David Hume’s version of emotion-based morality rests on the idea that morality is derived from sentiments and not from reason. He describes reason as a “slave” to emotions. Reason, Hume would argue, allows us to understand situational events, and facts. Sentiments are the feelings, or emotions, that one has in response to a reasonable understanding of situational facts.
One example is the decision to consume wine with friends. Hume argues that the impetus to consume the wine does not come from reason, because all reason can provide are the facts about the wine: people are drinking it, it is red/white, poured in glasses…However, the decision to drink the wine does not come from understanding situational facts, but rather by the emotive response one feels about the availability of the wine.
Another example includes the merchant who uses arithmetic to understand the numbers, however, it is not the actual numbers that determine the actions of the accountant, but the relationship of the numbers and the merchant’s reaction to the numbers as far as collecting debts.
I agree with Hume’s argument in one way; how can reason alone be the cause for moral action when moral acts are value-ridden? However, I disagree with Hume overall because there are problems with subjugating reason to passion: each moral agent is able to have an individual morality. The slippery-slope is one of moral relativism; if morality is based on individual impressions, emotions, and passions, then there is no account for people with different conditioning experiences that might lead to different moral choices and different moral feelings. For example, a starving child who steals bread to sustain his family is not a bad moral agent for Hume. However, a child who simply felt like a snack and steals bread might be a bad moral agent. There is no absolute moral rule for whether stealing is good, or bad.