- The Soul and Rational Psychology
One historically predominant metaphysical interest has to do with identifying the nature and the constitution of the soul. Partly for practical reasons, partly for theoretical explanation, reason lodges on the idea of a metaphysically simple being, the soul. Such an idea is motivated by reason’s demand for the unconditioned. Kant puts this point in a number of ways, suggesting that the idea of the soul is one to which we are led necessarily insofar as we are constrained by reason to seek the “totality” of the “synthesis of conditions of a thought in general” (A397), or insofar as we seek to represent “the unconditioned unity” of “subjective conditions of representations in general” (A406/B433). More straightforwardly, Kant states that a metaphysics of the soul is generated by the demand for the “absolute (unconditioned) unity of the thinking subject itself” (A334/B391). The branch of metaphysics devoted to this topic is Rational Psychology. Rational psychologists, among whom Descartes or Leibniz would serve as popular historical examples, seek to demonstrate, for example, the substantiality, simplicity, and personal identity of the soul. Each such inference, however, involves concluding “from the transcendental concept of the subject, which contains nothing manifold, the absolute unity of this subject itself, of which I possess no concept whatsoever” (A340/B398). In other words, Kant takes the rational psychologist to slide (mistakenly) from formal features of subjectivity to material or substantive metaphysical claims about an alleged (super-sensible) object (the soul).
An essential aspect of all these arguments is, according to Kant, their attempt to derive conclusions about the nature and constitution of the “soul” a priori, simply from an analysis of the activity of thinking. A classic example of such an attempt is provided by Descartes, who deduced the substantiality of the self from the proposition (or, perhaps better, the activity) “I think.” This move is apparent in the Cartesian inference from “I think” to the claim that the “I” is therefore “a thing” that thinks. For Descartes, this move is unproblematic: thought is an attribute, and thus presupposes a substance in which it inheres. Kant emphasizes the a priori basis for the metaphysical doctrine of the soul by claiming that in rational psychology, the “I think” is supposed to provide the “sole text” (A343–4/B401–02). It is this feature of the discipline that serves to distinguish it from any empirical doctrine of the self (any empirical psychology), and which secures its status as a “metaphysics” that purports to provide synthetic a priori knowledge.
Kant’s criticisms of rational psychology draw on a number of distinct sources, one of which is the Kantian doctrine of apperception. Kant denies that the metaphysician is entitled to his substantive conclusions on the grounds that the activity of self-consciousness (transcendental apperception, often formulated in terms of the necessary possibility of attaching the “I think” to all my representations (B132)) does not yield any object for thought. Nevertheless, reason is guided by its projecting and objectifying propensities. In accordance with these, self-consciousness is “hypostatized,” or objectified. Here again, Kant claims that a “natural illusion” compels us to take the apperceived unity of consciousness as an intuition of an object (A402). The ineliminably subjective nature of self-consciousness, and the elusiveness of the “I” in the context of that activity, are thus the well known bases for Kant’s response to rational psychology, and the doctrine of apperception plays an important role in Kant’s rejection. For in each case, Kant thinks that a feature of self-consciousness (the essentially subjectival, unitary and identical nature of the “I” of apperception) gets transmuted into a metaphysics of a self (as an object) that is ostensibly “known” through reason alone to be substantial, simple, identical, etc. This slide from the “I” of apperception to the constitution of an object (the soul) has received considerable attention in the secondary literature, and has fueled a great deal of attention to the Kantian theory of mind and mental activity.
The claim that the ‘I’ of apperception yields no object of knowledge (for it is not itself an object, but only the “vehicle” for any representation of objectivity as such) is fundamental to Kant’s critique of rational psychology. Kant thus spends a considerable amount of time in the sections on the paralogisms noting repeatedly that no object is given in transcendental self-consciousness, and thus that the rational psychologist’s efforts to discern features of the self, construed as a metaphysical entity, through reason alone are without merit. To elucidate the ways in which the rational psychologist is nevertheless seduced into making this slide from formal representations of self consciousness to a metaphysics of the self, Kant examines each of the psychological arguments, maintaining that all such arguments about the soul are dialectical. He refers to the arguments designed to draw such conclusions, “transcendental paralogisms.” A transcendental paralogism, according to Kant, is a “syllogism in which one is constrained, by a transcendental ground, to draw a formally invalid conclusion” (A341/B399). Kant’s subsequent efforts are thus directed towards demonstrating the paralogistic (fallacious) nature of the arguments about the soul.
Kant’s diagnosis of the fallacies that characterize these arguments has received considerable attention, and has generated considerable controversy. In each case, Kant tells us, the argument is guilty of the fallacy of sophisma figurae dictionis, or the fallacy of equivocation/ambiguous middle. Kant suggests that in each of the syllogisms, a term is used in different senses in the major and minor premises. Consider the first paralogism, the argument that allegedly deduces the substantiality of the soul. In the A edition, Kant formulates the argument as follows:
That the representation of which is the absolute subject of our judgments and cannot be employed as determination of any other thing, is substance.
I, as thinking being, am the absolute subject of all my possible judgments and this representation of myself cannot be employed as determination of any other thing.
Therefore, I, as thinking being (soul), am substance. (A349)
Kant locates the equivocation contained in the argument in the use of the term “substance.” According to Kant, the major premise uses this term “transcendentally” whereas the minor premise and conclusion use the same term “empirically.” (A403). What Kant appears to mean is this: the major premise deploys the term “substance” in a very general way, one which abstracts from the conditions of our sensible intuition (space and time). As such, the major premise simply offers the most general definition of substance, and thus expresses the most general rule in accordance with which objects might be able to be thought as substances. Nevertheless, in order to apply the concept of substance in such a way as to determine an object, the category would have to be used empirically. Unfortunately, such an empirical use is precluded by the fact that the alleged object to which it is being applied is not empirical. Even more problematically, on Kant’s view, there is no object given at all. In Kantian jargon, the category only yields knowledge of objects if it is “schematized,” applied to given objects under the conditions of time.
This same kind of complaint is lodged against each of the paralogistic syllogisms that characterize Rational Psychology. Thus, Kant argues against the inference to the simplicity of the soul, by remarking that the psychologist here is surreptitiously deducing the actual simplicity of a metaphysical object simply from the formal features of subjectivity (the fact that the “I” is unitary in our representational economy). The personal identity of the soul is attacked on similar grounds. In each case the metaphysical conclusion is said to be drawn only by an equivocation in the use or meaning of a concept of the understanding.
This illustrates Kant’s efforts to demonstrate the fallacious nature of the arguments that characterize metaphysics, as well as his interest in identifying the sources of such errors. Given this, Kant’s criticisms of rational psychology are not as straightforward as one might expect, for embedded in his criticisms of rational psychology are actually a number of distinct charges: 1) The idea of the soul, although it is one to which we are naturally led in our quest for the unconditioned ground of thought, does not correspond to any object that is (or could be) actually given to us in intuition. The hypostatization of this idea, therefore, although it may be natural, is deeply problematic. 2) Because the idea of the soul does not yield, by itself alone, any knowable object, the arguments about it, although they may have the appearance of being legitimate, in fact involve dialectical applications of concepts. The arguments, in other words, involve fallacies that vitiate their conclusions. 3) The arguments are traceable back to certain features of human reason that may not be eradicated, but that can and ought to be curbed and critically reinterpreted. More specifically, the demand for the unconditioned, and the idea of the soul to which it gives rise, may be construed regulatively as devices for guiding inquiries, but never constitutively — never, that is, as yielding grounds for any a priori synthetic knowledge of a metaphysical self given immediately to pure reason.
Kant’s Paralogisms have received considerable and focused attention in the secondary literature. See Ameriks (1992), Brook (1994), Kitcher, Patricia (1990), Powell (1990), Sellars (1969, 1971), Wolff, R. P. (1963). There are also excellent discussions to be found in Allison (1983, 2004), Bennett (1974), Buroker (2006), Guyer (1987), Wuerth (2010), Bird (2006).