The mixed maxims objection to Kant
Kant appears to think of all of our acts as based on maxims. A maxim, we can say here, is a general policy, such as increase wealth by every safe means or let no insult pass unavenged. According to Derek Parfit (2011: 285), Kant recommends the following test for when an act is morally wrong:
An act is morally wrong if it is done on the basis of a maxim that one cannot will to be a universal law.
In On What Matters, Parfit rejects this test, and some others that resemble it, by appealing to mixed maxims. My aim here is to present Parfit’s point, but I articulate it slightly differently from how Parfit does. My reason for departing from Parfit’s articulation is at the end of the presentation. Note: the definition above of a maxim is a simplification of Parfit’s definition (2011: 275).
The test attributed to Kant involves the following commitments:
(a) If we cannot will a certain maxim to be a universal law, then it is possible for an act done on the basis of that maxim to be morally wrong.
(b) If it is possible for an act based on a certain maxim to be morally wrong, then any act done on the basis of that maxim is morally wrong.
The mixed maxims objection targets (b). Parfit denies (b) because he thinks that there are maxims which it can be morally wrong to act on in some contexts, but in other contexts nothing wrong is done by acting on them. The maxim to never lie is one of his examples. In some contexts, it can be morally wrong to act on this maxim, for instance if one can save a life that will be unjustly lost by telling a lie. But in many other contexts, nothing wrong is done by acting on this maxim.
A mixed maxim is a maxim with the following properties:
(i) it can be morally wrong to act on this maxim;
(ii) it is not necessarily the case that an act done on the basis of this maxim is morally wrong.
However, this is not exactly how Parfit defines a mixed maxim. Parfit says that being morally mixed means ‘if we always acted on these maxims, some of our acts would be wrong, but other acts would be permissible or even morally required.’ (2011: 293) I have doubts about whether this definition captures exactly what he has in mind. To see why, consider again the maxim to never lie. Parfit counts this as a mixed maxim, but it is possible that a person who acts on it from their early years never does wrong, because they never find themselves in a situation in which it is morally required that they lie. In which case, why say that if we always act on it, some of our acts would be wrong? I am not sure if it is even very likely that such a person will do moral wrong because of their maxim.
Parfit, D. 2011. On What Matters, Volume 1. Oxford: Oxford University.