David Hume: Critique of Substance and Moral Emotivism

Hume's Critique of the Idea of Substance

The Illusion of Extended Substance

Hume criticizes the idea of extended substance. The idea we have of substance is that it is an objective reality which acts as the support for qualities and impressions. However, because our idea of substance does not derive from any specific impression, this idea cannot be held as valid. All our impressions last only a moment and then disappear; substance, instead, is conceived as having a continuous and stable continuity through time. Since no impression can be attributed to substance, we are left with the conclusion that it is a creation of our imagination. Despite this, the idea of substance remains a useful invention or belief for our survival.

The Rejection of Infinite Substance

Hume also criticizes the idea of infinite substance. This refers to the idea of God as a substance of infinite perfections. We must ask from which impression this idea of infinite perfection could possibly derive. Since the idea of substance is perfect and there is no corresponding impression, we must conclude that there is no teleological or metaphysical knowledge of God.

The Thinking Substance and the Self

Hume attacks the idea of the thinking substance. Traditionally, philosophy has understood the "self" as the subject that has perceptions, distinct from the perceptions themselves. Although the soul is thought to be the subject of impressions, there is no actual impression of the soul itself. On the other hand, impressions and ideas are constantly changing: one moment we feel cold, then we feel heat. Under these changing perceptions, a stable self and identity are supposed to exist as the core of our personality, but the ego is just like any other idea of substance—a fiction.

Moral Emotivism and Human Behavior

Hume was among the first thinkers to assert the fundamental role of emotions and feelings in human behavior. Hume maintains that, in fact, every action is based on emotion and sentiment. Our actions are motivated by feelings of attraction or aversion toward certain behaviors. This attraction arises from the pleasure or pain that certain actions provoke in us. Therefore, feelings of pleasure and pain are the basis of moral trials.

For Hume, sympathy is a characteristic of human nature. This is the natural inclination that humans feel, which arouses feelings of compassion and solidarity toward the misfortunes of others.