Ashley asked:

Why is it difficult to show that a person has acted from duty?

Answer by Peter Jones

It would be impossible, not just difficult, to show that a person has acted from any particular motive, or indeed from any motive at all. All we see is what they do. The rest we have to guess, or we might simply believe what they tell us. Either way we cannot show that a person is acting consciously, so other people’s motives must be imputed and never known for certain.

Sometimes when we act it is difficult even for us to tell why we did so. Did we give that Christmas present out of duty, or was it pure generosity?

In short, the reason why it would be impossible to show that a person has acted from any motive is the ‘other minds’ problem. There would be no way to show that they have one.


Answer by Geoffrey Klempner

In the Groundwork for the Metaphysic of Morals Kant argued that the only morally worthy action is one done from duty. But he added the caveat that it can be difficult or impossible to determine with certainty whether a person’s action is genuinely motivated by the thought of duty (the thought of the Categorical Imperative) or some mere ‘inclination’, i.e. non-ethical desire.

If I say to you, ‘I did what I promised because I believe that one ought to keep one’s promises,’ you might still be left wondering whether this really was my motivation, or whether, on the contrary, what motivated me was the thought of the unpleasant consequences that would follow if you, or others, concluded that I am the kind of person who does not keep his promises.

The problem is that there are all sorts of very good prudential reasons for acting ethically, so in a sense an ethical act is often over-determined. It was my duty to do X (e.g. keep my promise) but it was also in my own best interests to do so.

In formulating his theory of the Categorical Imperative, Kant was keenly aware that there are theories according to which the only reason for acting morally is prudential. We do what is right because it is ultimately in our best interests, or the best way to be happy, etc. The problem is, as Kant argued, any such ‘contingent’ motivation cannot be relied on.

The movie The Godfather is a good example: ‘I’ll make him an offer he can’t refuse.’ The fear of death by torture would, for many persons, trump any moral considerations.

Hence, the search for an ‘a priori’ prinicple that doesn’t depend in any way on the beneficial consequences for the agent. The truth of such a principle doesn’t require that we be able to determine whether it is motivationally effective in any given case.

However, if someone does the ethically right thing despite the threat of death by torture, that’s pretty good evidence that what motivated them was the thought of Kantian duty.