Hume explained the “Problem of Moral Motivation” which is that humans are not motivated by reason; sentiment motivates humans.
If a woman’s house is partially consumed by a fire, and her child is still inside, reason would tell her not to run inside a burning building. That would be reasonable because all living beings’, for human and non-human animals’, first instinct is to survive. Staying outside where the fire cannot harm her is rational. Fortunately, humans are not solely controlled by reason, but also sentiment. The woman runs back into the house for her child based on sentiment; these feelings she has for her child motivated her to enter the partially burning house and save her child.
In the same way that humans are not solely controlled by reason, humans are not controlled exclusively on feelings because an individual’s sentiment is aided by reason.