Constructive Skepticism

Descartes seems to simultaneously seek an absolutely certain knowledge and direct a withering doubt at anything which presents itself as certain knowledge: not a contradiction, but a tension to be sure.

Yet Descartes saw his skepticism as constructive rather than destructive: those bits of knowledge which survived it would be certain, and would be the unshakable foundation stones for a new philosophical system. Russell Shorto writes:

It was necessary for him to prove both the existence of God and the innate goodness of God, for, given the corrosiveness of Cartesian doubt, these were the only assurances we have that the material world really exists. So his work has a theological grounding: not only do the world and science depend on God, but so does Cartesian philosophy.

If chemistry and physics are to bring us any knowledge, Descartes writes, it will be upon this basis: for him, the “divine spark” may be characterized as certainty. One of his followers, Nicolas Malebranche, would refine this theme:

To talk of Cartesian dualism is somewhat misleading; Descartes actually wrote that the universe consisted of not two but three substances: mind, body (that is, the material world), and God. God is the guarantor that the mind and the world can interact meaningfully - that we can reach truth using the power of reason.

Malebranche doesn’t seem to realize that his insight into Cartesian thought has an odd resemblance to Plato’s tripartite soul, and Shorto, in summarizing Malebranche’s view, doesn’t point out the same similarity to Freud’s tripartite mind. The central role of God in Cartesian thought translates into the central role of God in modern philosophy:

It would be wrong to imagine that the Enlightenment was antireligion. Its mainstream thinkers, as well as many if not most of the radicals, were antichurch, not antifaith. Their problem with religion was that it kept individual humans from exercising their own minds and applying their innate reason to understanding the world and their place in it. This criticism applied not only to Catholicism but also to Protestant theology.

Here Shorto relies on the somewhat sloppy shorthand of “Enlightenment” for “modern philosophy” or for “thinkers writing in era immediately after the death of Descartes.” The notion of the “Enlightenment” as a distinct historical era, even if we allow for some variations within the monolith, is so ambiguous as to be undefinable. But the point stands: there was an eager engagement in the concept of God, even as there was a violent rejection of institutionalized religion. Spinoza exemplifies this:

Spinoza insisted that there is such a thing as religious truth, but he also insisted that religious institutions were largely concerned with protecting their own position.

Descartes, who agreed with Aristotle very rarely, might have formulated the matter in terms of an Aristotelian golden mean: a healthy skepticism, even a bitter cynicism, about religious institutions does not entail a rejection of the concept of God. On the contrary, our assumption that the universe behaves in an orderly fashion (the laws of chemistry and physics) implies a theistic view.

Lost in Words

Trained philosophers are constantly confronted with the glaringly illogical writings which characterize both the popular press and contemporary politicians. Example follows example of inconsistency, faulty argumentation, ambiguity, and every other error which logicians teach their students to avoid. A recent example, from the autumn of 2010, is provided by Rand Paul in a newspaper column he wrote. Attempting to establish for his readers his location on the political landscape, he explains for several paragraphs that he is not a “Libertarian,” but rather a “Constitutional Conservative” — but never defines either term!

Fichte’s Categories

Although it is common, when studying the thought of J.G. Fichte, to consider his philosophical system as reduced version of Kant’s system - i.e., that Fichte’s system is Kant’s system minus the Ding an sich - it is also possible to see Fichte’s system as an augmented version of the Kantian system: “Kant plus something” instead of “Kant minus something.”

This becomes clear if we consider the role of time and space in the Kantian system: they are foundational in the psychology of perception, from them much else is deduced, and upon them much else is based. Time and space hold a prior position in Kantian metaphysics and epistemology, not only in the sense that they are located toward the front of the book (The Critique of Pure Reason), but also in the sense that they are the necessary condition for experience, perception, representation, and intuition. Time and space are not “real” in the sense of being noumenal, but rather are the structure or framework of the mind - or at least a part of such structure or framework - the machinery by which we process our sense-data into perceptions.

Bearing in mind, then, the centrality of space and time to the Kantian system, we see that Fichte writes, concerning those who consider ethical systems from a roughly Kantian point of view, that

I would like very much to know what those who assume a familiar air of superiority whenever they encounter any mention of “intelligible intuition” imagine our consciousness of the ethical law to be like, or how they are able to construct for themselves concepts such as “right,” “virtue,” and the like - concepts that they certainly to possess. According to them, there are but two a priori intuitions: time and space. They undoubtedly construct the [ethical] concepts in question within time, which is the form of inner sense. But they undoubtedly do not consider these concepts to be identical to time itself; they are only a certain way of filling time. With what then do they fill time in this case, and what underlies their construction of these concepts? The only a priori intuition that remains for them is space. Consequently, their “right” would have to turn out to be, let us say, square, while their “virtue” would perhaps have to be circular, in the same way that all of the concepts they construct on the basis of sensory intuition - the concept of a tree, for example, or of an animal - are nothing but certain ways of limiting space. But they do not really conceive of right or virtue in this manner. What then is it that underlies their construction of these concepts? If they observe correctly, they will discover that what underlies these concepts is acting as such, i.e., freedom. Both concepts, the concept of right as well as that of virtue, are for them determinate limitations of acting as such, just as all sensory concepts are for them determinate limitations of space. But how have they arrived at this foundation that underlies their construction of these concepts? One would hope that they have not inferred acting from the dead inertia of matter, nor freedom from the mechanism of nature. They must have obtained this by means of immediate intuition; consequently, in addition to the two intuition they recognize, there must also be a third.

Fichte points out that the quasi-Kantian ethicists cannot find an adequate foundation for moral thought in the two intuitions of time and space. (He seems careful not to attack Kant himself directly, either because he genuinely thinks that Kant is free from the errors of the later Kantians, or because Fichte’s respect for Kant is too great, or because a direct attack on Kant would not have been tolerated by Fichte’s contemporaries.) If time and space are the starting point for all mental processes, then there could be no moral thought: if there is moral thought, then there must be a third foundational intuition alongside the other two.

So Fichte builds his system on a three-legged stool, a philosophical tripod, and sees this as an advantage over the two-legged foundation which is supposed to support the Kantian system. Kant began his epistemology with the notion that space and time would be the framework, or would generate the framework, which the mind would use to perceive and understand. Fichte adds a third atom to this framework: an ethical intuition. This intuition will deal in some fashion with “action” and “freedom”.

Thus constructed, Fichte’s ethics will find their roots in the very foundations of his system. If the three feet of his system are time, space, and ethical intuition, then metaphysics and ethics will play the most central role in the system, relegating other types of philosophy to secondary roles, and Copleston will be correct in observing that Fichte has a “tendency ... to reduce religion to morals,” inasmuch as ethics are more foundational to the system than God is.

Offering a slightly different explanation of his addition to the Kantian system, Fichte reviews the attempts of Kantians to explain the self in the same manner in which they explain noumenal or phenomenal objects. Fichte objects that, if we treat the self the same way we treat a rock or a tree, we will miss important aspects of the self which make it a subject instead of merely an object.

If such an existence were ascribed to the self, it would cease to be a self; it would become a thing, and its concept would be abolished. Later, to be sure - not in time, but in order of dependence of thought - even the self, though still remaining, as it must, a self in our sense of the word, will also be credited with existence of this sort; in part with extension and subsistence in space, and in this respect it becomes a determinate body; in part with identity and duration in time, and in this respect it becomes a soul. But it is the business of philosophy to demonstrate and explain genetically how the self comes to thing of itself in this fashion; and so all this belongs, not to what we have to assume, but to what we have to derive. - It comes, then, to this: the self is originally a doing, merely; even if we think of it only as active, we already have an empirical concept of it, and so one that has first to be derived.

We have two arguments here: first, that we cannot create or justify the foundation of ethical concepts without adding a third intuition to the first two, i.e., adding “action” to time and space; second, we cannot explain or sufficiently express the nature of the self, i.e as active agent and knowing subject, without this third leg to the stool.

Fichte attempts - whether he succeeds or not, the reader may judge - to show that an accurate concept of self is impossible without his system:

The principle of life and consciousness, the ground of its possibility - is admittedly contained in the self; but this gives rise to no genuine life, no empirical existence in time; and any other kind, for us, is absolutely unthinkable. If such a genuine life is to be possible, we need for the purpose another and special sort of check to the self on the part of the not-self.

Fichte sees himself less as contradicting Kant, and more as extracting from Kant’s system that which is already hidden or latent within it. Thus he sees that Kant’s critical philosophy begins with the exploration of the mechanisms of the mind - e.g., how time and space are parts of the mind, or generated by the mind, and used by the mind to process experiences and sense-data into perceptions and representations. The mind is, then, essentially active; from this, Fichte proceeds to identify “action” as a fundamental or foundational intuition.

The New York Times and Pure Reason

Columnist David Brooks explores the question of why some religions are beneficial, generally bringing help to humanity, and other religions are useless or even damaging to the civilizations on this planet. He notes that

Many Americans have always admired the style of belief that is spiritual but not doctrinal, pluralistic and not exclusive, which offers tools for serving the greater good but is not marred by intolerant theological judgments.

He captures here a sentiment which characterizes some segment of our society. It seems to offer exactly those benefits one would hope to gain from a religion. But such religions eventually disappoint. What at first appears to promise a chance to harness civilization’s energies toward noble purposes turns out to be finally impotent, unable to organize the hoped-for charitable impulses. Or, even worse, it reveals itself to be blinding, rendering its adherents unable to perceive more nuanced moral realities.

Vague, uplifting, nondoctrinal religiosity doesn’t actually last. The religions that grow, succor and motivate people to perform heroic acts of service are usually theologically rigorous, arduous in practice and definite in their convictions about what is True and False.

Brooks refers to the latter set of religions, those which benefit mankind, as those with “rigorous theology”:

Rigorous theology provides believers with a map of reality. These maps may seem dry and schematic — most maps do compared with reality — but they contain the accumulated wisdom of thousands of co-believers who through the centuries have faced similar journeys and trials.

Rigorous theology allows believers to examine the world intellectually as well as emotionally. Many people want to understand the eternal logic of the universe, using reason and logic to wrestle with concrete assertions and teachings.

Rigorous theology helps people avoid mindless conformity. Without timeless rules, we all have a tendency to be swept up in the temper of the moment. But tough-minded theologies are countercultural. They insist on principles and practices that provide an antidote to mere fashion.

Rigorous theology delves into mysteries in ways that are beyond most of us. For example, in her essay, “Creed or Chaos,” Dorothy Sayers argues that Christianity’s advantage is that it gives value to evil and suffering. Christianity asserts that “perfection is attained through the active and positive effort to wrench real good out of a real evil.” This is a complicated thought most of us could not come up with (let alone unpack) outside of a rigorous theological tradition.

There is a slight confusion between religion and theology here: the two words are not synonyms. Overlooking that, Brooks here offers a fourfold definition: a belief which is systematic, rational, supra-contextual, and which approaches mysteries. Systematic beliefs can be codified in texts, which makes them publicly and objectively accessible. Rational beliefs respect the structures of the universe and of the human mind, and assess various explanations in light of these. Such beliefs provide a breakwater against the tides of conformity which sweep through societies on a regular basis. And such beliefs admit that there is possibly a limit to the powers of human reason, which means that being rational is being willing to admit the possibility of mystery.

Although religion is not morality - atheists can be very moral - there is some connection between religion and morality. Brooks notes this connection:

Rigorous codes of conduct allow people to build their character. Changes in behavior change the mind, so small acts of ritual reinforce networks in the brain. A Mormon denying herself coffee may seem like a silly thing, but regular acts of discipline can lay the foundation for extraordinary acts of self-control when it counts the most.

History will force us eventually to judge the net contributions of various religions. Some will have given benefits to the human race; others will have given misery. Just as no human being is morally pure - we all commit both good and bad actions - so no religion will be found pure. Even the best religions will have committed some evil, and even the worst religions will have given some benefit. No religion is perfectly evil, just as God is perfectly good. To judge a religion, therefore, is not to judge people, nor is it to judge God. We will find, in the end, that just as all humans are equal, not all religions are equal.

Science and Truth

Among modern (as opposed to post-modern) thinkers, the natural or observational sciences are taken as paradigmatic for empirical knowledge. Among those whose thought is formed by the indirect influence of John Locke and David Hume, the input of the five senses, disciplined by the “scientific method,” is treated - explicitly or implicitly - as the fount of rational knowledge.

Inasmuch as philosophical influences, when they have decayed into cultural influences, are transmitted in a confused and garbled manner, it follows that many of those most influenced do not even know the names John Locke or David Hume, are unaware of the unresolved tensions between Lockean empiricism and Cartesian rationalism, and treat the “scientific method” as an undisputed axiom - having never learned that even Isaac Newton, now an icon for the natural sciences, directly contradicted the more common forms the “method” in his famous statement about not making hypotheses. Thus I justify my use of otherwise superfluous quotation marks around the phrase.

Yet it is precisely those icons - which like many icons, are emptied of actual content in the process of being used as an icon - who would most undermine this notion of disciplined a posteriori thought being the paradigm for certain knowledge - again, the irony that Cartesian certainty would be found through Lockean methods! - Newton, Boyle, Kepler, Copernicus, Faraday, etc. They were far less certain of themselves and their thoughts than their disciples seem to be.

Or, to bring the matter up to date, as Karl Popper wrote:

All scientific statements are hypotheses, or guesses, or conjectures, and the vast majority of these conjectures ... have turned out to be false. Our attempts to see and to find the truth are not final, but open to improvement; ... and our knowledge, our doctrine, is conjectural; ... it consists of guesses, of hypotheses, rather than of final and certain truths.

The assumption that modern science is a finalized and certain method to gain knowledge is not universally embraced by those very individuals who are allegedly the source of that assumption. The writings of these founders of modern science clearly state their understanding that the conclusions of observational science were not certainties, and that there were other sources of knowledge in addition to such natural sciences.

A Brief History of Nothing

What do you know about nothing? Philosophers have been writing about nothing in particular for a long time.

Among the pre-Socratics (around 500 B.C.), Leucippus and Parmenides argued about whether a true vacuum was possible. This was an embryonic form of the discussion of nothing.

One of the earliest philosophers to write about nothing was Fridugis (also spelled Fredegis or Fredegisus), who lived in the early 800’s. He was a student of the noted philosopher Alcuin, and part of the revival of learning and intellectual life which occurred during the reign of Karl the Great (Charlemagne). He died in 834 A.D.

His major work is entitled “On Nothing and Darkness,” which hints already at the notion that as darkness is a lack of light, so nothing is a lack of something. Fridugis recognized that the investigation of nothing is, at least in part, a linguistic investigation. We are led, or misled, by the fact that “nothing” is a noun, and as such, represents a person, place, thing, or idea. So we are compelled to conclude that nothing is something:

This is the nature of the question: “Is nothing something or not?” If one replies: “It seems to me that nothing exists,” the very negation of it which he assumes to be the case forces him to admit that nothing is something in that he says: “It seems to me that nothing exists.” This statement is such as if he were to say: “It seems to me that nothing is something.” If it seems to be something how can it appear not to exist in some way? Consequently it remains that it seems to be something.

Fridugis proceeds along grammatical lines, establishing that "nothing" is a noun, and therefore - following Aristotle - the name of something, i.e., the word “nothing” names some thing. Taking this as sufficiently demonstrated, Frigudis goes on to ask what type of thing nothing is. It is, he writes, “something great,” because, given the fact that the known universe was called forth ex nihilo (out of nothing),

those which are the first and foremost among creatures have been created out of nothing. Therefore, nothing is something great and remarkable, and its magnitude from which so many and such noble things have been produced cannot be grasped.

Nothing, then, according to Fridugis, is the source of everything, and so, in some way, everything must have been contained, even if only in an embryonic state, in nothing. This eerily anticipates remarks written by a thousand years later Hegel.

Between Fridugis and Hegel lived Albert of Saxony in the 1300’s. He carried out a rather even-handed exploration of nothing, neither affirming nor denying much, but examining what nothing might imply or entail.

In several different books in the early 1800’s, Hegel devotes a number of pages to the topic of nothing:

Pure being, as it is mere abstraction, is therefore the absolutely negative: which, in a similarly immediate aspect, is just nothing. Hence was derived the second definition of the absolute: the absolute is nothing. In fact this definition is implied in saying that the thing-in-itself is the indeterminate, utterly without form and so without content - or in saying that God is only the supreme Being and nothing more.

(Hegel addresses here the philosophical system of Kant, in which “the thing in itself” is an object before it is processed by cognition of the mind, which is to say before it is placed into time and into space. The thing in itself lacks any of the properties which an object can have only if it is in time and in space - which is to say that the thing in itself is undefined and indeterminate.) Hegel writes that this “pure Being” is

in its indeterminate immediacy equal only to itself, and yet not differentiated in respect to other, and has no differentiation inside itself, nor towards anything external.

Any determination or content, which would posit any form of distinction or contrast, cannot be found in this “pure Being,” because it would no longer be pure. It would no longer be

maintained in its purity. It is pure indeterminacy and emptiness. - There is nothing to be perceived in it, if one can speak here of perception; or it is only pure empty perception itself.

And so nothing appears as the sole ingredient or content of pure Being!

Being, indeterminate immediacy, is in fact nothing, and no more nor less than nothing.

Hegel arrives at nothing by examining Being, just as Fridugis arrived at everything by studying nothing.

A century after Hegel, the philosopher Martin Heidegger researched nothing, and found it to be not merely a question in philosophy, but rather one of the central and foundational questions in philosophy, and specifically in that branch of philosophy known as metaphysics. Heidegger notes that modern science unwittingly includes nothing in its self-stated objects of study:

What is to be investigated is what-is — and nothing else; only what-is — and nothing more; simply and solely what-is — and beyond that, nothing.

Yet the study of nothing requires a different approach than the study of something. Different methods will be required.

we shall endeavour to enquire into Nothing. What is Nothing? Even the initial approach to this question shows us something out of the ordinary. So questioning, we postulate Nothing as something that somehow or other “is” — as an entity (Seiendes). But it is nothing of the sort. The question as to the what and wherefore of Nothing turns the thing questioned into its opposite. The question deprives itself of its own object.

Heidegger’s exploration of nothing is perhaps the high point of such studies. He will explain to us that emotion has a role in informing us about nothing. He contrasts fear and anxiety (Angst). Fear has an object: we are afraid of something. But anxiety is when we have a sense of fear about nothing. So it is anxiety, in contrast to fear, which leads us to learn about nothing.

Following Heidegger, Jean-Paul Sartre took up the study of nothing. Contrasting Heidegger’s investigation of nothing with Hegel’s, Sartre writes:

Heidegger, while establishing the possibilities of a concrete apprehension of Nothingness, never falls into the error which Hegel made; he does not preserve a being for Non-Being, not even an abstract being. Nothing is not; it nihilates itself.

The reader is advised to study the works of Hegel, Heidegger, and Sartre, from which he can learn much about nothing.

The Limits of Reason

What can the human mind do? What can it not do? These questions have long engaged philosophers. The first question, however, tempts them to make ever-grander claims, while the second calls them to a humility and sobriety which doesn’t flatter the collective human ego. Of the many who’ve dealt with these questions, Immanuel Kant has achieved breakthroughs in assessing the capabilities of human knowledge. It is essential to examine Kant’s writings themselves, rather than summaries written by others. Here, we will make do with such second-hand overviews, trusting that you, dear reader, will then explore Kant’s texts.

Kant is understood against the historical background in which the two main currents of thought were Cartesian rationalism and Lockean empiricism. The former took mathematics as paradigmatic for a priori knowledge and certainty; the latter was concerned about the process by which gathering sense-data into perceptions could be formalized into something like the modern observational sciences. In opposition to each other, the philosophers had to then choose either to embrace metaphysical certainty at the cost of reliable knowledge of the perceivable world, or to embrace observational realities at the cost of any other form of reality. Dinesh D’Souza notes, regarding the latter view especially, that empiricists

may not recognize it, but there is a huge assumption being made here. These men simply presume that their rational, scientific approach gives them full access to external reality.

Which is to say, having sacrificed Cartesian metaphysics for the sake of empirical natural sciences, they may find that they have gotten a bad deal: this scientific method may not yield as much as they had hoped. Isaac Newton, after, warned against framing hypotheses - a foreshadowing perhaps of Kant’s more thorough critique. Whether through a naive direct realism, or a more nuanced indirect realism, or even a radical empiricism, a claim is made about the mind’s ability to gather information about the world.

Before Kant, most people simply assumed that our reason and our senses give us access to external reality — the world out there — and that there is only one limit to what human beings can know That limit is reality itself. In this view, still widely held by many in our society, human beings can use the tools of reason and science to continually find out more and more until eventually there is nothing else to discover. The Enlightenment fallacy holds that human reason and science can, in principle, gain access to and eventually comprehend the whole of reality.

Kant’s Critique of Pure Reason was published in 1781, and urged a humility in making claims about what human reason can discover.

In fact, he argues, there is a much greater limit to what human beings can know. In other words, human reason raises questions that — such is the nature of our reason — it is incapable of answering. And it is of the highest importance that we turn reason on itself and discover what those limits are. It is foolishly dogmatic to go around asserting claims based on reason without investing what kinds of claims reason is capable of adjudicating. Reason, in order to be reasonable, must investigate its own parameters.

It is human nature to ask questions. We will ask many more questions than our reason can answer. We therefore can create two categories of questions: those answerable by human reason, and those not. If a question cannot be answered by human reason, we might then go on to ask whether it can be answered at all - and if so, how.

Kant begins with a simple premise: all human knowledge is based on experience. We gain access to reality through our five senses. This sensory input is then processed through our brains and central nervous systems. Think about it: every thought, even the wildest products of our imagination, are exclusively based on things that we have seen, heard, touched, smelled, or tasted. If we imagine and draw creatures from outer space, we can give them four eyes and ten legs, but ultimately we have no way to conceive or portray them except in terms of our human experience. It is an empirical fact that our five senses are our only lenses for perceiving reality.

More accurately, Kant writes that all knowledge begins with experience. Even that knowledge which has no basis in experience (Cartesian a priori mathematical certainties) arises in the course of experience. So all knowledge begins with experience, but some knowledge is based on experience.

Now Kant asks a startling question: how do we know that our human perception of reality corresponds to reality itself? Most philosophers before Kant had simply taken for granted that it does, and this belief persists today. So powerful is this “common sense” that many people become impatient, even indignant, when Kant’s question is put to them. They act as if the question is a kind of skeptical ploy, like asking people to prove that they really exist. But Kant was no skeptic: he saw himself as providing a refutation of skepticism. He knew, however, that to answer skepticism one has to take the skeptical argument seriously. The way to overcome skepticism is by doing justice to the truth embodied in it. Kant’s goal was to erect a dependable edifice for knowledge on the foundation of extreme skepticism.

Like Descartes, Kant finds a constructive use for skepticism. Like Hume, Kant asks if we have any justification for positing whatever ontology we may embrace. Unlike Thomas Reid, Kant denied that common sense provided enough justification.

Kant’s question about the reliability of human perception has been the central preoccupation of Western philosophy since Descartes. How do we know what we claim to know? Locke had famously pointed out that material objects seem to have two kinds of properties, what he called primary properties and secondary properties. Primary properties are in the thing itself, whereas secondary properties are in us. So when we perceive an apple, for example, its mass and shape are part of the apple itself. But Locke ingeniously pointed out that the redness of the apple, its aroma, and its taste are not in the apple. They are in the person who sees and smells and bites into the apple. What this means is that our knowledge of external reality comes to us from two sources: the external object and our internal apparatus of perception. Reality does not come directly to us but is “filtered” through a lens that we ourselves provide.

Kant writes to the effect that the human mind provides a great deal of structure to what we perceive as reality. The structuring process begins with space and time - two products of the mind. What we naively perceive as one object’s being “there and then” and another object’s being “here and now” is not merely our five senses importing information about the world, but rather largely a creation of our mind. Methodically internalizing the notion that time and space are not facts about the world, but tools created by our mind for the purpose of organizing sense-data, will change our assessment of observational natural sciences regarding their ability to give us information about the world.

Philosopher George Berkeley radicalized this mode of inquiry: “When we do our utmost to conceive the existence of external bodies, we are all the while only contemplating our own ideas.” Berkeley’s argument was that we have no experience of material objects that exist outside the perceptual apparatus of our mind and senses. Both the primary and the secondary qualities of objects are perceived in this way. We don’t experience the ocean, we experience only our image and sound and feel of the ocean. Berkeley famously concluded that we have no warrant for believing in a material reality existing independent of our minds!

Although Berkeley’s idealism can be seen as the organic consequence of the epistemology of his era, it would seem to Kant to be perhaps equally unwarranted: positing the existence of physical objects in the world requires justification just as much as positing the lack of their existence.

Hume completed Berkeley’s skeptical argument by applying it to human beings themselves. We have no experience of ourselves other than our sensations and feelings and thoughts. While we know that sensations and feelings and thoughts exist, we have no basis for postulating some “I” behind them that is supposed to be having those reactions.

Hume’s radical empiricism, while a direct descendant of Locke’s thought, took the matter to this arresting extreme. Berkeley had denied the existence of a material external world; Hume denied the existence of a self or perceiving mind. All that remained, then, was a collection of sensations, corresponding to no objects, and perceived by no subject.

Kant conceded Berkeley’s and Hume’s point that it is simply irrational to presume that our experience of reality corresponds to reality itself. There are things in themselves — what Kant called the noumenon — and of them we can know nothing. What we can know is our experience of those things, what Kant called the phenomenon.

At first blush, Kant is saying that not only can we not know what the external world is like, but also that we cannot even know if it exists. He embraces the extremes of Berkeley and Hume, but only as a starting-point: the constructive use of skepticism.

Our senses place absolute limits on what reality is available to us. Moreover, the reality we apprehend is not reality in itself. It is merely our experience or “take” on reality. Kant’s point has been widely misunderstood. Many people think that Kant is making the pedestrian claim that our senses give us an imperfect facsimile or a rough approximation of reality.

Not only would Kant claim that our senses limit what we can know, but also that the structure of the human mind limits knowledge as well. We can, for example, know or imagine only objects in space and time, and only in our particular type of space and time. It is important to understand what Kant is not writing: he is not dealing with, for example, the limitations on eyesight, that we can’t see further away, or with more magnification, or beyond the spectrum of visible light. That’s not his point - those are mere differences of degree. He is speaking about differences of kind - knowledge which is not only impossible for us to gain, but which is in principle impossible.

Kant’s argument is that we have no basis to assume that our perception of reality ever resembles reality itself. Our experience of things can never penetrate to things as they really are. That reality remains permanently hidden to us. To see the force of Kant’s point, ask yourself this question: how can you know that your experience of reality is in any way “like” reality itself? Normally we answer this question by considering the two things separately. I can tell if my daughter’s portrait of her teacher looks like her teacher by placing the portrait alongside the person and comparing the two. I establish verisimilitude by the degree to which the copy conforms to the original. Kant points out, however, that we can never compare our experience of reality to reality itself. All we have is the experience, and that’s all we can ever have. We only have the copies, but we never have the originals. Moreover, the copies come to us through the medium of our senses, while the originals exist independently of our means of perceiving them. So we have no basis for inferring that the two are even comparable, and when we presume that our experience corresponds to reality, we are making an unjustified leap. We have absolutely no way to know this.

What we know, then, as the laws of chemistry or physics, are actually psychological laws about the functioning of the mind. Given that I know only my perception of atoms or stars, the laws which I think regulate atoms and stars actually regulate only my perceptions of atoms and stars.

It is essential, at this point, to recognize that Kant is not diminishing the importance of experience or of the phenomenal world. That world is very important, if only because it is all we have access to. It constitutes the entirety of our human experience and is, consequently, of vital significance for us. It is entirely rational for us to believe in this phenomenal world, and to use science and reason to discover its operating principles. A recognized scientist and mathematician, Kant did not degrade the value of science. But he believed science should be understood as applying to the world of phenomena rather than to the noumenal or “other” world.

We understand that Kant is not denying the existence of an external world - he pointed out that we have no justification for denying its existence - but rather he is demonstrating the inability of reason to know about that world. Kant ultimately disagrees with Berkeley. Nor is he saying that we can know nothing about the external world - he is saying that our reason can know nothing about it. He leaves the door open for other types of knowledge.

For Kant, the noumenon obviously exists because it gives rise to the phenomena we experience. In other words, our experience is an experience of something. Moreover, Kant contends that there are certain facts about the world—such as morality and free will—that cannot be understood without postulating a noumenal realm. Perhaps the best way to understand this is to see Kant as positing two kinds of reality: the reality that we experience and reality itself. The important thing is not to establish which is more real, but to recognize that human reason operates only in the phenomenal domain of experience. We can know that the noumenal realm exists, but beyond that we can know nothing about it. Human reason can never grasp reality itself.

The warning is worth repeating, however, we have not yet looked directly at the texts written by Kant; we have here quoted from a summary written by Dinesh D’Souza, who teaches at Stanford University. We have, in fact, seen that his summary needs a few small correctives along the way. This is the perpetual problem confronting those who would produce an accessible and popular explanation of a philosopher’s works: Kant’s text are hundreds of pages long, written with bizarre neologisms and interminable sentences. It is necessary to produce some type of popular summary, because these books will be forever inaccessible to some readers; yet while it is necessary to do so, it is also to some extent impossible.