Kant’s Ethics – Summary

(This summary was produced for my introductory classes to Kant – references to this text should appear as Sjöstedt-H, P. (2007) Kant – Deontology, philosopher.eu/texts/kants-ethics-summary)


Kant – Deontology

©Peter Sjöstedt-Hughes 2007


General Introduction to Kant 


–       Immanuel Kant (1724–1804).

–       As we shall find, Kant argues that morality is deontological. ‘Deon’ is Greek for duty. This states that we do moral acts because they are good-in-themselves – not because they cause good consequences, nor because of emotions (either prior to or after the act).

  • For example, we ought to avoid murdering someone, not because we may end up in prison, nor because we may feel regret or remorse, but because it is a wrong thing to do per se (in itself). This even applies to murdering a person who may go on to kill hundreds thereafter.
  • Consequentialism, usually as utilitarianism (but also as ethical egoism, hedonism), states that an action is good if it causes the most pleasure and the least pain. So, in some cases, murder would be morally acceptable. Its main proponents are Jeremy Bentham and John Stuart Mill.




–       Some believe that the motivation of our actions is merely the seeking of pleasure (and avoidance of pain).

–       Against this belief, Kant argues that if pleasure were the only thing that motivated our actions, then we would only have instinct to guide us, as instinct suffices for obtaining pleasure (such as animals). (From Kant’s ‘Groundwork of a Metaphysics of Morals’)

–       However, humans have reason above instinct, and this means that our motivations go beyond mere pleasure.

–       So the function of reason is not pleasure or happiness, but to produce a will that is good in itself (not good for something else, such as happiness).

–       A good will is manifested in acting for the sake of duty.

–       One’s duty is to follow the Categorical Imperative as not doing so would mean that one acted for one’s own pleasure. This would mean that one is misusing reason – being irrational.

–       One should therefore follow one’s duty even if it goes against one’s (pleasurable) desires and certainly not for the sake of desires (this includes ‘feel-good’ emotions like sympathy or compassion).

–       If a person does a good deed at a time when he is fully occupied with his own troubles, it shows that he does it out of duty, not natural inclinations.


Categorical Imperative and Maxims


–       A maxim is a principle upon which we act.

–       A maxim may be good or bad. It is usually not put into words, but this can be done. For example, “I will always try to work hard when I have little money”.

–       A subjective maxim is one that is good for the person. (~a ‘hypothetical imperative’)

  • E.g. “I ought to practise the guitar if I want to become a professional player.”

–       An objective maxim is one which every rational person would act upon if reason had full control of his or her actions (not just desire, greed, etc.–subjective) (‘categorical imperative’).

–       Duty is an objective maxim ‘irrespective of all objects of desire’.

–       A good person adopts or rejects a subjective maxim for any action according to whether or not it harmonises with an objective maxim of doing duty for duty’s sake (not for a personal sake).

–       Kant goes on to say that duty is the necessity to act out of reverence for a universal law.

–       An objective maxim is a universal law – our reverence for it comes from our general reverence for rationality.

–       Kant calls the objective maxim, the Categorical Imperative:

  • I ought never to act except in such a way that I can also will that my maxim should become a universal law’.
    • This is the 1st formulation:

The Formula of Universalisability (or, The Formula of Universal Law).


The Formula of the End in Itself: This other important formulation (derived from the first) is:

–       Act in such a way that you always treat humanity, whether in your own person or in the person of any other, never simply as a means, but always at the same time as an end.

  • People are ends-in-themselves (as their goodwill is unconditioned – all other ends are conditioned/hypothetical, and thus cannot be the basis for morality). I.e. without objective ends, there can be no morality.
  • We have a (-ve) duty not to use ourselves or others as means to satisfy our inclinations.
  • We have a lesser (+ve) duty seek our own perfection and the happiness of others.
  • This is especially opposed to consequentialism.


The Formula of the Law of Nature:

  • Act as if the maxim of your action were to become through your will a universal law of nature.
  • I.e. we must ask whether, if our subjective maxim (i.e. thought for an action) were universally adopted, would it further a systematic harmony of purposes in the individual and in the human race. If not, the action would be immoral.
    • This formulation depends on a teleological view of nature – i.e. that everything has a purpose/telos. This is rejected by,say, post-Darwinists, for a mechanistic view of nature.
    • This formulation is used by Kant as an argument as to why suicide is immoral: one would will that self-preservation were a law of nature (a purpose of life), not therefore its opposite, suicide.
    • (This Law was later merged into the first.)


The Formula of Autonomy:

  • So act that your will can regard itself at the same time as making universal law through its maxim.
    • This is merely a combination of the formulae of Universalisability and End-in-Itself, highlighting the fact that ‘it is precisely the fitness of his maxims to make universal law that marks him out as an end-in-himself’ [p.83].
    • Man is both the creator (as a rational being) and an essential ground (as an end) of morality: this emphasises man’s supreme value.
      • I.e. this is a formulation for self-respect and respect for mankind.
      • (It also emphasises the fact that categorical imperatives exclude interest (subjective desires).)


The Formula of Kingdom-of-Ends:

  • So act as if you were through your maxims a law-making member of a kingdom of ends.
    • ‘Kingdom of ends’ =  a commonwealth of people subject to universal laws with all members constituted as having intrinsic worth/dignity as ends-in-themselves.
    • Consider yourself both law-maker and law-abider so to become moral.




–       There are Hypothetical Imperatives and the Categorical Imperative


–       Hypothetical Imperatives are conditioned by an end.

–       Hypothetical Imperatives’ good is the means to the end.

  • E.g. “I ought to study hard, if I want to pass my exams.”
  • End: wanting to pass. Means: studying hard. Good: studying hard, thus as well.
    • I.e. studying hard is good.

–       Categorical Imperatives are not conditioned – they have no if-clause.

  • E.g. “I ought to be honest.” (no “if”)
  • They are not conditioned (unconditional) because if they did have a condition they would not be performed from a good will but from a subjective desire and would thus not be moral (but selfish).
    • I.e. for morality to be possible we must presume that the maxim (C.I.) upon which they are performed be unconditional.
    • If there were a condition, an end, the action would not be moral but selfish. E.g. “I ought to save his life, if I wish not to feel guilty forever after” is not a moral maxim but a hypothetical imperative.
    • Most ‘oughts’ (if not all) in language are hypothetical (e.g. “I ought to diet.”).


Free Will


–       For Kant, morality is only possible if free will exists.

–       If free will did not exist, then we would not be free to choose which action to take. In which case we could not be held responsible (in a positive or negative way) for our actions (we would be like programmed robots).

–       Free will is free intention.

  • This is one aspect of what decides whether an action is moral:
    • A shopkeeper gives back the right change because he thinks that is his duty. He is moral
    • A shopkeeper gives back the right change because he thinks the person will complain if he doesn’t. This is not moral.
    • This shows that mere consequences (as in utilitarianism) cannot really explain the morality of an action.

–       But how can free will exist if everything is caused by previous events (determinism)?

  • Kant divides the universe into phenomena and noumena.
  • Phenomena are the everyday physical things we perceive.
    • We actually create the phenomenal world by imposing concepts like space, time and causality onto the world in order to understand it.

–       Noumena are the world behind appearances and our concepts (things-in-themselves); how things are beyond our perception (i.e. beyond even time, space and causality).

–       Free will, Kant writes, actually lies in the noumenal world and is therefore not affected by prior causes, as causes only exist in the phenomenal world.

–       So free will can exist and thus can morality.


God and Morality


–       Although morality leads to religion (we come to realise that God, immortality and free will are the three postulates of morality), morality cannot be derived from religion.

–       We must reject the theological principle that to be moral is to obey the will of god, because we can only know that ‘God is good’ if we already know what goodness is, but if we know that, we cannot need god as the basis of knowing what goodness is!

–       (See my notes on ‘Kant’s Moral Argument for God.)


Synthetic a priori


–       Furthermore, Categorical Imperatives are synthetic a priori propositions.

  • They are a priori, as morality must come prior to experience.
    • We cannot derive morality from experience (a posteriori) because how then would we be able to recognize a moral act as being moral if there were not something already within us (a priori: before experience) that recognized an act as moral.
    • Thus Kant’s ethics is necessarily prescriptive, not descriptive.
  • They are synthetic because the predicate is not contained within the subject (as in analytic propositions).
  • E.g. Analytic a priori: “A square has four sides.” (i.e. true by definition.)
  • Synthetic a posteriori: “All cars have four wheels.” (predicate, 4 wheels, not contained in subject, all cars).
  • Synthetic a priori: “12 = 5 + 7”. ‘5+7’ (predicate) not contained in idea of ‘12’ – thus synthetic. But neither is this proposition true through experience (a posteriori), so it is also a priori.
  • Consequently a Categorical Imperative is synthetic a priori: the predicate is not contained within the subject, but neither can it be derived from experience.
    • E.g. “I ought not to lie.”
    • Subject, ‘I’, the rational agent, does not contain the predicate ‘ought not to lie’ (maxim). Thus, synthetic.
    • But it is also a priori because the maxim cannot be derived a posteriori/from experience.

– As moral judgements are a priori, it means they must come from within. They must be intentions.


Immorality as Irrationality


–       An immoral act for Kant is one which, if we universalised it with the categorical imperative, will make the act impossible.

–       It will make it impossible as the universalising will render the action a contradiction.

–       For example, “I shall steal food if I cannot afford it.”

  • If universalised this would mean that all people would steal food if they could not afford the food.
  • If everyone did that, it would mean that putting a price on food would become pointless. Therefore, food would be free. If food were free, the idea of ‘stealing’ makes no sense.
  • Therefore universaling the subjective maxim would lead to a contradiction.
    • To universalise stealing is to make stealing a redundant term.
  • This contradiction indicates that an act (or maxim) is immoral.

–       This is why immorality is irrationality (contradictions are irrational).

–       So, for Kant, a moral wrong is a logical wrong (like 2+2 = 5).


–       The above is known as a Contradiction of Conception (the concept contradicts itself), and it applies especially to the Formula of Universalisability.

–       For Kant however, there are two other forms which inform a moral decision:

  • Contradiction of the Will
    • When you would not want the maxim to become universal.
    • This applies especially to the Formula of Kingdom-of-Ends
  • Contradiction of Purpose/Telos
    • When the action would contradict the natural purposes (final causes) found in nature.
      • When the action would contradict the natural purposes (final causes) found in nature.
      • This applies especially to the Formula of the Law of Nature.

An example: promises

–       Suppose I had a subjective maxim that read, “I shall break promises that I find hard to keep.”

–       If I apply the categorical Imperative, if I universalise, it would mean that I would want all difficult promises to be broken.

–       But if promises are to be broken by all, a promise no longer is a promise: it means nothing, it cannot be trusted.

–       As a promise is an oath of trust, and it is untrustworthy, the term is made redundant through contradiction (A = not-A).

–       Therefore breaking a promise is immoral.


Another example: Stealing

–       Suppose I say, “I shall steal if I can.”

–       If we universalise this, it means that everyone would steal if they could.

–       This means that there would be no point in putting a price on anything.

–       That means property would not be for sale.

–       That means the concept ‘property’ would not be possible

–       Therefore the concept of stealing would not be possible.


Perfect & Imperfect Duties


–       A Perfect Duty is an imperative that one must do at all costs (e.g. do not murder, steal, break promises, etc.)

–       An Imperfect Duty is an act that one ought to pursue if one can. For example, that one ought to develop one’s talents, be courteous, encourage others, give to charity, etc.

  • Breaking an imperfect duty will not lead to contradiction if universalised.


Schopenhauer’s Criticism of Kant’s Deontology


–    For Kant, normativity (prescriptive ethics) is simply assumed and never proved.

–     “Kant’s first false statement lies in his concept of ethics itself, a concept which we find articulated most clearly [in Metaphysics of Morals, p62]: ‘In a practical philosophy it is not a concern to indicate reasons for what happens, but laws for what ought to happen, even if it never happens.’ – This is already a decided petitio principii [question begging]. Who told you that there are laws to which we ought to subject our actions? Who told you that something ought to happen that never happens? – What justifies your assuming this beforehand and thereupon immediately to press upon us an ethics in a legislative-imperative form as the only possible sort?” (On the Basis of Morals, §4)

–     i.e. Kant assumes that morality must be prescriptive and thereafter seeks the conditions for this prescriptivity. He thus assumes what he seeks to prove: moral laws.

–      Furthermore, Schopenhauer identifies the origin of this unproved assumption as Judeo-Christian:

–    “I recognise no other source than the Decalogue [Ten Commandments, Exodus. 20]. In general, in the centuries of Christianity, philosophical ethics has unconsciously taken its form from the theological. Since this ethics is now essentially dictatorial, the philosophical too, has appeared in the form of prescription and the doctrine of duty in all innocence and without suspecting that for this, first a further authority is necessary [God]. Instead, it supposes that this is its own and natural form.” (ibid.)


–     Anticipating Nietzsche, Schopenhauer clearly considers Kant’s allegedly rational morality to have religious groundings after all, despite Kant’s attempt to unfetter it.

–    The ultimate justification for such normativity is God. And so if ‘God is dead’, then this imperative form of morality is unjustified.

–   Nietzsche’s thought is further revealed as Schopenhauerian when we read in the same essay, in response to a Kantian imperative, “What slavish morals! … slavish fear of the gods” (ibid.)

–    Schopenhauer also criticises Kant by arguing that an unconditioned ought (an ought with no if-clause) is a contradiction in terms.

–                Every ought only has meaning ultimately in relation to threatened punishment or promised reward.

–               i.e. “I ought to do x, if I want (reward or no punishment)”.

–               Hence, all ought’s are hypothetical (with Hume) by definition.

–                Schopenhauer states that in fact this reward does sneak in the ‘obscure’ chapters on the postulates of morality: happiness &


–                That which motivates a person to seek a rationally-grounded basis of morality is a non-rational desire/incentive.

– Which for Kant was to emasculate religious (& political) authority.

–               Reason alone, Schopenhauer states, cannot motivate to action; reason is employed by desire/the will.

–               Therefore Kant’s deontology cannot be based on reason but ultimately desire. Kant therefore fails his project.


–    Free Will is impossible (see his superb essay on the subject). Therefore instead of postulating it as necessary for morality, Kant should rather reject (normative) morality, as its condition (freedom) is impossible.


a.      Schopenhauer wrote an essay on the freedom of the will. To quote Einstein again, “I do not believe in free will. Schopenhauer’s words: ‘Man can do what he wants, but he cannot will what he wants’ accompany me in all situations throughout my life and reconcile me with the actions of others, even if they are rather painful to me. This awareness of the lack of free will keeps me from taking myself and my fellow men too seriously as acting and deciding individuals, and from losing my temper.”


–    Briefly, Schopenhauer argues against free will thus:

–    One cannot consciously determine what one wishes.

–     Imagining an action is not the cause of an action.

–    The purpose of reason is to offer motives to the will, Reason itself does not cause actions. It is advisor, not executor.


©Peter Sjöstedt-H

Further Kantian analysis is found in my book, Noumenautics.

(“Kant’s Joke – Kant wanted to prove, in a way that would dumfound the common man, that the common man was right: that was the secret joke of his soul. He wrote against the scholars in support of popular prejudice, but for scholars and not for the people.” – Nietzsche, Joyous Science, §193)

immanuel kant deontology ethics morality categorical imperative