The foundation of morality has long been a central concern in philosophy. Two influential figures who offered distinct perspectives on its origin and justification are David Hume and John Stuart Mill. Hume, an empiricist, posited that morality stems not from reason but from sentiment, specifically our feelings of approval and disapproval towards certain actions and character traits. In contrast, John Stuart Mill, a proponent of utilitarianism, argued that the moral worth of an action is determined by its consequences, specifically its ability to produce happiness for the greatest number of people. Examining their approaches reveals a fundamental divergence: one locating morality in subjective feeling, the other in objective outcomes.
David Hume’s treatise A Treatise of Human Nature (1739-1740) presents a radical challenge to rationalist ethics. He famously declared that "reason is, and ought only to be the slave of the passions." For Hume, moral judgments—whether we deem an action right or wrong, virtuous or vicious—are not derived from logical deduction or factual observation alone. Instead, they arise from a direct emotional response, a sentiment of approval or disapproval, triggered by witnessing an action or contemplating a character. This sentiment, he argued, is universally shared, albeit with variations in intensity, due to the common nature of human psychology. For instance, acts of generosity and kindness evoke a feeling of pleasure and admiration in the observer, leading to their classification as virtuous. Conversely, cruelty and treachery elicit feelings of displeasure and aversion, marking them as vicious. Hume's emphasis is on the feeling elicited by an action, not on an abstract rational principle or divine command. This view grounds morality in human nature itself, making it an observable phenomenon rather than a metaphysical construct.
John Stuart Mill, building upon the work of Jeremy Bentham, offered a consequentialist framework in his essay Utilitarianism (1863). For Mill, the principle of utility, or the greatest happiness principle, serves as the ultimate standard for morality. An action is right in proportion as it tends to promote happiness, wrong as it tends to produce the reverse of happiness. Happiness, in Mill’s refined version of utilitarianism, is understood as pleasure and the absence of pain. Crucially, Mill distinguished between different qualities of pleasure, arguing that intellectual and moral pleasures are superior to purely physical ones. This nuanced view allows for a hierarchy of pleasures, suggesting that a satisfied pig might be less content than a dissatisfied Socrates. The moral decision-maker, therefore, must consider the consequences of their actions, aiming to maximize overall well-being. This requires a calculation, albeit a complex one, of the potential happiness or unhappiness generated by a course of action for all affected parties. Unlike Hume’s focus on immediate sentiment, Mill prioritizes the long-term outcomes and the collective good.
The implications of these differing foundations are significant. Hume’s sentimentalism suggests that moral disagreements might, in part, stem from differences in emotional sensitivity or the specific sentiments evoked by particular circumstances. It offers an explanation for why certain universally condemned acts, like torture, seem to provoke a visceral, immediate moral revulsion across cultures, independent of complex reasoning. However, it also raises questions about the objectivity of morality. If morality is simply a matter of feeling, can we definitively say that one person’s moral sentiment is more valid than another’s? Mill's utilitarianism, on the other hand, provides a seemingly more objective framework for ethical decision-making. By focusing on measurable consequences (happiness and pain), it offers a method for resolving moral dilemmas through calculation. Yet, utilitarianism faces its own challenges, particularly in predicting all consequences, in ensuring fairness when individual happiness is sacrificed for the greater good, and in defining what constitutes "happiness" in a universally agreeable way. For example, can the happiness of the majority justify the severe suffering of a minority? Mill’s emphasis on quality of pleasure attempts to mitigate this, but the tension remains.
In essence, Hume locates the spark of morality within the human heart, an inherent capacity for fellow-feeling that guides our judgments. Mill, conversely, places the moral compass in the external world, directing us to assess actions by their capacity to improve the human condition. While Hume’s approach speaks to the immediate, felt experience of morality and the intrinsic social nature of ethics, Mill’s offers a systematic, forward-looking principle for social reform and individual conduct aimed at collective flourishing. Both, however, contribute profoundly to our understanding of what it means to be a moral agent and how we arrive at our ethical conclusions.