On The Ideal of Pure Reason

Kant’s chapter, “On the Ideal of Pure Reason,” best known for his critique of the ontological argument, has a greater, more expansive importance for the Critique as a whole than might be recognized. Section 2 may rightfully be considered one of the most important sections of the Critique. It can certainly be argued that its true importance lies in Kant’s development of the notion of an ens realissimum as a properly transcendental first principle that grounds the reality of everyday perceptual objects. By developing the concept of a metaphysical first principle as a transcendental one, he provides a fuller context for understanding the role of things in themselves and a broader context for understanding his refutation of idealism. This is at any rate what will be shown in what follows.  

Contents:

1. The Ens Realissimum as a Purely Intelligible First Principle of Being and Intelligibility
2. The Ens Realissimum as a Principle of the Intelligibility of all Things
3. Nevertheless, a Purely Intelligible Principle
4. The Ideal of Pure Reason as an Ontological First Principle
5. Another Look at the Refutation of Idealism 

The Ens Realissimum as a Purely Intelligible First Principle of Being and Intelligibility

Kant’s text tells us that the ens realissimum is a principle that grounds the independent reality of all things. This is most explicitly stated where he writes that not merely being, but absolute being belongs to it as a predicate (B604). As something that exists absolutely, it can be said to have a mind-independent being. As such, it is likewise capable of grounding the independent reality of all objects in our experience. It is because of its mind-independent reality that it can be characterized as a thing in itself (a thing with a mind-independent reality of its own) in a meaningful way. In fact, its only reality for us is one that can be grasped by pure reason. Consider this where Kant writes as follows:

the concept of what possesses all reality is just the concept of a thing in itself as completely determined; and since in all possible [pairs of] contradictory predicates one predicate, namely that which belongs to being absolutely, is to be found in its determination, the concept of an ens realissimum as the concept of an individual being is therefore a transcendental ideal which serves as a basis for the complete determination that necessarily belongs to all that exists.”

B604

The fact that they may serve as a basis for the complete determination of all that exists underscores its relationship, as a thing in itself, to other cases in which Kant discusses the (inaccessible) reality of things that exist for us as representations, over and above our experience of them (see, for example, Bxxvi, B164, and A380 in Paralogisms A).

The Ens Realissimum as a Principle of the Intelligibility of all Things

Kant gives us the basis for thinking that the ens realissimum functions as the ultimate ground for the intelligibility of all things where he writes that it is the “basis for the complete determination that necessarily belongs to all that exists” (as quoted above). The “determination” of things may be understood as the discovery and attribution to them of their properties. It is certainly possible that Kant had Locke’s distinction between real and nominal essences in mind here. The complete determination of all that exists could possibly coincide with a theoretical final state of scientific development of the sort contemplated by Putnam and others. 

Certainly the philosophical currents of today’s dialogues concerning science and the role of interpretation might indeed find reason to doubt that a stage of complete determination could ever be reached. But all that Kant is really committed to here is the principle that if there is some “most real being,” which is posited as a first principle of the intelligibility of all beings then such beings are, in principle, intelligible, which may serve to underwrite the activity of reason itself. If there is a genuine reality to the Being of beings that justifies the attempt to discover something intelligible in them at all, our inquiry into their reality has an object (the “complete determination” of all things). Hence the activity of our reason has its ultimate justification. 

Nevertheless, a Purely Intelligible Principle

However, it should be observed that the Kant’s ideal of reason, the ens realissimum, is also a merely heuristic principle. Kant writes,

It is obvious that reason, in achieving its purpose, that, namely, of representing the necessary complete determination of things, does not presuppose the existence of a being that corresponds to this ideal, but only the idea of such a being, and this only for the purpose of deriving from an unconditioned totality the complete determination of the conditioned totality, that is, the totality of the limited.”

B606

Thus, the ens realissimum functions as a purely intelligible principle, but one that stands to our understanding as having an “as if” value. While Kant finds it to be necessary for the possibility of achieving any true understanding of the world of our experience, no experience can serve to reveal its full reality to us. The assumed existence of an “unconditioned totality,” intelligible purely as a posit or an axiom of pure reason, is related to our experience as the basis for the “complete determination” of it as a “conditioned totality.” Finally, (returning to B604 as quoted earlier), it is by virtue of being considered as a thing in itself that it can be understood as possessing “all reality” and as “completely determined.”

The Ideal of Pure Reason as an Ontological First Principle

But the ens realissimum is not only a principle of intelligibility; it is also an ontological first principle, the ground of the being of all things. Kant’s argument is based upon the idea that a first necessary being is necessary as the primary actual being whose being makes possible the possibility of all things. The reader may have early on suspected that Descartes’ ontological proof may have had a hand in Kant’s formulation of his concept of an ens realissimum from the way in which the former argues from his existence/reality to the necessity of some source (God) of the same existence/reality. As such, the role of the ens realissimum in Kant’s system mirrors the role of the Good for Plato. 

The reasoning behind the ontological necessity of an ens realissimum is similarly that some source of the being/reality/existence of all things must exist as the ultimate source of their being and so possess “all reality” (as quoted quoted from B604 above). We find this suspicion confirmed in B616 where Kant writes,

if we take the issue as being that which is here stated, namely, first, that from any given existence (it may be merely my own existence) we can correctly infer the existence of an unconditionally necessary being; secondly, that we must regard a being which contains all reality, and therefore every condition, as being absolutely unconditioned, and that in this concept of an ens realissimum we have therefore found the concept of a thing to which we can also ascribe absolute necessity…”

B616

But again, as was the case in the Antinomies, while Kant regards this as an argument that establishes the necessity of a first cause, he does not take it to be conclusive as establishing the existence of such a cause—we might just as well argue for the necessity of an infinite series of contingent causes or simply declare its reality to be purely speculative because of the way it transcends any possibility of empirical confirmation. 

This is why we find Kant writing that

The supposition which reason makes of a supreme being, as the highest cause, is, therefore relative only; it is devised solely for the sake of systematic unity in the world of sense, and is a mere something in idea, of which, as it may be in itself, we have no concept. This explains why, in relation to what is given to the senses as existing, we require the idea of a primordial being necessary in itself, and yet can never form the slightest concept of it or of its absolute necessity.”

B707

While we have no sensible access to the reality of such a being as it might be in itself, the very notion of an “in itself” gives reason a theoretical justification to carry on its work of bringing unity to the understanding of our experience. The idea of totality and unity justifies, for Kant, the search for it in our experience.

Another Look at the Refutation of Idealism 

Understanding the role of the ens realissimum provides a crucial piece to the total puzzle of how to understand Kant’s response to “Idealism,” which he sees as a form of skepticism about the independent existence of any perceptible object. Let’s take another look at what Kant tells us about things in themselves in the Transcendental Aesthetic in his chapter on Space. The most important points can be conveniently summarized as follows: 

1. Space “does not represent“ a property belonging to things in themselves or to their relation to one another (B42).
2. In fact, spatiality is a property only of perceived objects. 
3. This means that things as they are in themselves are entirely inaccessible to our sensibility. Spatiality is the most basic, fundamental property of things, without which our perception of any object would not be possible. 
4. Furthermore, our outer intuition of perceived objects requires that our sensibility be affected by something. As Kant writes, “It is therefore, solely from the human standpoint that we can speak of space, of extended things, etc. If we depart from the subjective condition under which alone we can have outer intuition, namely liability to be affected by objects, the representation of space stands for nothing whatever” (B42).
5. The “objects” Kant has in mind in B42 are none other than perceptible objects considered as things in themselves. Space is a precondition for any sensible property of things and the objects in the quote considered as affecting us are contemplated as they might be prior to our sensibility being affected by them. Since they are objects considered as having a reality of their own apart from our experience of them, they are considered as things in themselves. 

The idea of objects considered as things in themselves turns out to be necessary for Kant because something must affect our sensibility if we are to have any perception of anything (again, see the quotation above from B42). Things in themselves may be taken to be the necessary coefficients of representability itself. While they are not accessible to our perception, they are comprehensible by our reason as a necessary condition for any representation of an object to occur. 

But their necessity (hence, the basis for justifying them as an assumption of reason) has a broader reach. They are necessary as a way of grounding our perception in an extra-mental reality, perhaps the only true basis for overcoming skeptical idealism. Empirical objects have an “objective validity” (B44) for us within the framework of our empirical experience of space time and their objectivity, such as we may experience it, belongs to a particular place and time inasmuch as we perceive them. But their reality as objects is entirely due to the supposition that our sensibility is first affected by something outside ourselves. 

This reading is confirmed by a consideration of Kant’s section titled the “Refutation of Idealism.” In the Refutation, Kant makes it his explicit aim to attack idealism as asserting either the non-existence (Berkeley) or doubtfulness (Descartes) of perceptible objects. Kant responds to their positions on the “problem of the external world” directly in note “a” (in B277) by contrasting (a)  the immediacy of our outer sense with (b) the mediated nature of our imagination. 

Our imaginative capacity, he argues, relies upon our sensibility for its content.  

It is clear, however, that in order even only to imagine something as outer, that is, to present it to sense in intuition, we must already have an outer sense, and must thereby immediately distinguish the mere receptivity of an outer intuition from the spontaneity which characterizes every act of imagination. ” 

B277

From the mediacy of imagination Kant infers the priority of outer over inner sense. Hence, our experience of the world of sensible objects cannot be originally imaginary, but must be based upon our capacity for sensation, which is a receptive capacity, not an active one. 

The priority of perception over imagination is an important piece of Kant’s argument against idealism. It is his basis for showing that we have “experience, and not merely imagination of outer things” (B275).  It is thereby a basis for showing that “even our inner experience, which four Descartes is indubitable, is possible only on the assumption of outer experience” B275)

Thus, when Kant argues (a) that we are conscious of our own existence as something determined in time and (b) that time presupposes something permanent, and (c) that our perception of something permanent is “possible only through a thing” outside ourselves, he is to be read as saying that our very concept of ourselves as thinking beings in time requires a perception of something both permanent and real outside ourselves, thus undermining the basis for idealism.