Kant’s Fourth Paralogism, On Idealism

Contents:

• Introduction
  • The Problem of the External World
  • “Reality”
  • Realists and Idealists
• Part 1
  • The Cartesian Predicament
  • A dilemma
  • An Objection to Idealism
  • A Reply
• Part 2
  • 2.1 The Transcendental Object
  • 2.2 Strategic Agnosticism

Introduction

Kant’s fourth Paralogism takes as its theme the justification of transcendental idealism against other approaches to what has been called “the problem of the external world.“ This problem came down to Kant largely due to the influence of Descartes, for whom the justification of the reality of the every day world of objects in space and time became a philosophical problem. It might be framed as follows:

PEW: Can the reality of the world of our everyday experience be justified and, if so, then how?

The sense in which “reality“ is understood will necessarily play an important role in answering this question. In one sense, it may be taken as connoting existence (or actuality) especially with respect to our perception of the world. Thus, one might say that in one way, a question about the reality of an apple in my perception concerns whether it exists or not. This brings up the question of how the existence of any such object is to be justified. The possibility that the world we take ourselves to exist in is merely an illusion or at any moment might be considered a dream (à la Descartes) is something most philosophers who have approached the problem would like to avoid.

In a second sense, “reality“ concerns the ontological status of objects in our experience. For example, one might question whether the reality of perceptible objects merely phenomenal. If so, do they exist independently of us as material, self-subsisting substances or should they be considered mind-dependent entities? In this sense, the reality of an object refers to the kind of being it is.

A third sense relates to the veridicality of our perceptions. This sense of “reality” involves our capacity to distinguish “true” from “false” perceptions. For example, someone might say, “This is a real apple“ as a way of distinguishing it from a false apple. In this case, the real apple is ultimately he one that corresponds to our concept (whether explicit or implicit in our identification practices) of what an apple is. From the standpoint of scientific reasoning and in many cases where custom and habit do the work of identification, an apple is a “true” apple if and only if it has such features.

Much of the work of classical Aristotelian philosophy might be seen as an attempt to work out the features of an object that would serve to distinguish it from all other false cases of that object, as a way of bridging the gap between perceiving and knowing. In Locke’s Essay, the role language plays in such identification projects (which naturally plays an important role in any realist approach to our perceptual experience) becomes more acute.

Finally, Kant makes a direct fit between concepts and things the basis for synthetic a priori concepts. Although he does not make language use the focus of his discussion of the categories and their function in us, arguably his approach is idealistic in a platonic sense: in other words, the fit between the categories, the concepts that underlie them, and the possibility of knowledge is fixed by the categories and concepts themselves. To understand how we arrive at our capacity to know anything at all we need to “work backwards“ to discover the nature of the categories and the fundamental concepts that underlie their application. The Kantian project is in the first instance one that is fundamentally about analysis rather than invention, which may be the key to understanding why the first half of the critique is devoted to the project of unfolding a “transcendental analytic.”

But to return to our main point of discussion, existence, veridicality, and ontological questions about the ultimate nature of our perceptions themselves all enter into into the debate about the reality of the external world among realists and idealists of one kind or another. Generally speaking, while the realists took the objects we perceive to present their existence directly to us in at least some (or most) cases and to have a mind-independent, substantial existence, the idealists took the sensible world to be mediated by our perception, so that their true nature and even their existence outside our perception had to remain in doubt. Therefore, for the Idealists general skepticism and the questions it invites (Are we a brain in a vat? Are we being deceived by a Cartesian evil genius? Do we live in a simulated universe?) about the reality of our perceptions are bracketed in favor of an approach that acknowledges the reality of the appearances of things to be our only means of understanding them.

Perhaps Newton is the only prominent thinker among the early moderns who takes a truly realist view of the physical world. Berkeley, by contrast, is the purest example of an idealist prior to Kant. Locke has what Kant labels a “dualistic“ view, according to which our perceptions of secondary qualities (color, taste, sound, and texture) may be considered to be realized only within our own mind, while the primary qualities (shape, solidity, extension, and number) are considered to belong to things in themselves, to their independent reality, which is fully realized independently of our perception.

In what follows, we will take a look at the nature of the debate between realists and idealists as it enters into the context of the fourth paralogism and then try to get a clear idea about how Kant responds to it. It will be seen that The debate between realists and idealists presents a fundamental dilemma both to Kant and to us as philosophical thinkers.

1.

Let’s begin with Kant’s initial description of the Cartesian predicament which unfolds in the argument that begins the section:

That, the [1.] existence of which can only be inferred as a cause of given perceptions, has a merely doubtful existence.

Now [2.] all outer appearances are of such a nature that their existence is not immediately perceived, and that we can only infer them as the cause of given perceptions.

Therefore [3.] the existence of all objects of the outer senses is doubtful. This uncertainty I entitle [4.] the ideality of outer appearances, and the doctrine of this ideality is called idealism, as distinguished from [5.] the counter-assertion a possible certainty in regard to objects of outer sense, which is called dualism.”

A366-367 (Numbers in brackets have been added, emphasis in italics is as in the text.)

The particularly Cartesian nature of the argument is brought out in the interpretive lines that immediately follow: “We are justified, (it is argued), in maintaining that only what is in ourselves can be perceived immediately, and that my own existence is the sole object of a mere perception” (367A). This aligns the text with the Cartesian senses of “inner” and “outer” and does so in a subject-centered fashion.

But importantly, the next lines confirm that It is from within this perspective that Kant finds the existence of our perceptions themselves, not merely their unknown cause, to be uncertain:

The existence, therefore, of an actual object outside me (if this word ‘me’ be taken in the intellectual [not in the empirical] sense) is never given directly in perception. Perception is a modification of inner sense, and the existence of the outer object can be added to it only in thought, as being its outer cause, and accordingly as being inferred”

A367

Again, recognizing that Kant has a Cartesian perspective in mind helps to clarify What he means when he refers to an “actual object outside me.” In this case it is not the unknown cause of our perceptions, but perceptions themselves whose existence is considered uncertain. It is not the perception of the object that is doubtful, but whether it exists, i.e. is not simply an illusion of some kind. As he goes on to say, its existence can only be added to it “in thought” or as we might say, “theorized.“

Its existence is “added to it only in thought” because, as claims 1 and 2 make clear, idealism (considered here as initiated by Descartes) is based upon a causal theory of perception. For the idealist, what is perceptible is possibly the effect of some external cause which is unknown to our perceptual faculties. The second premise [2] appears to be referring to the unknown causes of our perception where Kant writes of “outer appearances,” and therefore somewhat misleadingly, but the phrase “ideality of outer appearances” in the conclusion refers precisely to an uncertainty about the reality of our perception founded upon skepticism. The ideality of our perceptions is founded upon their uncertainty as [4] makes clear and as is indicated by the ensuing contrast with dualism.

Dualism (5) might be seen as best exemplified by Locke’s approach to perception (introduced above), which involves the supposition of a cause-effect relationship, but also finds it possible to claim that some objects in our perception exist independently outside ourselves within that framework.

A dilemma arises between the idealists and realists: the idealist can gain a solid footing regarding the existence of our perceptions, but only at the expense of not being able to certify that any given perception we might have is not merely an illusion, thus opening the door to a general skepticism about our perception of the world. This is very much the Cartesian predicament. We might attempt to solve it by a supposition such as the one Locke made, namely that the quantitative features of objects (their primary qualities) give us access to their independent reality. But this kind of solution only leads us back to questions about the uncertainty of our senses. As Berkeley noticed, if all perception is mind-dependent, then it is equally subject to the same mind-dependent uncertainty.

An Objection to Idealism

Berkeley’s approach was to simply regard all our perceptions as representational. Kant describes the Berkeleyan idealist’s position, an approach he endorses, as follows:

He considers this matter and even its inner possibility to be appearance merely; and appearance, if separated from our sensibility, is nothing. Matter is with him therefore only a species of representations (intuition), which are called external, not as standing in relation to objects in themselves external, but because they relate perceptions to the space in which all things are external to one another, while yet the space itself is in us.”

A370

As the last lines of the quotation indicate, for the Berkeleyan idealist, since our ideas/perceptions of the world constitute the only reality of our experience to which we have any access, they may be considered the only basis for our potentially true beliefs or any knowledge we might claim to possess about the world. “Appearance,” in a certain sense, is reality for the idealist.

But, of course, if what we perceive does not truly exist, nothing at all may be true of the reality of our phenomenal perceptions. For example, what is the truth value of an assertion such as “This apple is red” said of an apple that doesn’t exist, but is only a creation of our own mind?

Certainly, red cannot be considered an attribute of a non-existent apple. If the idealist is always uncertain about the existence of objects in his perception (see points 1-3 above) then the example just given might be said to apply to our entire experience of the world, thus defeating the possibility of knowledge. This is an objection is perhaps the strongest card that realism has to play against the idealist. What sense is there in talking about the phenomenal reality of our perceptions as a basis for knowledge if the existence of those perceptions remains in doubt?

A Reply

But notice that the idealist remains “uncertain,” hence agnostic, about the existence of that which causes our perceptions. The idealist does not claim that such causes do not exist or that they cannot exist, but only that we simply have no way of knowing whether they do or not.

It should be recognized that Kant takes this kind of agnosticism to be a feature not only of Berkeleyan idealism, but of idealism in general. And indeed, this seems to be the most consistent position regarding our knowledge of the reality of our senses. In a Cartesian sense, we might always be deceived by our senses on any given occasion without any way of knowing it (apart from taking recourse to a non-deceiving God as a guarantor of their truth); and again it might be possible that, as some contemporary philosophers as well as physicists have claimed, we may possibly live in a simulation.

But the idealist does not claim that we are necessarily led to affirm the unreality of the “external world”; only that Cartesian doubt leads us to a position where we cannot affirm or deny it of any given perception. From a pragmatic standpoint, this state of undecidability justifies an “as if” approach to the project of knowledge, since we certainly do observe regularities in our experience and we have of course benefited from the application of mathematical models to it.

An understandable reaction might be to shut the door to such concerns and sequester them in the world of philosophical speculation. But perhaps in opening up the question itself, we arrive at an event horizon: at a certain point we arrive at a place intellectually from which the forward momentum of our own questioning carries us forward in spite of any disinclination to pursue it further. To perhaps extricate ourselves (not to presume too much upon the reader’s state of motivation) consider the idealist’s argument from another angle. The nature of perception itself appears to make any would-be access to a Cartesian external world a theoretical impossibility. It has to be asked, “What would it mean to access the causes of our perceptions?”

Ascertaining their existence would necessarily require an ability to perceive that which causes our perceptions yet somehow not in a way that does not alter it by the very fact that we are perceiving it—an impossibility given the representational nature of perception. What could make the existence of something perceptible to us that cannot, even in principle, be perceived? It would seem that the realist concept of what it takes to acquire experiential knowledge places us in an impossible contradiction from the very start. Yet, the idealist position yields, as Kant acknowledges, only uncertainty about the very existence of which we perceive.

2.

Kant’s project in the Critique of Pure Reason is to provide a transcendental foundation for acquiring knowledge of the world as we encounter it representationally. But the conceptual work necessary for justifying such a foundation necessarily points back to the dialectic between realists and idealists.

2.1 Let’s begin by considering his characterization of what he calls the “transcendental object,” Kant’s placeholder for the thing in itself. The transcendental object might be thought of as that which underlies our perception (inner or outer) as its unknown object, somewhat like the traditional Aristotelian notion of a substratum of material bodies. The notion of a transcendental object can only be thought of as indicating an object in counterfactual terms: it is the object we would perceive if we could somehow get beyond the veil of perception, to get at what it is in itself.

The entire reason for positing such an object at all is to allow for the possibility of something that would act as the would-be cause of our perceptions in order to allow for the possibility that they might have a real existence beyond merely a perceptual–objective being. As Kant writes,

Neither the transcendental object which underlies outer appearances nor that which underlies inner intuition, is in itself either matter or thinking being, but a ground (to us unknown) of the appearances which supply to us the empirical concept of the former as well as of the latter mode of existence.

A379-380

It thus provides an ontological basis for Kant’s strategic agnosticism, which allows him to bracket the question of the existence of an external cause of our perceptions while not closing the door to its possibility at any given moment.

One of the basic critical principles that underlies the Paralogisms is that reason runs into difficulties from which it cannot extricate itself when it attempts to go beyond the limits of our possible empirical experience. When reason attempts to treat noumenal objects of which we have no experience as though they were quasi-phenomenal objects and reason accordingly, it ventures onto the seas of unsupported speculation.

When the realist treats the external causes of our perceptions as if we could perceive them, he falls into precisely this trap. Their proper standing for us ought to be as negative noumenal objects—objects regarded conceptually, transcendental objects, while bracketing the question of their existence and their properties. This is, in other words, the trap into which the realist falls when he takes the transcendental object to be a phenomenal thing in itself.

As usual, Kant’s remedy is not to go beyond the limits of our possible experience, but to leave the limits established by transcendental idealism intact, that is, to count all our perceptions as having the status of representations while not venturing to speculate about the nature and properties of things in themselves. In doing so, we consider the world revealed by our perceptions to be our reality, the world as it exists for us, since we cannot access any sensory world at all except by our perception of it.

2.2 This is the possible basis for Kantian response to the “two worlds” interpretation of idealism. The simple fact that must be recognized is that whatever we perceive for Kant is perceived as a representation. This means that the only world that we can possibly perceive is a representational one, necessarily shaped by the forms of perception and the categories of our understanding. No other “world” can exist as a world for us at all. Even if it were revealed that our perceptions were being manipulated by an evil genius as Descartes discussed it (or that we were a brain in a vat, etc.), the revelation could only occur within reality as we can possibly experience it.

2.3 Thus, when it comes to the question of whether and how our perceptual reality exists for the transcendental idealist, an idealist for whom the existence and reality of phenomena is supported by a transcendental object, we can say two things:

1. That the only reality to which we have any access is the reality of our representations.

2. Kant’s strategic agnosticism gives us our only foundation for asserting the reality of phenomena against the PEW.

These two principles give us the basis for understanding a Kantian approach to the reality of our perceptions. On the one hand, Kant acknowledges that we know nothing at all about what he calls things in themselves since we have no perceptual access to them and cannot; on the other, he finds a way to assert at least the potential existence of all our perceptions by recasting the thing in itself as a transcendental object.

Regarding our everyday experience, the Kantian position is that our perceptions are always representational, but regarding them as such does not alter our everyday perception of reality as we find it. It “leaves things as they are,” so to speak. It leaves us with a basis for doing scientific reasoning in so far as the existence of things can be verified by sensing them representationally.

If we consider that we might always doubt the ultimate reality of our perceptions (taking up the PEW), transcendental idealism pleads the fifth, so to speak, with its strategic agnosticism. In doing so, Kant remains true to the broader themes of the Critique of Pure Reason: once the unknowability of things in themselves is recognized and acknowledged, it should also be recognized that attempting to characterize them further than describing them as transcendental objects leads us into a realm of speculation that can never be given any positive foundation.