1. MEANING OF THE WORDS: Literally translates as supreme good’. Kant uses it to mean the ‘highest happiness’.
  2. WHAT IT ISReceived in the afterlife, the summum bonum is a reward for acting out of one’s duty, as long as one acted autonomously. The summum bonum is a happy, fulfilled state of mind.
  3. WHY IT’S PART OF KANT’S THEORY: The summum bonum is a necessary reward as otherwise it would not be rational to act morally. E.g. Hitler did terrible things but killed himself before receiving punishment, while morally good acts often go unrewarded and unnoticed (e.g. heroes dying in war).
  4. The existence of the reward therefore makes being morally good a rational decision – it ensures justice is served for those who acted morally/dutifully.
  5. HOW TO GET THE SUMMUM BONUM: The categorical imperative has to have been followed in order to have known what your duty was/is and then acted on. The reward is not available for those who performed ‘good’ actions for any other reason (For example, because of the consequences or because they acted purely out of emotion).
  6. WHY YOU MUST ACCEPT THE 3 POSTULATES: If you accept the truth of the summum bonum you must also accept the truth of the following:
  • THERE IS A GOD: Only a divine being could have the knowledge required to reward the dutiful (God is omniscient). Furthermore, this reward of pure joy could only be given by a wholly good being (God is omnibenevolent). Lastly, this kind of reward could only be given by a being with power to do so (God is omnipotent). Kant argues the innate moral law also acts as proof of God’s existence – claiming it is the best and only rational reason to accept the truth of God’s existence.
  • WE HAVE IMMORTALITY: There must be an immortal soul because the reward of ‘highest happiness’ could not possibly be obtained in a mortal life as such a joy could not be experienced in this, physical, world. Furthermore, a reward would only really make sense when we have finished making moral decisions (i.e when we die. The summum bonum is therefore awarded to the immortal soul in the afterlife and, for that reason, many have compared summum bonum to heaven.
  • THERE IS THE POSSIBILITY OF FREEDOM: To obtain the summum bonum you must have acted freely, or a reward would not be appropriate. Therefore, freedom must be possible. Because someone who acts morally, but not freely, cannot obtain the summum bonum. This is one reason you should not lie or undermine the autonomy of others. It is another good reason not to use others as a means to an end.                                                 Together these are known as the Postulates of Practicle Reason. What Kant means is that they explain why being moral is also being rational. Morality is reason made practical (put into practise).

7. THE QUESTION OF WHETHER THE SUMMUM BONUM IS ACTUALLY A GOAL: Some people               argue that the summum bonum is actually a goal that makes Kant’s approach to ethics teleological rather than             deontological. However, we can respond that if you acted morally only to obtain the summum bonum you                     wouldn’t have acted dutifully and so you wouldn’t actually get the reward at all. Therefore it would be irrational to       work towards a goal if working towards that goal actually deprived you of the goal. Thus meaning it would be               irrational to treat the summum bonum as a goal.