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Sunday, 14 March 2010

An explanation of Kant's moral argument

Kant’s moral argument focuses on the notion that God must exist to provide structure to the moral universe. Technically he did not believe that is was possible to prove the existence of God through rational or empirical means. It is important to outline two key ideas before explaining the details of the moral argument. These ideas centre around his assumptions of the universe: that the universe was fair; and that the world around us is fundamentally rational. He begins with the unspoken assumption that the world is fair, owing to the dominance of the enlightenment belief that the universe was fundamentally knowable through reason. It is important to note that Kant began a new way of looking at knowledge. He believed that we could know the world through reason in a prior synthetic way. This was a complete change from how the world had been view previously and was known as Kant’s Copernican revolution. In essence Kant believed in two separate worlds of knowledge: noumenal and the phenomenal worlds. The noumenal world is the world as it truly is without being observed. It is fundamentally unknowable because the act of observation changes the very thing that we observe. It is as though human beings have a specific set of spectacles that cannot be taken off and like the proverbial rose tinted ones they change our perception of the world around us. This personalised view of the universe is the phenomenal world. However, what is key to explaining Kant’s moral argument is the fact that reason is the tool that can be used to know the true nature of the universe as it does not and cannot change.

Kant’s moral argument focuses on reason, good will, duty and the notion that we ought to strive towards moral perfection. It begins with the claim of two things that have him in awe: the starry heavens above; and the moral law within. This moral law for Kant was universal and objective. An example of this might be seen in the wide scale agreement that murder or torture is wrong. There seems to be agreement across cultures that certain actions are intrinsically wrong. This, for Kant, suggests that there is a universal objective moral law. He believed that the highest form of goodness was the notion of good will, namely that someone would freely choose to do good for no reward whatsoever, only for the sake of goodness. Moreover, Kant believed that we have a moral duty to do such good things. He would argue that we have an awareness of what is right and wrong and that good will should make us act accordingly as reason dictates this to be the case. In a way it doesn’t make any rational sense to act in an immoral way. If I were to act out of nepotism (favouritism) or from emotion then I could never discern the universal objective moral law as these factors would cause me to change my opinion of what was right or wrong depending on how I was feeling or what the circumstances happened to be. So I must choose the good based on good will and reason. Duty was seen by Kant as a way of fulfilling this end without being misguided by emotion or factors of personal gain. It is here that we come to a key point in Kant’s argument, namely the notion of ‘ought’ implies ‘can’. He believed that we can only have a duty to do some thing that we can do. For example, I cannot have a duty to fly unaided as it is not something that I can do; or if I were to come across someone drowning in a lake but could not swim Kant would suggest that I would not have a duty to jump in and save them. My duty in the latter case would be to find someone who could swim so I would need to raise the alarm. Once we have this notion of ‘ought’ implies ‘can’ in our mind the argument becomes much clearer. If I can choose to do the good (using reason, good will and duty) in one case then I should be able to do this in every case, moreover that I have a duty to achieve this moral perfection. Kant called this moral perfection the Summum Bonum. He argued that the Summum Bonum was a state of moral perfection existing coincidently with perfect happiness. It is important to note, as stated earlier, that Kant did not believe that acting out of self interest (in this case achieving perfect happiness) would ever bring us to the correct moral decision. If my aim in life were to achieve perfect happiness then this would not cause me to act morally. For Kant, the problem for human beings acting morally was that it did not lead to happiness. I could be the most moral person in the world yet personal tragedy could befall me, while another individual may lead an immoral life and be happy in some way. This would appear to make the world unfair and would potentially discourage us from acting morally at all. Kant believed that we must have a duty to achieve the Summum Bonum and because it was not achievable in this lifetime that we must be able to achieve this in the next life.

It is here that we come to the conclusion of Kant’s moral argument. Notice that Kant does not see this as ‘proof’ of God’s existence only that in order for moral behaviour of human beings to make sense we must postulate three things. These are known as the three postulates of practical reason: free will, immortality of the soul and God. Kant believed that if we were not free to make moral decisions then we could not achieve a state of moral perfection because we would not be morally blameworthy or praiseworthy for our actions. He also argued for the immortality of the soul as we have seen above; behaving morally in this life defies reason if we cannot achieve the Summum Bonum in this life, as others who act immorally appear happy as opposed to those who behave morally, not to mention the fact that we may die before this state of moral perfection is reached. The afterlife is therefore necessary to provide the opportunity to achieve the obligation of moral perfection and perfection happiness that reason dictates. The final part of the conclusion of Kant’s moral argument is that God must exist as a postulate of practical reason. Without the existence of God we cannot have the afterlife and we would not be able to fulfil our obligation of reaching the Summum Bonum. Therefore God is necessary to ensure fairness in the universe and provide the exact coincidence of moral perfection and perfect happiness known as the Summum Bonum.


  1. I'm a Philosophy student in Oxfordshire, three weeks away from my AS level in it. I just wanted to thank you for the help of your blog. It has been beyond useful in my revision and securing of understanding of the key topics.

    Eternally grateful, and thank you for your hard work, sir!

  2. Thanks allot for these posts!