How did David Hume explain moral judgments?

David Hume argued that moral judgments are not based on reason, but are instead determined by sentiment or feeling. He maintained that because morality is essentially practical—meaning it must motivate action—reason alone is insufficient, as he famously regarded reason as the slave of the passions. While reason can help individuals achieve their goals, it cannot determine those goals or move one to act without a prior desire or feeling.12

In his work A Treatise of Human Nature, Hume defined virtue as any mental quality or action that evokes a pleasing sentiment of approbation in a spectator, while vice is defined by the contrary feeling. This perspective is central to his rejection of the idea that moral judgments reflect objective states of the world. Furthermore, Hume is noted for identifying the "is-ought" problem, often called Hume's Law, which highlights the logical difficulty of deriving moral values ("ought") from factual observations ("is").12