A new worry for the Humean internalist

The Humean internalist finds Humean motivational theses and reasons internalism to be independently attractive. She therefore combines them, in the hope of creating a theory of reasons that is attractive for all of the reasons that each thesis is attractive. On this score, she succeeds. However, there is a drawback. Those who build a theory of reasons by combining Humean motivational theses and reasons internalism face a dilemma. If you combine these views, either you are committed to a theory of reasons that allows all of a person's reasons to simultaneously change, erratically and randomly, or you are committed to a theory of reasons that fixes a person's reasons at birth, in which case they remain stable and unchanging over a lifetime. Neither alternative is attractive. Humean internalism cannot navigate a path between these two extremes, and this should worry the Humean internalist.