This is not originally my question but someone deleted their question while I was typing an answer to it. Consequently, I'm reposting the question and then my answer -- n.b., I've changed the title slightly to correct for what I'm guessing he deleted the question for.

I'm studying existentialism at the moment and Sartre's explanation of existentialist ethics is as follows:

Thus, the first effect of existentialism is that it puts every man in possession of himself as he is, and places the entire responsibility for his existence squarely upon his own shoulders. And, when we say that man is responsible for himself, we do not mean that he is responsible only for his own individuality, but that he is responsible for all men.


Our responsibility is thus much greater than we had supposed, for it concerns mankind as a whole. (Existentialism and Humanism).

This sounds similar to Kant's categorical imperative - the idea that when making a decision, we should imagine making a universal law for all of mankind.

So, is this Sartre borrowing from Kant?

  • @n-soong here's a rewording of your question with an answer.
    – virmaior
    Commented Apr 3, 2014 at 7:16
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    virmaior you're a funny man. Good idea. This has the advantage that if you have a clarificatory question, you can get an immediate response. Commented Apr 3, 2014 at 8:32
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    @HunanRostomyan oddly this is actually built is an option by design. I was literally in the middle of typing it while he was arguing with someone in the comments and then deleted it. Not letting good work go to waste.
    – virmaior
    Commented Apr 3, 2014 at 9:14
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    The answer is worth the question. Commented Jun 17, 2014 at 12:15

2 Answers 2


In some respects, you could say that Sartre is "borrowing from Kant." It will greatly depend on what you mean by borrowing. Iphigenie's comments are highlighting the differences, and those are definitely worth pointing out but a type of "rationalist" heritage is worth bringing up.

What I would say is the common thread is an emphasis on "autonomy" and a belief that human beings possess a type of unrestricted autonomy in reference to their choices. Neither thinker is ultimately naive enough to say that we always have this, but both theories have been accused of separating us from bodily concerns under the belief that we can make choices regardless of circumstances. In the simplest terms, both have a very high belief in our autonomy and that we have a free rational will.

At the same time, there are some crucial differences about how our rationality works for both thinkers. A core feature of Kant's account of morality and his account of rationality is that they have universality. In moral theory, this means that the moral rules apply to everyone insofar as they are humans at all. (Kant's particular method of how he gets there for morality is both highly contested and largely believed to have failed). But the key is that for Kant, reason works the same in every person and will logically lead them to the same conclusions. This is evident if you consider both the phenomenological / noumenal split and the categories of the understanding (the transcendental unity of apperception). This has led to the accusation that Kant's philosophy is a "German sausage machine" because whatever comes in gets pumped out the same. Thus, the CI is the same for all subjects who are rational. In a sense rationality predominates autonomy. (There's a lot more complexity if we are start looking at imperfect duties...)

For Sartre, our autonomy is our defining feature. In his view, we do seem to have a type of practical rationality, but the questions of what we will make our choices based are on largely left up to our autonomy to decide. Thus, in Existentialism is a Humanism, Sartre works from the case of the young man who must decide whether to serve France, his mother, or the church. For Sartre, we will never have enough evidence to decide the most important questions rationally (i.e., there's no sausage machine -- there's rats, pigs, whales, and chickens and you've got to decide what they are there for).

To sum up, both share a belief in autonomy and some idea of rationality, but for Sartre both are ultimately species of autonomy. For Kant, autonomy is about a will ordered under reason. In a sense, they are both inheritors of Descartes and the outcome of the Meditations where we have faculties of will and reason -- and one can outrun the other and go wrong. For Descartes and Kant, will is the source of error. For Sartre, false belief in "reason" is.


It might be similar in spirit, but not in effect. While they both appreciate the unity in equal application of morality among humans, (and, incidentally, both view morality as something uniquely human), Kant walks away with an imperative--a rule--whereas Sartre walks away with, at most, a guideline: that whatever you do, you're defining humanity, so take that into account when you act (in an absolutely free way).

The main advantage of Kant's way is that it cannot be ignored. There is an imperative; if you break it, you have done evil. You are still free to act as you will, but he will call you out whenever you are being inconsistent, and say you should be punished.

Sartre's, in that it leaves the judgment to you, has some other advantages. For example, it gets around the level of specificity problem: whereas Kant says you can never lie, and doesn't explain why there are not sub-categories of lies that might be acceptable (like lying during board games), Sartre allows you to do either, as long as you recognize that it's now something people do.

Another distinguishing factor is that Sartre does not require full universalizability. You might lie in Sartre's world, and you might tell the truth. These are both things people do. Now, the more truth you tell, the more trustworthy people are, and the more you lie, the less, so if you appreciate the system of trust, lying often would be inconsistent, and telling the truth wise. But you can do some of each without instantly breaking the rules. But of course, there's no clear line or rule here, and this might be used to justify any degree of lying as "not that bad."

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    First off, welcome to philosophy.se. Even though I'm listed as asking the question, it wasn't originally mine -- I had just bothered drafting an answer and then the op deleted the question. Regarding your answer, the overall gist of your answer is pretty good but there's a few stylistic and factual errors. On the style side similar in "spirit" but not "effect" is a weird construction. On the fact side, Kant actually does talk about harmless banter in MPV ("Doctrine of Virtue") in regards to being a pleasant person.
    – virmaior
    Commented Jun 1, 2014 at 14:11
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    Looking more carefully at the content, I would say change "it cannot be ignored" to "it applies regardless of your personal advantage". And beneath that "bad person" is not good Kantian language -- it becomes a bad action. (For more about good and bad persons read his Religion within the bounds of reason alone. Also, I'm not sure if "full universalizability" really amounts to a difference. It's rather than for Sartre you are creating your moral evaluations through your actions. It's a very dialectical (Hegelian) modification. (Good = what I approve of/do / bad = what I don't do)
    – virmaior
    Commented Jun 1, 2014 at 14:14
  • All of that being said, I gave you a +1.
    – virmaior
    Commented Jun 1, 2014 at 14:14
  • Good job calling me out on the "bad person" bit -- my bad. Can you tell me more about that "harmless banter?" As for the "full universalizability" angle... I could use killing as an example. For Kant, killing one person creates a logical inconsistency and breaks the categorical imperative. For Sartre, there's no such all-or-nothing effect: "good" is now a little bit more like "killer," as killing is something you do now, but if you don't do it much, it's not instantly inconsistent and immoral to kill while wanting to live.
    – Daniel
    Commented Jun 17, 2014 at 3:52
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    harmless banter is from Metaphysics of Morals under the section on lying and how it's a wrong against not others but your own rationality. In the casuisitical question, he says harmless banter is surely not wrong. Universalizability is straight out of the Groundwork and characterizes the first pair of forumlations of the CI.
    – virmaior
    Commented Jun 17, 2014 at 9:51

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