Immanuel Kant was a German philosopher who is now famous for his concept of the ‘categorical imperative’. Similar to the ‘golden rule’ found in many religions (do unto others as you would have them do unto you), the categorical imperative works as a kind of handbook for determining whether an action is moral or immoral. The idea is that you should consider an action moral only if you could sensibly wish that all people in that situation would act in the same way. In other words, before you make a moral decision, you should ask yourself whether it would make sense for everyone to make the same decision.

This is known as the ‘test of universalisation’. If you can wish that a ‘maxim’ (a rule of conduct) be universalised, then that maxim is moral. If the universalisation of the maxim results in a logical inconsistency, however, that maxim should not…