53c7f-kantforpipesmokingImmanuel Kant (1724 – 1804 CE) was a German philosopher who was technically born in what was once Konigsberg, Prussia, today part of Russia and renamed Kaliningrad.  While Kant grew up in a devotedly Pietist family, a branch of Lutheranism that placed a great emphasis on individual morality and purity, he found himself drawn to Rationalism and in opposition to religious ceremony.  While a professor at the University of Konigsberg, Kant was always “indisposed” whenever it was his turn to participate in church services.

Kant Königsberg Monument StatueIt is said that Kant never traveled more than fifty kilometers from his hometown in his entire life.  He was known for being obsessively punctual, and legend has it that he would take his daily walks after lunch so routinely that housewives would set their clocks as Kant passed by their houses.  Kant would always walk alone, as he believed it proper and healthy to breathe through one’s nose in the open air and so kept his mouth closed outside.  He was also deeply disturbed by perspiration.  It is said that the only morning Kant broke from his usual strict routine was to purchase a newspaper announcing the outbreak of the French Revolution, an event that, like the work of Kant, had a great impact on Hegel, the next figure we will study.

Just as Locke is famous for his work in both epistemology and political theory, Kant is famous for his work in both epistemology and ethics.  While we will focus on Kant’s epistemology for the purposes of this class, just as we focused on Locke’s, we cover Kant’s theory of morality in the Ethics class, which we can briefly cover here just as we briefly covered Locke’s political influence.  Kant believed in strict, rule abiding morality, which he considered the true means of Christian salvation, not religious ritual.  Using our universal faculty of reason, Kant argued that we can come to understand absolute principles, morals to which we should always adhere no matter the consequences.


Kant argues that if we are rational, we are concerned with absolutes that are universal and ideal.  The example Kant gives is, “Do not lie”.  If we always lied, society would fall apart, and so we must always tell the truth if we choose to speak rationally.  A firm believer in duty, Kant argues that we must be moral no matter the consequences.  Even if we know that a lie might have a good chance at saving our own life or the life of another, immorality is never justified.  Needless to say, many find this stance a bit to dogmatic to put in practice.  John Stuart Mill, who we will study with Utilitarianism, argued for the opposite position, that the ends justify the means, and morality is only for the purpose of achieving happiness.

kant mill
Arabic Aristotle

Kant was primarily concerned with metaphysics, the laws of being.  Just as Plato’s Idealism was concerned with the heavens while modern Idealism was concerned with the mind, so too Aristotle’s metaphysics was concerned with the workings of the heavenly bodies, while Kant’s metaphysics was concerned with the limitations of the human mind.  This is similar to Locke, who was primarily interested in the limits of human knowledge and understanding.  Like Leibniz, whom Kant admired and studied, Kant believed in the Principle of Sufficient Reason, the Principle of Non-Contradiction and the rational, universal application of logic, which Kant thought Aristotle had nearly completed.  Later, Kant’s work would impact Schopenhauer, whose work would impact Wittgenstein, whose work would completely revolutionize logic, unbeknownst to Kant.


Like Descartes and Hume, Kant was well aware of ancient Greek Pyrrhonism, as well as the challenge that skepticism and the work of Hume posed to metaphysics and Rationalism.  Aristotle hated ancient Greek skeptics, arguing that they were “mere destroyers”, and no better than plants when it came to philosophy.  Upon reading the work of Hume, Kant famously wrote that he was woken from his “dogmatic slumbers”, now tasked to prove that there is objective truth beyond mere assumptions given that all beliefs are acquired through experience.  Kant’s work, like that of Descartes, is concerned with finding what can be defined as certain and objective in the face of doubting everything.  Specifically, Kant sought to rescue Leibniz’s Principle of Sufficient Reason and Principle of Non-Contradiction from being considered mere assumptions.  He argued that metaphysics could go beyond both dogmatism and skepticism to become ‘critical’, like Descartes questioning all truth to distinguish what is objectively true beyond all appearances.


In his early work, Kant wrote about philosophy and the natural sciences, reconciling the work of Newton with philosophy and theology.  Like Descartes, Kant argued that the regularity of the cosmos shows that it is intelligently designed and operates in a rational manner.  Strangely, in his old age Kant hypothesized that the use of domestic electricity caused strange cloud formations and epidemics of disease in cats, a theory which might have survived if Kant had lived in the days of the internet.

Kant silhouette

Awoken by the skepticism of Hume, Kant spent a ten year “decade of silence”, from 1770 to 1780, working on the first of his three Critiquesthe Critique of Pure Reason.  Originally, Kant thought the work would take three months.  This first Critique focused on objective rational inquiry exclusively separate from the influence of experience.  Kant’s second two critiques, the Critique of Practical Reason and the Critique of Pure Judgement, focused on the use of reason in practical matters. and .  The Critique of Practical Reason dealt with freedom and morality, and the Critique of Pure Judgement dealt with aesthetics, the study of beauty and art.  We focus on the first Critique, as we have been on epistemology.  Much as Descartes sought to incorporate while overcoming Pyrrhonian skepticism, Kant sought to incorporate while overcoming Hume’s Empiricism with Rationalism.  Kant argued that Hume was right about the world of experience, which can only be known subjectively and imperfectly, but not about the logical operation of reason, which we can know objectively and certainly.

Glasses Apostle

Recall that Locke compared the faculty of understanding to the human eye.  Kant’s conception of understanding is often illustrated with the metaphor of eyeglasses.  While we may not be able to know what the world looks like without our glasses, we can examine the glasses to see the frame through which we view the world.  Likewise, Kant argued that we can critically examine our faculty of understanding with reason to understand how our ideas must take shape, to understand both the basis of understanding and the motions of reason.  This would put metaphysics, such as the Principle of Non-Contradiction, “on the secure path of science”.  ‘Science’ in German is Wissenschaft, or “knowledge-base”.

Unlike Berkeley, Kant believes that there is a “thing-in-itself” beyond appearances, the Ding an sich in the German, using the Latin term noumena for the things themselves and phenomena for our perceptions of them.  Kant argues that we can never know the thing in itself, but we can know the way that we form ideas about appearances.  Next week, we will study Phenomenology, the attempt by Hegel, Merleau-Ponty and others to create a “science of appearances”.  Kant used another pair of Latin terms to distinguish between rational and empirical truth, to separate the objective from the subjective.  That which is known before and apart from all experience Kant labeled a priori, and that which is known after and through experience Kant labeled a posteriori.

Kant Critique of Pure Reason Plate

The central question of the Critique of Pure Reason is, “How are synthetic a priori judgements possible?”.  When we analyze a thing, we break it into its component parts.  When we synthesize a thing, we put many parts together to form a greater whole.  Kant wants to synthesize, to gather together, what can be known before and apart from experience about the human mind, thus Kant’s concern for the “synthetic a priori”.  In a sense, if we sat in a closet and thought, we would be able to form thoughts away from the world, and this would best show us the form our thought takes and thus the form of our world.

Coconuts on a bike

If we figure out elementary linear arithmetic in the dark, we may never be able to predict how many coconuts we will gather next Tuesday, but we can be certain that if we gather two coconuts and then three, we will have gathered five coconuts.  We can then reason that if we gather six more, we will have eleven, synthesizing additional mathematical truths via reason apart from the experience of gathering any coconuts. Thus, while Hume is right that whatever we think we may gather on a Tuesday is merely an assumption, Kant argues that if we are being objective, we cannot reason two and three together any other way than as the sum of five, giving us a synthesized assumption that is objective and certain, what Descartes sought all along.  As mentioned with Descartes, this strangely makes the ideas of logic and mathematics certainties, while the existence of coconuts or Paris, France are merely assumptions.

Transcendent & Transcendental

Essentially, Kant sought to rescue logic, including the Principle-of-Non-Contradiction, from Hume’s charge that all truth is assumption, and he hoped to do this by deducing the principles of logic without relying on assumptions based on experience.  This would reveal that logic was truly transcendental, necessary and universal to all experience, the frame through which we must grasp any idea or understanding.  While the word transcendent means exclusively removed from and supreme, like a sage who has transcended the world of desires, transcendental means consistently throughout and universal.  Wherever one is in the ocean, one would be wet as there is water throughout it.

Caspar Wanderer above the sea of fog (mountains hiker)

The American Transcendentalists, such as Emerson and Thoreau, argued that reality is an undivided whole beneath divisions imposed by the mind, a view they found in ancient Indian and Greek thought, and thus the oneness of things is not above and beyond, not transcendent, but within and throughout, transcendental, putting them in the pantheist company of Spinoza.  Unlike the Transcendentalists, Kant argued that the objective and subjective should be exclusively divided to prevent misunderstanding and maintain coherence, much as Locke had attempted to divide objective primary qualities from subjective secondary qualities.

Kant Hegel comic

Central to this for Kant was the exclusive definition and operation of the faculties of understanding and reasonVerständnis and Vernunft in the German.  Hegel took up Kant’s distinction between the faculties of understanding and reason, but influenced by fellow philosopher and friend Schelling, Hegel argued that understanding and reason must be synthesized and united, not exclusively divided.  Kant would have considered this the ultimate confusion, arguing in his first Critiquethat the mixing of understanding and reason is a major source of philosophical error as each has properly exclusive jobs to do.  For Hegel, Kant’s exclusive division between understanding and reason, as well as the division between the thing-in-itself and our experience of it, were failures of Kant’s inability to synthesize the whole with reason above and beyond the divisions of understanding.  While Kant thought that reason should ultimately serve understanding, maintaining exclusive distinctions, Hegel thought that reason should transcend while extending understanding, uniting all in the transcendental One, much like that of the American Transcendentalists.

apple on the tree

For Kant, experience requires two separate elements, sensation and understanding.  Sensation is the raw content and understanding is the conceptual form that makes sensation coherent.  Consider Berkeley’s example of an apple.  As we look at an apple, our experience is a union of the undefined sensation and the exclusive categories with which we understand the sensation such as red, solid, apple, and fruit.  Without both, there is no coherent experience of the apple.

Billiard Balls Pool

Kant argues that we can become confused, and believe that the category of ‘apple’ and ‘red’ exist in the world itself, are present in the thing-in-itself, but if we are being rational and exclusive we determine that the categories of understanding are not given in the world but conceptions of the mind, as Hume argued about cause and effect.  Thus, the thing-in-itself cannot be known, but the categories of understanding, when exclusive, noncontradictory and coherent, can be known with pure clarity.  Unlike Locke’s primary qualities, for Kant the objective is mental, not physical, like the forms of mathematics and logic.

Kant's categories

Understanding takes various sensations and synthesizes them into categories, while also exclusively dividing the categories from each other.  After we experience several objects, some of which are red, and some of which are apples, we form conceptions of redness and apples.  As the self experiences the world through its understanding, it finds itself with pre-existing fundamental categories, which Kant calls foundations (Grundsätzein the German, which also translates as ‘principles’).  Hegel was critical of Kant for pulling these categories out of nowhere without describing their development, but Kant believed that the origin of the foundational categories was beyond human comprehension.

bookcase painting

One of these foundations is the category of causation, which Hume considered to be an assumption learned through experience.  Kant, targeting Hume, argued that causation is a foundational category that is present in the mind before and apart from all experience, and that we find ourselves categorizing the world in terms of causation in a way that cannot be derived from experience.  Another foundational category of Kant’s is substance.  For Kant, the mind begins as an empty cabinet rather than a blank slate, with categorical compartments of causation and substance ready to be filled by experiences.  Thus, no matter what our individual experiences are, we will all categorize them in terms of causation and substance.

Aristotle proposed there are ten categories, ten sorts of things we can say other things are with words to make judgements, not categories installed in the ideal structure of our minds, listing them in his Categories as substance, quantity, quality, relations, space, time, position, state, action and passion.  Konigsberg and its university had a strong Aristotelian tradition long before Kant lived and taught there.  It was also a place where Locke was considerably influential with his talk of mental faculties, operations of mind, as if our minds are machines with different parts, or universities with different departments, that work in specific ways.  Kant turned from Empiricism and Locke to ideal categories reflected in our judgements of experiences, which uses Aristotle’s categories to rescue the certainty of knowledge from Hume’s skeptical ideas that all truth and causation are assumptions and imposed ideas.  Rather than oppose this point, Kant denies that all our imposed ideas come from experience, as some of our ideas, those Kant says are purest, come from our preformed categories, and we see this reflected in our experiences and judgements.  Aristotle, like Hume, says knowledge is a habit, a disposition that becomes fixed and quite permanent, though Aristotle says that disease and madness can rob us of knowledge and reason and would not agree that knowledge is simply human habit with human ideas imposed upon them, which he would consider too Heraclitean and relativistic. 

Kant, agreeing with Aristotle and Hume, says that knowledge is a habit that comes through experience, but unlike Aristotle Kant says knowledge is imposed by human ideas, but unlike Hume he doesn’t think we are a blank slate and get all our ideas from experience, as we do impose our human ideas on experience, which is all we can call knowledge, but it is not the world that is objective, but rather the structure of our minds that gives pure reason and grounded knowledge objectivity, imposing itself and reflecting itself in our pure ideas and judgements what we think that we reflect isn’t only sometimes the case, in this or that experience, but must always be the case, what must be in this, that or any experience.  In Kant’s Critique of Pure Reason, he says we can see the twelve categories reflected in the four forms of pure judgement, which each have three moments, and this is because each of these twelve pure judgement moments can be abstracted and freed from all content.  He provides no explanation other than the systematic presentation of the four as to how they can have form, or be interrelated, when freed from all content.  Kant’s categories overlap with Aristotle’s, but they also overlap with the four classes of judgement of Aristotle from his On Interpretation, which are listed as four classes of two poles of judgement, to which Kant simply added a third element, the union of the first two in his reasonings.

foucault library knowledge

Reason serves as a higher level of understanding, just as understanding serves as a higher level of sensation.  Just as understanding joins and separates sensations, reason joins and separates understandings.  Judgement performs both of these activities, dividing sensations into groups for understanding and dividing understandings into groups for reason.  Reason infers similarities and differences of understandings, forming ideas.  Ideas, such as freedom and beauty, central examples used by Kant and fleshed out in the second and third Critiques, are not directly experienced in the world but are formed through inferences drawn from the understanding.

Kant Lecturing

For Kant, it is crucial to keep reason separate from understanding.  Reason is transcendent, beyond sensations and understandings, whereas understanding is transcendental, throughout sensations and reasonings.  Reason is separate from the sensible world, and thus free to form ideas.  This corresponds to Descartes’ dualism, dividing the determined body from the free mind, except for Kant both understanding and reason are mental.  While the understanding is passive, categorizing sensation as it happens, reason is active, producing ideas as it sees fit.  Experience is determined by the understanding, but ideas are formed from the free use of reason within the imagination, separate from, though derived from, experience and understanding.

Kant side view

For Kant, reason is free to wander, taking a wider view, forming abstract ideas and speculating about what might be, however it may not contradict the understanding.  For Hegel, reason’s job is to extend but also contradict understanding, to contradict accepted dogmas with opposite points of view and force progressively greater synthesis beyond exclusive boundaries.  For Kant, contradiction with the understanding results in incoherence, an improper mixing of understanding and reason, not a greater synthesis of knowledge.  For Hegel, understanding is extended by contradiction, transforming the incoherent into the coherent.  Both believe that reason works through dialectic, by weighing both sides of a potential judgement and then extending the understanding, arriving at a greater understanding than before.  Should reason never result in contradiction, or should it contradict itself and then overcome the contradiction?  It depends on whether one accepts or opposes the Principle of Non-Contradiction.

chimp thinking

For Kant, understanding has jurisdiction over things, whereas reason has jurisdiction over ideas.  In this sense, while the understanding categorizes things, such that we experience things as substances that cause and are affected, our ideas of substance and causation are part of our free, abstract reasoning, which judges the categories of the understanding to produce abstract ideas.  This would mean that ‘substance’, ‘nature’ and ‘beauty’ are ideas, not things, produced by reason, not experienced in the world.

Work is Freedom Auschwitz

In both epistemology and ethics, Kant argues that we are free, but we are merely free to find the singular, necessary and objective truth or to be mistaken and confused depending on whether we are being objective and rational.  Bill Hicks, the comedian quoted earlier, had a bit mocking American television, shouting, “You are free to do as we tell you!”.  This is disturbingly similar to the Nazis posting, “Work is Freedom” above the entrances to the concentration camp at Auschwitz, an inspiration to George Orwell as he wrote doublespeak slogans for the tyrannical Big Brother government of his novel 1984, such as “War is Peace”.

Island in the sea

Kant used the metaphor of an island in a stormy sea to illustrate the rational mind amidst the flux of the sensual world, objective and rational in the sea of the uncertain.  Schopenhauer, a Kantian, used a similar metaphor of a ship on a stormy sea, more skeptical than Kant as a boat is not fastened down but drifts with the current of the passions.  While the understanding is passive, and can only judge sensations as they happen, reason is free to speculate as to what could, or should happen.  Hume famously argued that one cannot derive an ‘ought’ from an ‘is’, that we cannot know what should happen merely based on what is happening.  Kant meets Hume halfway. ‘Ought’ and ‘is’ are two separate things, as Hume argued, but for Kant reason can derive what objectively ought to be.  Kant’s central example of morality, “Do not lie”, is a necessary conclusion that reason arrives at when it properly surveys the understanding and speculates with ideas.  The conclusion is seen by reason to be universal, necessary, and objective.  Thus, while reason cannot tell us whether we will lie next Tuesday, we can say that it would be objectively wrong to do so.

Fox resting

Nietzsche said Kant was like a fox who admirably broke out of his cage, only to lose his way and wander back into it.  Nietzsche disregards all claims to objective truth as mere human interpretations, and so he admires Kant for arguing that reason is free to do as it likes but finds him foolish for arguing that reason must conform to the rational, objective understanding or be wrong.  While Kant had hoped to justify and preserve metaphysics, his skepticism towards our knowing the thing-in-itself ultimately lead to the downfall of metaphysics, heralded by Nietzsche.

Scottish Bagpipes in Battle

Realists, like the Scottish Realists who had an impact on Analytic philosophy, thought that Kant had gone too far in agreeing with the skepticism of Hume.  Similar to Johnson kicking the rock, Realists argue that it is ridiculous to speak of causation and substance as assumptions or categories of the mind, as they are clear and objectively present in the world.  The question is, when is it worthwhile to question our conceptions of causes and substances?