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A Resource Guide for Philosophy Students

Created by Jennifer Leslie Torgerson, MA

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School of Athens


Immanuel Kant

1724 - 1804




Frederick Copleston, S.J., A History of Philosophy:Book Two.(New York, NY:Doubleday, 1985 [1944]).


Immanuel Kant.Critique of Pure Reason. J. M. D. Meiklejohn, editor. (New York, NY:Prometheus Press, 1990).


________.Grounding for the Metaphysics of Morals and On a Supposed Right to Lie because of Philanthropic Concerns, 3rd Edition; James W. Ellington, Translator.(Indianapolis, IN:Hackett Publishing, 1993 [1981]).


________.†† Grounding for the Metaphysics of Morals. James W. Ellington, Editor.(Indianapolis, IN:Hackett Publishing Company, 1980).

________.The Critique of Judgement.(Oxford, UK:Clarendon Press, 1991 [1952] ).

________.The One Possible Basis for a Demonstration of the Existence of God. (Lincoln, NE:University of Nebraska Press, 1979).

Smith, and Grene.Philosophers Speak For Themselves.(Chicago, IL:The University of Chicago Press, 1957).

W. T. Jones.†† A History of Western Philosophy:Kant and the Nineteenth Century, 2nd Edition.(San Diego, CA:Harcourt Brace, 1980 [1952]).



The works of Kant

On Fire (1755).

General Natural History and Theory of the Heavens (1755).

A New Explanation of the First Principles of Metaphysical Knowledge (1755).

The False Subtlety of the Four Syllogistic Figures (1762).

The Only Possible Ground for a Demonstration of Godís Existence (1762).

Enquiry into the Distinctness of the Principles of Natural Theory and Morals (1764).

Observations on the Feeling of the Beautiful and Sublime (1764).

Dreams of a Ghost-seer, explained by Dreams of Metaphysics (1766).

The Bounds of Sensibility and Reason (1771).

The Critique of Pure Reason (1781). Second edition published in 1787.

Prolegomena to any Future Metaphysics (1783).


General History form a Cosmopolitan Point of View (1784).


Fundamental Principles of the Metaphysics of Morals (1785).


On Volcanoes in the Moon (1785).


Metaphysical First Principles of Natural Science (1786).


Critique of Practical Reason (1788).


Critique of Judgment (1790).


On the Failure of all Philosophical Attempts at a Theodicy (1791).


Religion with the Bounds of Reason Alone (1793).


On Perpetual Peace (1795).


The Metaphysics of Morals (1797). Formed from Elements of the Theory of Right and the Metaphysical Elements of the Theory of Virtue.


Opus Postumum


Kant and the A Priori

Immanuel Kant (1724- 1804), a Prussian philosopher, who labeled his own position "transcendental" or "critical" idealism.

a little historical intro.

The Age of Reason and the mood of the Enlightenment:

The eighteenth-century philosophers were persuaded that they lived in the best of all possible worlds. Because nature seemed to beneficent- "Whatever is, is right." - and because people seem rational, they conclude that progress was inevitable. But this optimism suffered a series of severe blows. The French Revolution in 1789, which was supposed to mark the over throw of tyranny only ushered in a more formidable tyranny- Napoleon. The Industrial Revolution, instead of bringing peace and plenty, resulted in urban overcrowding and misery. And Hume's use of Locke's empirical criterion of meaning proved to have undermined- even more than Hume himself realized- both the concept of nature and the concept of reason. As a result a counter movement began to emerge- a movement hostile to science, skeptical of progress, opposed to prosperity, and increasingly alienated from the long-dominant values of rationality, self-consciousness, objectivity, and detachment.

Kant recognized the destructive potential of Hume's critique; one of the main drives that animated his thought was the desire to answer Hume's criticisms of the claims of science and to show that an a priori knowledge of nature is possible. A second main drive of his philosophy, however, was to limit scientific knowledge in order to make a place for a feeling, for what he called "faith". Both of these aims were accomplished in a single stroke by what Kant called his "Copernican revolution" in the theory of knowledge. Abandoning the traditional view that minds are the essentially passive contemplators of individually existing objects, Kant held that objects are the constructs in which the activity of minds plays an essential part.

Distinction between form and content:

There is a distinction to be made between the form of a judgment and its content. All judgments fall into two classes depending on their form: (1) they assert that either that something has such-and-such a property (This rose is red) or, (2) they assert that something is the cause of something else, or that something has such-and- such a degree of quality and so on. There is a kind of putting together that consists in attribution; there is another kind of putting together that consists in causation.

The problem of pure reason:

In Kant's questions is "How are synthetic a priori judgements possible?" This is according to Kant the "general problem of pure reason."

A judgment is a movement of thought in which two items are brought together and combined. We judge whenever we say: "This house is large." or "the interior angles of a triangle equal two right angles." The mind brings together the terms in a judgment because it detects a connection between them. It is this connection that is the warrant, or basis, of the judgment.

"This house is large" is an a posteriori or empirical judgment.

"The interior angles of a triangle equal two right angles" is an a priori, or "independent of experience".

Kant explains: "Experience teaches us that a thing is so and so, but not that it cannot be otherwise. First, then, if we have a proposition which is being thought of as necessary, [...] it is an a priori judgement [...] Secondly [..] if, then, a judgement is thought [...] in such manner that no exception is allowed as possible, it is not derived from experience, but is valid absolutely a priori. [...] Necessity and strict universality are thus a criteria of a priori knowledge, and are inseparable from each other." Critique of Pure Reason

analytic: propositions that are true by definition (tautological) and necessary.

synthetic: propositions that are not true by definition and are contingent.

a priori: the truth value of these propositions are known independent of experience.

a posteriori: the truth value of these propositions are dependent upon experience.

noumena: things-in-themselves (or beyond appearance). The term literally means the thing that appears, but this is beyond our perception.

phenomena: that which appears, or better, the appearance of a thing. We experience the appearance, but not the thing that appears.

transcendental deduction: to go beyond (transcend) direct observation to discover necessary conditions. Deduction is a form of logical argument in which the conclusion necessarily follows from the premise(s) and hence the conclusion can be held with certainty.

transcendental idealism: the view that what we know of reality is immaterial and consists of understanding phenomena or perceptions about the phenomena. That which causes the phenomena (the noumena) is beyond our experience and understanding.


Hume thought that all analytic propositions were a priori and that all synthetic propositions are a posteriori. Kant does not agree. Kant claims that all analytic propositions are a priori but not vice versa and that all a posteriori propositions are synthetic but not vice versa. This means that there are synthetic a priori propositions.


a posteriori

a priori


1. analytical a posteriori

2. analytical a priori


3. synthetical a posteriori

4. syntheticial a priori


a posteriori

a priori


1. null

2. warranted by law of contradiction


3. warranted by  experience

4. ?

1. There can be no analytical a posteriori judgments, because all analytical statements are universal and necessary.

2. Since a flower is part of the definition of a rose, we contradict ourselves if we assert that a rose is not a flower.

3. Such judgments are warranted by experience.

4. But what about synthetical a priori judgments, how are they possible? They are not warranted by experience, nor by the law of contradiction, but by an organizing principle of the mind (or the irremovable goggles).

(a) synthetical a priori judgments do apply to mathematics (arithmetic and geometry in particular), because mathematics (as Hume also thought) is synthetical (Is 5 + 7 = 12 identical to 6 + 6 = 12? no.), but Kant also thought that mathematical judgments are universal and necessary. Hence they are synthetical a priori judgments. Typical such judgments would be seen as analytical and a priori.

(b) Kant also agreed with Hume that synthetical a priori judgments could not be applied to metaphysics, but asking such question points to the fact that reason has a 'regulative' use.

(c) But synthetical a priori judgments can be applied to physics, and other natural sciences. Every event has a cause can be known as a synthetical a priori judgment.

Kant says that the mind has three faculties:

(1) intuition (perception),

(2) understanding (of perceptions),

and (3) reason.

Reason is about pure concepts that are uncontaminated by the senses.

Kant uses his transcendental deduction to answer the question: How is perception possible? Kant would not ask: "What is perception?" He wants to know how perception is possible, since this is a commonsense question that is based on the commonsense view that we do perceive the world.

In order to understand our perceptions some conditions must hold. It is impossible to explain reality using sense data as the sole source of our perceptions and ideas. The sense data is unorganized by itself. Thus concepts are not deduced from reality, but in fact that mind brings them to reality. We each have a set of irremovable goggles out of which we view the world. We need to transcend our experience and get behind it to discover the necessary conditions needed for understanding. There must be a necessary structure of the mind (the irremovable goggles) that organizes our experiences. These are like rules (i.e. of a game) used to organize the sense data and contain: space, time, substantiality, and causality. Substantiality is best described by the table of categories and it is not equivalent to acknowledging the existence of Substance since such would be part of the unexperienced and noumenal realm. The Table of Categories includes: (1) quantity (universal, particular, and singular); (2) Quality (affirmative, negative, infinite); (3) Relation (categorical, hypothetical, disjunctive); (4) Modality (problematic, assertoric, apodictic). Problematic propositions are disputable and not demonstrable. Assertoric propositions are affirmed without proof. Apodictic propositions are clearly demonstrable and indisputable. For more about quantity, quality and relation, please take one of my Logic courses, or check out my Logic Topics page, which contains definitions of all of the terms in those categories.

You can believe in God, soul, immortality, justice, freedom, but you cannot claim you know these via perception, understanding of perception, or reason. There are NO synthetical a priori foundations for such concepts. These terms are NOT metaphysical necessities, but they can be seen as practical necessities.


Kant rejects the correspondence theory of truth due to his transcendentalism. We are unable to match our statements to some external reality that is independent of our experience. What lies behind our perceptions or the phenomenal experience is noumenal and ineffable. Correspondence theory of truth is the view that true ideas match their ideate (or objects). Kant anticipates the need for a new theory of truth. He uses the coherence theory of truth, since Kant holds that statements or beliefs are true only if they tie in with other statements or beliefs (using the irremovable goggles). He uses something like the pragmatic theory of truth. Kant holds that statements or beliefs are true only if they work (or as James puts it, have cash-value). Kant uses something like the semantic theory of truth since true statements or beliefs follow the rules of language which set up a correspondence between certain statements and "the facts" our language picks our in the world.

Critique of Kant:

Kant's positions are gained from using a priori reasoning, and empiricists may find this foundation merely tautological and not able to express anything about the world of experience.

This certainty gained by combining a priori with synthetical knowledge has had a cost: namely the knowledge of that which transcends the phenomenal world (things as they appear), the noumenal (things-in-themselves), which includes God. But this is because this type of reasoning is of the theoretical type. Kant is well aware of the loss. This is the main point to the Critique of Pure Reason. Reason is about pure concepts uncontaminated by the senses (such as God and soul). There are no synthetic a priori foundations for such concepts. We can only understand concepts gained from our perceptions which we get via intuition.

Practical reason will provide a means of "knowing" through the moral argument for the possibility of existence of God. Kant rejects the traditional arguments for the existence of God since they claim to be able to demonstrate existence by necessity and use existence as a real predicate. Kant is only willing to argue for the possibility of the existence of God.

Kant's Moral argument "for the possibility of the existence of God"

The moral argument for the existence of God postulates that the existence of God is a necessary condition for the Summum Bonum (Highest Good). The pursuit of the highest good (summum bonum) demonstrates that the existence of the original highest good (or the existence of God) is possible. The author of the highest good is God.

Remember that Kant does not pretend to be able to demonstrate the existence of God.  Kant is not using existence as a predicate.  This argument is based in practical, not pure, reason.

The critique to this argument is that the mere postulating of the existence of God as a necessary condition of the summum bonum does not demonstrate that God necessarily exists. The highest good may be attainable without having been created by God. Knowledge of what is good does not necessarily depend upon a supernatural deity.   

Kant's categorical imperative as an example of deontological ethics

Kant said that all imperatives are either categorical or hypothetical. Kant never claimed to discover the categorical imperative. It is a working criterion supposedly employed by any rational agent as a guide for making his or her own judgments but without his or her being necessarily able to formulate it or make it explicit. Kant has five different formulations of this moral law in his Grounding for the Metaphysics of Morals (1785).

categorical imperative: is the necessary and absolute moral law believed to be the ultimate rational foundation for all moral conduct. "So act that you can will the maxim (principle) of your action to be an universal law binding upon the will of every other rational person." Categorical imperatives are absolutely binding.

Whatever you claim to be good or right should be good or right for everyone. One must obey the categorical imperative without regard to the consequences of the action. It is one's duty to follow the categorical imperative. Categorical means obligatory.

(1) The first formulation of the categorical imperative in the Grounding is : that one should act only on that maxim that can be at the same time willed to become universal law [of nature].

(2) The second formulation of the categorical imperative in the Grounding is : that one should always act in such a way that humanity either in oneself or in others is always treated as an end itself and never merely as a means. If a person is treated as nothing more than a means, then (s)he is treated as nothing more than a thing without purposes of his or her own rather than a self-determining agent.

Really (1) and (2) are equivalent. According to the formula of universal law, any violation of the formula of the end in itself must be wrong; i.e. when someone is treated as a mere means, his purposes are regarded as not counting; when the maxim of such treatment is universalized, the agent of such treatment must be willing to be so treated in turn. But here is a contradiction, for no one wants his purposes to count for nothing. The two formulations simply imply one another, and therefore must be equivalent.

hypothetical imperative: command one to do X only if you wanted Y. This conditional statement is not absolutely binding. Hypothetical means 'optional', or contingent.






Suicide is ALWAYS wrong

Perfect your talents (never be lazy)


Lying is ALWAYS wrong

ALWAYS be benevolent to others

Critiques of Kantian ethics:

(1) Can reason alone be trusted to discover the right and the good? Can moral law be found a priori?

(2) What happens when two moral laws conflict? It would be impossible to know how to act in that situation.

(3) Some rules may have exceptions, but the absolutist would claim that you should always follow the rule no matter what the consequences may be.

(4) Is there moral law? Some believe in a subjective, or relative ethic.


Actions are right because of some objectively existing quality in them, which when experienced, makes them desirable. Therefore these values or laws are grounded in a reality outside humanity. These laws are universally binding for all and are eternally true. These laws can be discovered through the use of reason. Because of the emphasis upon following the eternally true laws, objective ethics are deontological in nature. Objectivism is the opposite of relativism, or a subjective ethic.

examples of objective ethics:

(1) Kant's categorical imperative

(2) The philosophy behind the ethic of the Constitution is objective. Jefferson stated the basis of the objective ethic in his Declaration of Independence:

"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, among them these are Life, Liberty, and the pursuit of Happiness." This is not a right to do anything, but only those rights which have been established by our Creator.

We saw that this passage was lifted directly from Locke's Second Treatise of Government, but Locke said "... life, liberty and property."

(3) Plato's theory of Ideal Forms is another example of an objective ethic. The true absolute reality is in the realm of perfect, independently existing, unchanging, timeless, Ideal Forms. The Good can be known through the light of reason. (Republic BK 4).

subjective ethics: The theory that ethical judgments such as "good" means "I approve" of certain actions. Moral values are based on feelings, thoughts, and desires which have no objective reference in the world.

examples: (1) cultural relativism   (2) relativism