Dr W Large

The Postulates of Pure Practical Reason

Religion and ethics are inseparable bound together for Kant. It is not ontology, what things are, that proves the existence of God, but ethics, what ought to be. First and most important of all, one must realise that when Kant is speaking about ethics he is talking about ourselves. The universe is not ethical, nature is not ethical, and not even animals are ethical. The only beings which are ethical are in fact human beings. The question, then for Kant, is what does it mean for us to be ethical? The first answer to this question is that we are free. But what is freedom? It is not a natural property of things for Kant. We are not free in the same way that you or have brown or blond hair. Freedom is not an attribute, but an idea which motivates my actions. It is very important that we keep separate ethical and ontological language, and no more so than when we speak about God. I am free not because I am free, in the same way that I tall, short, beautiful or ugly, rather I am free, because I can think that I am. This is why Kant can say, in his lectures on education, that we do not consider children to be free, because they do not yet understand the meaning of freedom.[1] But what has freedom to do with morality? The reason why we do not think children are moral at an early age is that we do not expect them to be responsible for their actions, no more than we would expect a dog to be responsible or lion for eating an antelope. The reason that we tell a child for acting immorally is because we expect, as they mature, that that they will begin to understand what it means to act morally. When I say that you are responsible for your action, I mean that you ought to be able to give reasons for them. Thus, for Kant, morality and reason is one and the same thing. Humans are moral, as opposed to animals, plants and rocks, because they are capable of reasoning. If we did not have reason, then it would not possible to be moral: we would act from feelings just as animals and children do, and the only thing that would prevent us from doing anything wrong would be pain or pleasure. Yet it does appear than human beings do act from principles and ideas, and therefore are more than just complex animals.

What does a rational morality, however, look like? It means that I act from principles rather than from self interest. But what does it mean to act only on principles and what is good in itself? Kant distinguishes between two different kinds of goods, ones which are desired for the benefits they might give me, which themselves can be divided into two kinds: natural virtues such as courage, warm-heartedness and so on, and ‘gifts of fortune’ (wealth, good looks and health for example), and that good which is desired for the sake of goodness itself.  For Kant, morality is not for the sake of happiness, but for the moral law. I am moral because it is moral to be moral and not because I can any thing from being moral. I can will the moral law despite any benefits or results that it might bring to me. I will the good for itself as a universal principle, and it is this principle which governs the other goods of life, such as any virtues or external properties:

The Good will is not good because of what it effects or accomplishes or because of its competence to achieve some intended end; it is good only because its willing (i.e., it is good in itself).[2]

In the same work that this quotation comes from Kant gives an example to explain the difference between acting from self-interest and acting from principle:

It certainly accords with duty that a grocer should not overcharge his inexperienced customer; and where there is much competition a sensible shopkeeper refrains from so doing and keeps to a fixed and general price for everybody so that a child can buy from him just as well as anyone else.  Thus people are served honestly; but this is not nearly enough to justify us in believing that the shopkeeper has acted in this way from duty or from principles of fair dealing; his interest required him to do so.[3]

We can easily see, therefore, what it would means not to act out of self interest; it would be to carry out the same kind of action, but for its own sake, because it was good on principle and not because one gained any profit from it.  We can see the difference, but this quite different from saying that acting from principle is actually possible and exists.  To do this requires a much deeper philosophical investigation.

First of all let us ask ourselves what would be the difference between an act done from self interest and one done from principle.  The difference, Kant thinks is a difference between subjective and objective acts.  An act which is self interested is by definition subjective, and it is only because we are able to conceive of objective motivations for action that we can equally conceive of truly moral acts which would not be mixed with self interested motives. This naturally leads us onto the next question.  How can we make the distinction between the subjective and the objective?  This is of course is not a problem in the realm of theoretical knowledge, for I know that the truths of science of mathematics are not merely true for me, but also true for all other rational beings.  In fact the very notion of rationality is dependent on idea of truth being universal and objective. But why should we suddenly think objectivity is to be forfeited as soon as we enter the ethical sphere? We only do so because we think that ethics has something to do with feelings and sentiments and not with reason. But we are rational beings, Kant would argue, and thus our morality must also be able to be rational.  In fact Kant would turn the argument the other way around.  The problem is not one of trying to apply our morality to a rationality which appears to be alien to it, but that we are only moral beings precisely because we are rational. Thus, our morality does not come from outside ourselves, either as a natural law, or a divine commandment, but is the external manifestation of our own essence which is rational.  Only we have responsibilities because we have rationality.  A being that is incapable of grasping the universal, is equally incapable, for Kant, of being truly moral.  Thus morality and rationality are the same.  It is only because we are capable of abstraction that we can govern our actions by principles, and also expect other rational beings to do so.

This tells us philosophically how it is possible to be objectively moral, be rational, but it does not tell us in principle how to apply this rationality to our moral experience. Kant believes he has also crossed the divide between moral theory and moral practice, and that is by a procedure which he calls the categorical imperative. Morality can be rational only if it follows a law which is grounded in objectivity rather than subjective desires or inclinations. Just as there are laws of nature, Kant argues, there are laws of freedom. These laws are rational laws. That is to say that they are discovered by reason itself. The force of duty for the rational being is not external punishment but reason which discovers these laws through the operation of a procedure that Kant calls the categorical imperative. It is defined as follows: ‘I ought never to act except in a way that I can also will that my maxim should become a universal law.’[4]  This sounds very abstract, but if we look at one of Kant’s examples (and he gives many), I think that its obscurity will vanish.  Take the example of promising.  Let us say that I desire to, if I am in difficulties, to make a promise with the intention of not keeping to it, can I will this as a moral principle?  Again we have to distinguish between self-interested action and acting on principle.  Obviously prudentially I might say to myself that I should always keep to my promise because otherwise I might get a bad reputation.  But this, for Kant is not acting by a moral principle.  How then can I approach this question in a purely moral way? The answer for Kant is not through a supposedly moral sentiment, and still less by what people might think of me, but rationally.  Can I make not keeping promises a rational law?  But what do we mean by a rational law when we are speaking about morals.  It would be a law that would be universal, that is, one that would be binding both for me and others as rational beings.  And I can easily see if one of my desires is universal and rational in this manner by universalising it.  Thus can I will not keeping promises as a universal law?  Kant says it’s obvious that I cannot.  I cannot both rational will this as a law and also will my own subjective desire to not keep promise, since not keeping promises is parasitical on promising. One needs to stress here that what determines morality for Kant is rationality, for it is only rationality which allows me to step outside my own self interest, for it’s rationality which can create laws which by their very universality could cover both self and others and thus act as bridge between my own world and theirs.  Or perhaps it is better to say this:  it is because I am a rational being that I already belong to a world of being with others, and this being with other rather than something outside of me is the condition of my own most inner being.  Rationality by definition cannot be subjective, but must be intersubjective.

What has any of this to do with religion? Kant writes something very strange at the end of the Critique of Practical Reason: ‘It is morally necessary to assume the existence of God.’[5] We know from the previous lecture that Kant dismisses any theoretical proof for the existence of God. You can think the idea of God as much as you like, you might even think it necessary, but this is no implies that you have any knowledge of God, or that there is any object which corresponds to this idea. Indeed, a large part of the Critique of Pure Reason, the transcendental dialectic is only there to rid from philosophy once and for all these pseudo problems. Kant is the first philosopher to separate philosophy from its slavery to theology. The foundation of philosophy is science, not superstition and fanaticism. So why suddenly in these pages do we get God back again, and do we even get God back in the same way? We need to be very careful of claiming that philosophers are contradicting themselves, before we look carefully at their arguments. As Christopher McCammon writes, we must see religion as making up something that is lacking in morality, rather than as a substitute for rationally, it rationally tell us how we must exceed what reason can give us.[6]

What then is it within morality that requires that we exceed its limitation in order to go beyond it into religion? It is the idea of the highest good. Just as we require completeness in theoretical knowledge, but cannot prove, since the totality of conditions is not a possible object of experience, so our moral lives also require completeness. How then does Kant define the idea of the highest good? He writes that it is the unity of virtue and happiness. But why should such a unity require the existence of God? Because we know, when we look around the world, that those who are virtuous are not necessarily happy, and those who are happy are not necessarily virtuous. There does not seem to be any agreement between the causality of nature and the causality of freedom. It could be just by change that one’s virtue is rewarded by happiness, or equally that it is not. Here, Kant argues, our position is very different from ancient philosophy, which either in the form of Epicureanism or Stoicism, the one deducing virtue from happiness and the other happiness from virtue, believed that it was possible to reach the highest good within this world. But this is to overestimate the finite power of human beings to make nature agree with freedom. This is why morality requires the supplement of religion, so as to make good what it cannot achieve, but whose non-achievement would lead the destruction of our moral progress, it would be directed, Kant writes to ‘empty imaginary aims’.[7] If existence in this world were the only possibility of our being, then the highest good would be impossible. But there is an intelligible world, just as much as a natural world. My reason, therefore, postulates the immortality of my soul such that I could achieve the unity of virtue and happiness. But we do need to be very careful here. It does not prove the immortality of the soul, in the way that theoretical reason would in the conjunction of intuitions and concepts. There is not intuition of the immortality of the soul (this would lead, in the vocabulary of the Critique of Pure Reason to a paralogism of reason). Rather it can only be an idea of moral reason, which give to reality its ultimate purpose, but which I cannot achieve in this life.[8] I can think this idea as possible through reason, though there is nothing in the real world that might confirm it. That I have this idea, however, has real effects, since it determines, through the idea of freedom, what I actually do in this world. It effects my behaviour and how I relate to others. We must distinguish between that which is in my power, and that which is beyond my power: the full realisation of the highest good which I can have must be an ideal only.

We can see the same reasoning acting for the postulate of the existence of God. Happiness is the condition of a rational being where there is perfect harmony between world and our will; that is, the harmony of nature and freedom, but we, as rational beings, are not the cause of nature and so we cannot expect it to be one with our will. Thus there is no link in the moral law between morality and happiness. In terms of reason, which aims at the highest good, i.e. completion, we have to postulate that such a unity is possible, even we cannot achieve it. The only being who could do so would be God, who is both the cause of nature, and whose will is perfectly determined by the moral law. There is an ethical harmony between virtue and justice, which replaces Descartes’ ontological harmony. I do not know if the world will be just, but I have to act morally as though it were possible as the ultimate goal of my actions.

Such a postulate, however, and Kant underlies this over and over again in the Critique of Pure Reason, is only a ‘subjective necessity’ and not an objective one.[9] The necessity of accepting the immortality of the soul and the existence of God in moral reason does not make good what cannot be proved in theoretical reason. In other words, I cannot prove God exists as an object. This require a sensible intuition which is completely lack. I cannot experience God as I experience an object within the world. Rather Kant is argue that to make my moral world complete, I need to add the supplementary idea of God existence, whether God actually exists or not, I still cannot know, even morally. We cannot, for example, think of the origin of freedom, theoretically; that is to say, give a scientific explanation of its meaning, as we would for gravitational force. Rather we can only say that to make sense of morality we have to postulate freedom, since without it they can be no ethics, but we cannot prove the existence of freedom with a test tube. God is not a concept which belongs to physics but to ethics.








[1] And non-Europeans, Kant adds in his usual racist and Eurocentric manner. See, Kant, Education, University of Michigan Press, 1960, 4.


[2] Foundations of the Metaphysics of Morals in Kant Selections ed. L.W. Beck, p. 249.


[3] H.J. Paton, The Moral Law, (London: Hutchinson & Co. Ltd., 1948), p. 63.

[4]ibid. p. 67

[5] Kant, Critique of Practical Reason, translated by L. W. Beck (Indianapolis: The Bobbs-Merrill Company Inc., 1956) 130.

[6] See, ‘Overcoming Deism: Hope Incarnate in Kant’s Rational Religion’, in Kant and the New Philosophy of Religion, C.L Firestone & S Palmquist (eds), (Indiana University Press, 2006) 87-8.

[7] Critique of Practical Reason, op. cit., 118.

[8] I might find that when I die, there is no immortality of the soul, but this still would not prevent this idea from directing my morality in this world.

[9] The Critique of Practical Reason, op. cit., 130.