Speaking about Kantian ethics, I wondered how one could create a moral theory without knowledge of the world, based on the sole rationality. Without references to experience, what prevents us to develop a moral theory with arbitrary definitions of right and wrong?

Assuming this theory will be coherent, obviously.

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    Some might argue that the state of the universe is arbitrary, and that a theory based on that will be so too. So is there a chance to remove all arbitrariness from any given theory? Or, asked differently: How do you define "arbitrary" in such a way that not all moral theories are arbitrary but Kant's is?
    – Einer
    Sep 12, 2014 at 12:17
  • Let's define a theory arbitrary as a theory such that given its premises and assumptions and given a set of rules of deduction (commonly the usual logic), can arise multiple and contradictory conclusions. Thus for example, talking about the creation of a moral theory, one could say it's arbitrary if such a method permits the creation of multiple moral theories, with different and contrastating definitions of right and wrong. (i.e. theory A: murder is wrong, theory B: murder is not wrong, and both A and B obey Kantian assumptions on what a moral theory is)
    – seldon
    Sep 12, 2014 at 13:43
  • Anyway I'm not interested in other ethics but just in the way Kantian generates its own. Does Kantian ethics follow naturally from its premises or there are other, contrasting ethics?
    – seldon
    Sep 12, 2014 at 14:17
  • So you say a theory is not arbitrary if it's consistent. But then you state in your question that the theory is ought to be coherent and many people would say that coherency already implies consistency. So you say an a priori theory (like Kant's) could be coherent but not consistent? Maybe I'm just at a loss here...
    – Einer
    Sep 12, 2014 at 17:07
  • You are right, I was not clear. We have to distinguish between the moral theory itself and the framework from what is generated. What I'm saying is the framework could generate many coherent theories, but those theories could be not consistent if compared to each other. This make any claim that one of that theories naturally follow from the framework wrong. In particular the premises Kant make for his ethics the "framework" and his ethics a theory following from his framework. But is his ethics really the only, natural theory following from it?
    – seldon
    Sep 12, 2014 at 17:52

2 Answers 2


Kantian ethics, in short is Christian ethics; his innovation was to place it in an axiomatic basis that is his categorical imperative; in the same way that Descarte placed epistemology on an axiomatic basis (the cogito); and similarly Spinoza with Abrahamic theology.

All these attempts, at root, were inspired by Euclids successful attempt to place Mathematics axiomatically - his Elements.

  • In what sense is Kant's ethics Christian? He certainly does not think ethics is founded on revealed religion. Do you just mean that he was a member of a society whose values derived from the Christian religion? That seems true, and I'm sympathetic to understanding philosophers in their historical context, but what significance would it have for our philosophical evaluation of his theory? Has he failed to create an adequately purely rational basis for ethics and simply secretly smuggled in Christian beliefs? Maybe. But it's going to take some work to show that.
    – user5172
    Sep 12, 2014 at 17:40
  • @shane:Yes; I mean that his values were derived from Christian religion. Sure, one can question the adequacy of a rational basis for ethics; but that isn't the question I'm answering here. Sep 12, 2014 at 17:54
  • So your view is that yes Kant's ethics is arbitrary, despite his professed attempt to make ethics purely rational, because his ethics really comes from his Christian background? Like I say I'm sympathetic to that claim, but it seems to me that it's pretty controversial and that you need to give us a little evidence for it.
    – user5172
    Sep 12, 2014 at 17:57
  • @shane: How is that arbitrary? Your contention appears to be if its not purely rational then it must be arbitrary; perhaps you mean that it isn't universal? Bryan Magee, the British Philosopher, pointed out in his autobiography that Kants ethics, in his expression (but not how it was founded) is broadly akin to his Pietist background - and stated that this was hardly ever remarked upon. Sep 12, 2014 at 18:21
  • To say that Kant's ethics is just a reflection of his background is to say that if he had a different background he would have had a different ethics. If he had been raised in a different country, different time, he would have thought "universal reason" required something else. The whole idea of the enlightenment is to get rid of particularity, like being a member of a certain culture, certain religion, etc, precisely because these features are contingent. I thought your position was that Kant was trying to be universal but failing, and smuggling in his own, arbitrary, irrational views.
    – user5172
    Sep 12, 2014 at 18:24

I don't think Kantian ethics is arbitrary.

At it's core, Kant is this:

The idea of duty - if you follow your duty, you are doing a morally acceptable action.

While this may seem simple, figuring out one's duty is a more difficult task.

Kant's framework was quite simple, for verifying if something could be your duty.

  1. It must not treat anyone as a means to an ends
  2. It must respect the free will of parties concerned
  3. If the action were universalised, would it cause any fallacies?

This is where Kant stops becoming arbitrary - he has just given three tests to see if an action could be morally good. And these tests do require knowledge based on the world.

If you need a more specific answer, don't hesitate to comment or something. I am happy to have a productive debate on this stuff

  • Thank you for answering! However, I was talking about the way Kant deduces his ethics. Can it create only Kantian ethics or there other ethics compatible with it and not equivalent to Kantian ethics? (PS I'm not the down-voter)
    – seldon
    Sep 12, 2014 at 14:12

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