In The moral problem (1994), Michael Smith tries to link three
conflicting theories that alone are intuitively plausible, nevertheless, they do
not seem to work well together. The first proposes that moral judgments are in
fact beliefs about objective matters. The second states the concept of “practicality requirement”. The third is a humean belief-desire psychology,
i.e. if a moral judgment is sufficient to explain actions, then it must
involve a desire. If that is the case, it cannot be simply a belief. For Smith, any
attempt to solve the moral problem must find a way to hold all three doctrines.
I will argue that his solution rests on two false assumptions. The first, a
rationalist one which supports that what we have reason to do is what we
would desire to do if we were fully rational. The second is the internalist
thesis about moral motivation according to which a person who believes she is
morally required to do something is either necessarily motivated to do it or
she is practically irrational. I will base my critics on four objections raised by
Copp, Miller, Shafer-Landau, Brink and Sayre-McCord.