“If we look back upon all previous efforts that have ever been made to discover the principle of morality, we need not wonder why all of them had to fail. It was seen that the human being is bound to laws by his duty; but it never occurred to them that he is subject only to laws given by himself but still universal and that he is obligated only to act in conformity with his own will ..”
—Kant being very humble
Kant’s formula of universal law has some superficial appeal. On this principle, one ought only act in accordance with maxims that could be willed to be universal law.
What the hell is a maxim? It’s not exactly clear. It’s sord’ve like a rule or a principle. So when I try to maximize well-being, that’s plausibly a maxim.
These objections are not original to me—Parfit is responsible for all of these in his excellent series “On What Matters,” which you should all go read immediately. Act on that maxim! I will it to be a universal law!
What do we mean by making it a universal law? Well, roughly that it could be done universally.
One way of interpreting a maxim is that it is the principle that you in fact act on. So if I take your pencil because I think it will maximize well-being, maximizing well-being is my maxim.
If we interpret it that way then it runs into problems. Egoism plausibly can’t be willed to be a universal law. Yet not every act done by egoists is wrong. If an egoist saves the life of a child merely to gain fame, that act is not wrong.
Similarly, there are many good acts that would be impossible for everyone to act on. If I act on the maxim “don’t have children to have more time to spend on protecting the future of humanity,” that maxim couldn’t be universalized. Yet that doesn’t make it clearly wrong. Similarly, acting on the maxim “go to that secluded forest,” doesn’t seem wrong but couldn’t be done by everyone.
The other way of interpreting a maxim is that it’s a principle that could be acted on to justify an action. Yet this runs into problems. Any act has infinite maxims that could justify it. Suppose I steal a pencil. I could act on the contradictory maxim always steal, or I could act on the non contradictory maxim I always get to steal from the particular person from whom I stole, or even the maxim maximize well-being unless it conflicts with me stealing this person’s pencil and then do that.
For a maxim to justify an act it just has to include that act. However, the maxim can be tailored to include no other acts.
This view also runs into the problems given earlier. If I act on the maxim go to a secluded forest to meditate, that is not universalizeable but it’s still not morally wrong. If I were to go on a date with Jane, that wouldn’t be objectionable based on the impossibility of everyone simultaneously going on a date with Jane.
It’s also not clear what the justification is for this principle. Why would we accept that taking an action is wrong if everyone couldn’t do it? It’s not at all clear.
Parfit makes more objections, but these seem enough to refute it decisively.