available to the understanding in its act of judging. Since all acts of understanding can be reduced to the faculty of judgment, the latter faculty then is the guiding principle that justifies the completeness and exhaustiveness of the list of categories.
Here one can clearly discern the parallel between the work of the faculty of judgment and the normal process of abstraction. According to Kant, abstraction reveals that there are twelve logical forms according to the Table at A70/B95. Since understanding proceeds in language, the faculty of judgment also reveals that there are such and such "pure concepts of the understanding" that are required if the understanding is to be able to understand anything or "think an object of intuition" (A80/B106). Therefore, the faculty of judgment is able to be the guiding principle in the search for the complete and exhaustive list of categories because abstraction reveals that there are such and such number of the most general logical forms comprising a complete and exhaustive list. Kant maintains that the understanding is the faculty of thought (A69/B94), and that thought is always in language, as we have seen. The upshot is then the most general forms of language, being the results of normal act of abstraction, point a way to a realization that each of them completely corresponds to its respective forms of understanding, which constitute the faculty of judgment. Since the most general forms of language, or the logical forms, owe their origin from the mere process of abstraction, they cannot themselves be such constitutive factor. The faculty of judgment must then be constituted by another completely different set of forms or concepts--i.e. the categories, since they are the forms that constitute the justifying, transcendental origin of language itself.
This account of the Metaphysical Deduction differs from those put forth by some commentators, notable among whom is Henry Allison, who argue that the logical forms and the categories differ only with respect to the latter's being none other than the former's having been supplied "transcendental content," which they argue to be some kind of semantic content for the logical forms. In Kant's Transcendental Idealism, Allison argues that the difference between the logical forms and their corresponding categories is that the latter are provided "transcendental content" while the former do not, but in other respects they are one and the same. According to Allison, "transcendental content" is the same as the synthetic unity of the manifold, which involves a relation to objective reality. The logical forms, on this account, do not involve such objective content, but are merely forms that the understanding takes in judging. The forms are the categories when considered apart from their transcendental content.
However, I am suspicious whether Allison's account fully captures the whole issue. What I think is missed in his account is that the transcendental content is clearly related to the distinction between transcendental and formal logic, and consequently the matter of providing the necessary ground for the possibility of discourse has to be taken into consideration. The categories are indeed related to objective reality; in fact this will be the conclusion of the Transcendental Deduction, but Allison does not appear to pay attention to the fact that it is the role of transcendental logic that provides such a priori ground, which is constituted by the categories as the pure necessary concepts of the understanding. The point is: The categories are the a priori ground which makes the act of the understanding in uniting representations in judgments, whether related to objective reality or totally in imagination, possible in the first place.
This a priori ground of the necessary condition of possibility of discourse, then, is rather the "transcendental content" supplied to the logical forms. The act of synthesis functions according to one or more of the twelve categories; it is this act that supplies the transcendental content to the abstract logical forms. The supplying of transcendental content is thus nothing other than a consideration of the logical forms in relation to their necessary condition of possibility. The categories are the ultimate functions of unity which is required in each and every act of thinking; the logical forms are merely the products of the act of abstraction. Kant calls both the act of transcendental synthesis and of abstraction into logical forms "the same function" of unity (A79/B104). It is the same operation, only accomplished at different levels, as we have seen. This, however, should not lead one into concluding that the categories and the logical forms are essentially one and the same. The reason is that, in Kant's words, "the same understanding, through the same operation by which in concepts, by means of analytical unity, produced the logical forms of a judgment," and it is also the same understanding that "introduces a transcendental content into its representations" A79/B105). The act of understanding, I have argued, produces the logical forms by means of abstraction, and it also considers these forms as to their condition of possibility, which is Kant's method of transcendental philosophy. Therefore, the categories and the logical forms indeed operate on different levels; the one presupposes the other.
According to the standard view, the role of transcendental logic is specifically to supply the "content" to the judgment forms, thus making them corresponding categories. Here Schwyzer is also typical. To him the role of general logic is only horizontal, namely that it ranges over the coherence making function of the understanding, but the role of transcendental logic is to supply this with the vertical dimension which considers this function in relation to objects in general. Thus Schwyzer's view is, in short, "A given category is the corresponding logical function, conceived now as ranging over whatever might be presented as objects of thought."
This view, however, does not seem to do justice to Kant's own claim that transcendental logic is to provide the justifying origin for the claims of general logic, as we have seen. Categories represent the complete structure of thought and understanding in rational, discursive being. As such it is already presupposed in general or formal logic, which we have seen to be merely the result of abstraction according to the principle of analytical unity. The standard view seems to put the cart before the horse, so to speak. If the role of transcendental logic is merely to be the supplier of content, then it becomes unduly restricted and even has a more limited scope than its counterpart. But since transcendental logic is more fundamental, this cannot be the case.
The account I am proposing is in accordance with Kant's idea on the transcendental he espouses at A11-12/B25: "I entitle transcendental all knowledge which is occupied not so much with objects as with the mode of our knowledge of objects insofar as this mode of knowledge is to be possible a priori." The "transcendental content" is then the transcendental origin, the condition of possibility, of our modes of knowing. It is what is responsible as the a priori ground of knowing and understanding. The act of supplying transcendental content is thus the consideration of the logical forms in accordance with such origin. This origin, as Hatfield says, is neither analytic nor synthetic, but sui generis.24 The act of tracing back to the origin is accomplished by means of the synthetic unity of the manifold. Kant apparently means that it is the same function of the understanding that unites various representations resulting in a judgment in discourse coded in form of a language, and this same function also effects thinking in general. The pure concepts governing thinking then become the a priori ground of possibility for forms in discourse. That is to say, the former is the ratio essendi of the latter. And since the logical forms are the ratio cognoscendi of the categories, the tracing back to the origin of the logical forms has to make use of the material of transcendental logic because humans cannot conceive of any other possibility of thinking other than in the context of human thinking. So any attempt to understand thinking has to take place within the context of human thinking, and this, as Kant tries to show, necessarily involves receptivity, or the synthetic unity of the manifold presented as the material of transcendental logic. It is precisely by means of this material that the tracing back to the categories from their ratio cognoscendi is possible at all.
I have tried to argue that the relation between the logical forms and the categories in Kant's Metaphysical Deduction is a two-way one. On the one hand, the logical forms are the ratio cognoscendi of the categories, for it is by means of the former that the latter are known. On the other hand, the categories are the ratio essendi of the logical forms, for the logical forms, being the products of the act of abstraction that takes away all the content of all possible judgments, owe their origin to the categories, in their capacity as the condition of thought and experience in general. The distinction between transcendental and general logic figures essentially in the relation, since the task of transcendental logic is to seek the justifying origin for the role of general logic as a source of rational knowledge. Since the structure of general logic can be given in the Table of Logical Forms, the corresponding structure is also required in transcendental logic, whose structure is constituted by the Table of Categories.
Even though Kant did not explicitly state that the relation between the categories and the logical forms is not exactly as I have tried to show in the paper, there is at least a strong philosophical evidence for it. Thus, the vexing problem of how the categories and the logical forms are related to each other, I believe, can be satisfactorily solved if the relation between them is understood according to what I have argued for in this paper.