In Wealth of Nations, Adam Smith argues that the aggregation of the preferences of consumers and producers for a given good is in the public interest for the product or service. Often overlooked is Smith’s Theory of Moral Sentiments, in which the famous economist wraps a moral sentiment around the individual preferences, hence hopefully constraining them, albeit voluntarily. Herein lies the rub, for it is shaky to assume that a preference that seeks to maximize itself will voluntarily restrain itself when it rubs up against an ethical limit that is felt. Such a moral constraint is like a semi-permeable membrane in that the sentiment naturally triggered when a person comes on an unethical situation or person can be ignored or acted on.
The full essay is at “Private Interests Over the Public Good.”