Kant made simple

Yes, this is possible! Only after reading Will Durant's excellent essay on Kant in "The Story of Philosophy" did I realise that ordinary people like me could understand this obscure philosopher. The simple presentation of Kant's thought on this page is entirely based on Will Durant. A lot of the text comes verbatim from Durant (eg all the elegant language). The goal is to make Kant's thought perfectly clear and understandable. Purists will say that this simplicity is simplistic. Judge for yourself. Be warned: this is not Kant, but Kant seen first through the filter of Durant, then through me.


Durant: "Never has a system of thought so dominated an epoch as the philosophy of Immanuel Kant dominated the thought of the nineteenth century."

By the time of the publication of Kant's masterwork, "Critique of Pure Reason" in 1781, the Enlightenment had thoroughly undermined Christian belief. As Durant puts it, "Religious faith and hope, voiced in a hundred thousand steeples rising out of the soil of Europe everywhere, were too deeply rooted in the institutions of society and the heart of man, to permit their ready surrender to the hostile verdict of reason; it was inevitable that this faith and this hope, so condemned, would question the competence of the judge, and would call for an examination of reason as well as religion."


The book's title refers to a critical analysis of pure reason, by which is meant knowledge that does not come through the senses, but knowledge that is ours due to the inherent nature and structure of the mind. Kant rejects the view of Locke and Hume that all our knowledge is derived from the senses. However, Kant granted Hume's point that absolute certainty of knowledge is not possible if knowledge comes from sensation, from an independent external world that owes us no promise of regularity of behaviour. We could feel a stimulus here, another there, but there is no promise of repeatability or connection. Kant's Critique is an analysis of the origin and evolution of concepts and of the inherited structure of the mind.

Kant's crucial first point

Experience gives us nothing but separate sensations. It tells us what is, but not that it must be what it is, and not otherwise. Hence it gives us no general truths. These must be independent of experience, ie apriori. Kant takes mathematics as an illustration of how far we can advance independently of experience. The truths of mathematics are absolute and do not need to be verified by experience. Two plus two will always be four regardless of any future experiences we may have. Kant argues that this character of absoluteness and necessity comes from the inherent structure of our minds. The mind of man is not passive wax upon which experience writes its whimsical will. It is an active organ which moulds and coordinates sensations into ideas, an organ which transforms the chaotic multiplicity of experience into the ordered unity of thought. It performs this process by following its own inbuilt procedures.

According to Kant the truths of mathematics derive their necessary (ie apriori) character from the inherent structure of our minds, from the natural and inevitable manner in which our minds must operate. (It did not seem to occur to Kant that our minds could be inherently faulty.)

Two stages of knowledge

Kant identified two stages in the process whereby our mind works the raw material of sensation into the finished product of thought. The first stage is the coordination of sensations by applying to them the forms of perception - space and time. The second stage is the coordination of perceptions by applying to them the forms of conception - the categories of thought.

Stage 1

A sensation is merely the awareness of a stimulus, such as a taste on the tongue, pressure on the hand, or a flash of light in the eye. These scattered sensations do not constitute knowledge. They are all that the infant has in the early stages of its development, before it recognises objects. The mind groups the various sensations about an object, such as an apple. The sensations of odour, pressure, light and taste are united to constitute a "thing", which we call an apple. There is now an awareness not so much of a stimulus as of a specific object. This is what Kant means by a perception.

The process by which the scattered sensations came to be ordered into a perception is not a property of sensations themselves but relies on the activity of the mind. Firstly, not all the sensations are accepted; most are ignored. Myriad forces play upon our bodies at any moment, causing a storm of stimuli, yet only those selected can be moulded into perceptions suited to our present purpose, or that bring messages of danger. The clock is ticking and we do not hear it; but that same ticking, no louder than before, will be heard at once if we listen for it.

Kant believed that the mind uses two primary methods for the classification of the material presented to it: the sense of space, and the sense of time. Space and time are not things perceived but modes of perception, ways of putting sense into sensation. Space and time are apriori because all experience presupposes them. It is inconceivable that we should have any future experience that will not involve them. We never see empty space, only objects and background. We infer that there is 'empty' space between objects, but we do not see it.

Stage 2

In the second stage, the mind raises the perceptual knowledge of objects into the conceptual knowledge of relationships, sequences and laws. Just as the mind arranged sensations around objects in space and time, so in the second stage the mind arranges perceptions (objects and events) about certain basic ideas. According to Kant these are: unity, plurality, totality, reality, negation, limitation, substance-and-accident, cause-and-effect, reciprocity, possibility, necessity, and contingency.

Kant's Model These are Kant's famous twelve categories. They are subjective in the same sense in which space and time are, ie our mental constitution is such that they are applicable to whatever we experience, ie they are the means by which we process our experience. Yet there is no reason to suppose them applicable to things-in-themselves. The categories are the pre-existing structures in the mind into which perceptions are received, and by which they are classified and moulded into the ordered concepts of thought. Objects serve as the building blocks of all our thinking and knowing. The categories are the bridge to the ideas that we have of the world. All our understanding, all theory is mediated by them.

Summing up

Sensation is unorganised stimulus, perception is organised sensation, conception is organised perception, ie knowledge. At the next level, science is organised knowledge. At each stage there is a greater degree of order and unity. This unity cannot come from things-in-themselves, for these are known to us only as bare sensations. It is our mind that imposes order, sequence and unity onto raw experience. The world does not have order of itself, but because thought creates it.

The world is a construct

The laws of thought are in effect the laws of things (ie perceptions), for things are only known to us through the medium of thought, which must obey these laws, since they are inherent in the structure of the mind itself. Kant concludes that the principles of science are necessary because they are ultimately the laws of thought, which are presupposed in every experience. Science is absolute and its truth is everlasting.

Yet the certainty and absoluteness of logic and science are paradoxically both limited and relative. They are limited strictly to the field of actual experience and relative to our human mode of experience. In other words, the world as we know it is a construction, a product to which the mind contributes as much by its moulding as things-in-themselves contribute through stimuli. (We perceive the building as rectangular, whereas we see a trapezium.) Kant wrote, "It remains completely unknown to us what objects may be in themselves and apart from the receptivity of our senses. We know nothing but our manner of perceiving them." The moon as known to us, is merely a bundle of sensations, unified by our native mental structure through the elaboration of sensations into perceptions, and of these into conceptions or ideas. As a result, the moon is for us merely our ideas.

Kant does not doubt the existence of the external world; he merely asserts that we know nothing about it except that it exists. A goodly part of every object is created by the forms of perception and understanding. We know the object as it manifests in our mind; what it is before being moulded by our mind we cannot know.

Science is not about reality

Science is naive: it supposes that it is dealing with things-in-themselves, yet the whole material of science consists of sensations, perceptions and conceptions. Schopenhaeur wrote, "Kant's greatest merit is the distinction of the phenomenon from the thing-in-itself." Put another way, our minds always deal with maps, never with the territory called reality.

Antinomies show the limits of our knowledge

Antinomies (paradoxes) arise when science tries to go beyond experience. When we attempt to decide whether the world is finite or infinite in space, thought rebels against either conclusion. For beyond any limit we are driven to conceive something further; and yet infinity itself is inconceivable. The same applies to the question of whether time began at a certain point.

Kant's solution to these paradoxes is to recall that space and time are modes of perception, which must enter into all our experience. The dilemmas arise from supposing that space and time are external things independent of perception. We shall never have any experience which we shall not interpret in terms of space and time; yet we must remember that these are not things out in reality but modes of interpretation and understanding. In other words, because space and time are not aspects of things-in-themselves, we shouldn't try to extend their application beyond the sphere of our experiences. Beyond our accumulated human time-span, time itself is not applicable as an ordering principle.

Likewise, substance, cause and necessity are finite categories, modes of arrangement and classification, which the mind applies to objects (which arise from sense experience). They are reliably valid only to the phenomena that appear to such experience. We cannot apply these conceptions to the world of things-in-themselves, ie to ultimate reality. Hence all the purported rational "proofs" of God's existence are invalid.


If Kant wanted to rescue religion then he had to find another basis for it. The one he chose was morality. Faith must be put beyond the reach of reason; it must be derived from the inner self by direct perception and intuition. He purports to derive the existence of God from the fact that each of us has a conscience. (His reasoning is so unconvincing that I won't bother to reproduce it here.)

Schopenhauer sums up: "Kant discloses the groundlessness of speculative theology, and leaves popular theology untouched, nay even establishes it in a nobler form as a faith based upon moral feeling."


Kant's ethics are also famous. He coined the term "categorical imperative", the unconditional command of our conscience to act "as if the maxim of our action were to become by our will a universal law of nature" (Kant). In other words Kant's criterion of morality is that an action is moral if it is desirable that it be a universal rule of behaviour.

Kant's Model

"A large part of Kant's work addresses the question 'What can we know?' The answer, if it can be stated simply, is that our knowledge is constrained to mathematics and the science of the natural, empirical world. It is impossible, Kant argues, to extend knowledge to the supersensible realm of speculative metaphysics. The reason that knowledge has these constraints, Kant argues, is that the mind plays an active role in constituting the features of experience and limiting the mind's access to the empirical realm of space and time."

- Dr Matt McCormick in The Internet Encyclopedia of Philosophy

Durant's conclusion

Durant concludes that even now "much of the great edifice remains; and the 'critical philosophy' represents an event of permanent importance in the history of thought." I agree.

Tad Boniecki
See my comments on Kant.

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