Just the other day SelfAwarePatterns published an excellent entry on the overuse of the phrase “illusion” in explaining away phenomena, and as I agree with the dangers of hasty reductionism, I chimed in with a Kantian-inspired comment on the objective reality of “the ways things appear” being guaranteed by a necessary connection to “the ways things are in themselves”. Following that encounter I recalled how much Kant would disagree with my statement, but at the same time, how necessary something like this position is to making Kant’s view work. This is one of the main criticism’s of Kant’s epistemological theory of Transcendental Idealism, and today I want to consider if such a criticism can be weathered.
1. Kant’s Transcendental Idealism and the Distinction Between Noumena and Phenomena
In the Transcendental Aesthetic Kant argued that space and time are added to what is perceived by the understanding, such that, there is a really existing thing that is being perceived, but how it appears to the subject is structured by the understanding. But if this is the case, then what we have access to in our minds is different than the real objects of the world, though they do exist. Kant terms the appearances of objects that we have access to from sensible intuitions, ‘phenomena’, and those things that we do not have access to from sensible intuitions, ‘noumena’. While phenomena are the way objects appear through the effects of the sensibility, noumena are the way objects are without being shaped by the sensibility. Noumena are, then, the objects as they really are, and what Kant calls a thing-in-itself. Kant points out that if sensible intuitions give us phenomena, then another faculty of intuition must exist to give us knowledge of noumena. This leads Kant to posit that as noumena can only be known by intellectual intuitions, noumena are intelligible entities impossible of being known by the sensibility.
Kant posits that we cannot have objective knowledge of noumena precisely because noumena are not given by sensible intuitions. In the Transcendental Deduction, Kant found that the experience of objects depends on the transcendental synthesis of imagination to unify manifolds of intuition into one sensible object, and that this synthesis is made possible by the categories reveals that the categories make experience possible.
In the schematism Kant endeavors to explain how the categories in fact apply to appearances. We must spend some time tending to this issue as it is crucial to Kant’s conclusion that we cannot have knowledge about noumena. Kant posits that there must be a transcendental schema that connects the pure concept to the appearance. A transcendental determination of time is homogenous with the categories because time is necessary for a manifold of intuitions to be unified by a category. Moreover, the transcendental determination of time is homogenous with appearance because time is added to all appearances by the understanding. As time is therefore homogenous with both the categories and appearances, the transcendental determination of time must be the transcendental schema that makes possible the application of the pure concepts to appearances. In other words, the schemata are the temporization of the categories so that they are homogenous with appearances.
That the categories must be temporalized through the schemata in order to apply to appearances is of great importance, as the consequence is that the categories only have use when applied to what is given through the sensibility. Kant notes this in positing, “the schemata of the pure concepts of understanding are thus the true and sole conditions under which these concepts obtain relation to objects and so possess significance. In the end, therefore, the categories have no other possible employment than the empirical” (Critique of Pure Reason, 186). If it not the case that the categories have any use when not in relation to sensible intuitions, and noumena are not known from sensible intuitions, then the categories cannot be used to make claims about noumena.
However, the categories are what make objectivity possible, such that, if the categories cannot be applied to noumena, then there can be no objective truths about noumena. On the connection between the categories and objectivity, Kant argues that objective scientific and mathematical knowledge is possible in virtue of the synthetic principles of understanding, which are the result of the schematized categories. The synthetic principles of pure understanding are divided into two categories, the mathematical, which are necessary for experience, and the dynamical, which emerge upon reflection on experience. Observations that fit with these principles have objective validity because they are synthetic a priori truths derived from the a priority of the categories, which are universal in human experience. On this Kant writes, “the table of categories is quite naturally our guide in the construction of the table of principles. For the latter are simply rules for the objective employment of the former” (Critique of Pure Reason, 196). The synthetic principles of pure understanding, then, allow humans to have objective scientific knowledge by allowing that the various intuitions of a thing can rightly be brought together in one appearance (axioms of intuition), and that changes in what is sensed about this appearance can be measured in degrees (anticipations of perception). Together, the synthetic principles of mathematical employment just discussed enable scientific inquiry with objective answers. Therefore, the categories cannot be applied to noumena because the categories only have meaning when temporalized to fit with sensible intuitions. Kant’s argument for this is that, “the principles of pure understanding are only of empirical, never of transcendental employment, [so] that outside the field of possible experience there can be no synthetic a priori principles” (Critique of Pure Reason, 265). Thus, as it is impossible to apply the synthetic principles of understanding to noumena, and the synthetic principles of understanding are what make synthetically derived objective knowledge possible, objective knowledge cannot be derived about noumena, and so we cannot even speak about noumena other than to say that they must exist.
Thus, Kant’s transcendental idealism requires that there are entities existing outside of the mind so that there may be something given to the mind through the sensibility, and that the sensibility shapes the entities so that what is given to the mind is the appearance of an object, and not the thing-in-itself. The benefit of Kant’s system is that we can have objective scientific and mathematical knowledge about the way things appear to us because the understanding and the sensibility in conjunction shape appearances, a universal feature of human experience. The drawback is that we cannot know or speak about noumena.
2. The Standard Objection to Positing the Existence of Noumena
In line with the criticism of other commentators, A.C. Ewing argues that Kant’s Transcendental Idealism is problematic because in order to establish a distinction between noumena and phenomena, categories must be attributed to noumena. Moreover, in order for there to be this distinction, it seems that noumena must cause the sense data that we then shape into appearances. On the issue of applying categories to things in themselves, Ewing writes that,
This is not an adventitious slip but necessary to his philosophy. For (1) things-in-themselves must be subject at least to the category of “reality”; [and] (2) we cannot even think of physical objects as appearances of things-in-themselves without thinking of them as determined by the latter, which involves the category of causality, and it is clear that Kant’s whole conception of appearances presupposes the action on us of a thing-in-itself as a part cause of our representations accounting for the empirical element in knowledge (A Short Commentary on Kant’s Critique of Pure Reason, 187-188).
This criticism is quite serious for Kant’s Transcendental Idealism. We have seen that Kant posits that the categories only have meaning when applied to empirical experience, and as noumena are not known from empirical experience, it follows that we cannot speak of noumena even to suggest that they exist, because such talk is meaningless. Yet if this is the case then the distinction between noumena and phenomena crumbles. As this distinction is necessary for the possibility of objective knowledge about how things appear to us, without the division of noumena and phenomena we are thrown back into skepticism about objective knowledge. Thus, we should be motivated to find a way to posit the distinction between noumena and phenomena without applying categories to noumena.
3. Robert Adams’ Solution to The Standard Objection
Robert Adams argues that Transcendental Idealism avoids the problem of applying the categories of ‘reality’ and ‘causality’ if noumena are taken to be what Kant calls ‘problematic concepts’. Kant writes that a problematic concept is a concept wherein, “the objective reality of a concept cannot be in any way known, while yet the concept contains no contradiction” (Critique of Pure Reason, 271). Taking noumena as a problematic concept in no way stretches Kant’s position, as Kant himself posits that ‘noumena’ is a problematic concept because it is not contradictory. If Adams can show that the objections to Kant’s positing of noumena arise because they ignore the fact that noumena are problematic concepts, then it seems that the standard objection is avoided.
Adams posits that Kant’s use of problematic concepts is to establish a distinction between real possibility and logical possibility. A concept has real possibility if it can relate to an object and have meaning. In order to be logically possible, a concept need only be non-contradictory; it need not be possible to apply that concept to an object. Problematic concepts, then, are concepts that are known to be logically possible, but could be either really possible or not really possible. Adams elucidates the definition of a problematic concept by writing that for a problematic concept, “we do not know that an object for the concept is not possible. Indeed it is only the real possibility of such an object that is unknown to us. We do know that it is logically possible, inasmuch as there is no contradiction in the concept” (“Things in Themselves”, 816). Thus, problematic concepts are non-contradictory concepts that either do or do not correctly relate to an object.
Understanding noumena as problematic concepts enables Transcendental Idealism to avoid attributing categories to noumena because logical possibility does not require that noumena are real, such that, noumena are not subject to the category ‘reality’. To claim that noumena must be really possible in order to hold the distinction between noumena and phenomena requires attributing the category of ‘reality’ to noumena. But as Adams has shown that noumena can be considered as logically possible without passing judgment on their real possibility, it follows that we can have the concept of noumena without attributing ‘reality’ to noumena.
Against the second part of the standard objection – that the category of ‘causality’ must be attributed to noumena – Adams responds that, “the concept of noumenal causality should be viewed as a Kantian problematic concept” (“Things in Themselves”, 820). Doing so entails that noumenal causality is logically possible, but that it is unknown whether noumenal causality has real possibility. In other words, by understanding noumenal causality as a problematic concept, it need not be the case that the categories be applied to make a judgment on the possibility of noumenal causality, because the categories are only needed to judge the real possibility of a concept, not the logical possibility of a concept. Thus, understanding problematic concepts as making a distinction between real and logical possibility allows for the postulation of noumena without necessarily applying categories to them.
If Adams’ understanding of ‘problematic concept’ is correct then Kant’s theory does not attribute categories to noumena, and thus, Kant’s theory is not inconsistent after all. As it seems that Adam’s conceptualization of ‘problematic concept’ is a fair reading of Kant’s work, it seems that this is the correct way to respond to the standard objection. That the postulation of noumena is only a postulation of the logical possibility of noumena allows the distinction between noumena and phenomena to stay in place, and thereby enables the possibility of objective knowledge of phenomena.