7. What is a good will? Kant thinks that to have a good will, you must do something because you know it is right.

Feelings and desires, for example sympathy and self-love, do not have moral worth according to Kant. (Kant calls feelings and desires “inclinations”.) You might act with sympathy on many occasions – he does not rule this out – but an act is morally admirable for Kant only because it is an act of duty, i.e. is done from duty.

Say that you decide to visit an ill friend in hospital. You might be motivated to do this out of self-interest; for example, to get in good with your friend because you are after a favour from them. Obviously, there is nothing morally admirable about this. However, you might instead be motivated out of sympathy or friendliness. Isn’t there something admirable about this? Kant claims that, although there is nothing wrong with feelings of sympathy and friendliness, it is not what makes your visit morally admirable. The only motive that makes your action morally admirable is that it is done from duty: you visit your friend because it is the right thing to do. For example, you know that they will be lonely and upset, they are your friend, and friends should take care of each other in situations like this. Importantly, you would be prepared to visit them no matter what you happen to feel about the prospect of a trip to the hospital.

If you are only motivated to do something because of your feelings, your grip on doing the right thing is very fragile. Consider our example of the hospital visit once more. Say, you visit your friend in hospital because you feel like it: you like your friend, you’re worried about her, and this makes you want to cheer her up. What happens when your feelings change? Say at the last minute you realise “I don’t like hospitals, they smell horrible, they are depressing, my friend will be in a bad mood, who needs that?” If feelings or inclinations are your guide to what you should do, then when they change you should change your plan accordingly. But this makes your judgement of what you should do depend on how you are feeling at the moment. For this reason, Kant thought that feelings are completely unreliable guides to what you should do. Even when they guide you in the right direction (as they initially did in our example of the hospital visit) they don’t do so reliably.

What we need is a reliable guide to doing the right thing. Feelings or inclinations don’t provide this. What does? Kant’s answer is reason provides you with that guide.

8. What makes something a duty? How does reason guide us in deciding what the right thing to do is? How does reason tell us what our duty is? Kant answers this by giving a theory of the categorical imperative. What is the categorical imperative?

The categorical imperative contrasts with what Kant calls hypothetical imperatives. An imperative is an order or demand. “Close the door” is an imperative. Hypothetical imperatives are imperatives that are given for particular reasons. “Close the door, if you want to stay warm” is a hypothetical imperative. The general form is: do X, if you wish to achieve Y. The categorical imperative, by contrast, merely makes demands upon us: do X.

For example, Kant held that it is a duty to tell the truth. Therefore, he thought that we should recognise the following imperative: always tell the truth. Why? Not because we want to get something from telling the truth. You tell the truth because it is right. Period. By contrast, the imperative: always tell the truth, if you wish to be trusted describes a hypothetical imperative. There is nothing wrong with hypothetical imperatives. It is just that, according to Kant, they don’t describe moral duties.