This blog post examines how the sentimentalist perspective interprets and reconstructs David Hume’s theory of moral judgment, analyzing how the boundary between sentiment expression and factual description emerges as a central issue in moral philosophy.
Hume’s claim that deontic propositions cannot be derived from existential propositions has profoundly influenced modern moral philosophy. To moral philosophers who deny that moral judgments are propositions of truth or falsehood about facts and assert that moral knowledge cannot exist, Hume’s claim is regarded as a kind of scripture. However, debate continues to this day about what exactly Hume’s claim means.
MacIntyre argues that Hume’s claim does not target all existential propositions, but only a specific category of them. According to his interpretation, Hume only acknowledges the impossibility of moral judgments when they are derived from theological propositions concerning eternal finality or divine will. Since theological propositions are unrelated to human needs or interests, an unbridgeable gap inevitably exists between them and moral propositions. Ultimately, MacIntyre explains that Hume likely held moral propositions could only be derived from propositions of existence directly related to human needs or interests. This interpretation stems from Hume’s conviction that morality is a natural phenomenon related to human passions or emotions, arising from needs or interests. As evidence, MacIntyre points to Hume’s extensive citation of anthropological and sociological facts when discussing emotions, particularly in relation to how social rules promote the public good.
In this context, MacIntyre proposes the so-called connecting concept. This concept encompasses desires, needs, pleasures, and the like, relating to various aspects of human nature that are factual while also closely connected to moral concepts. According to MacIntyre, the connecting concept mediates facts by linking them to associated moral demands, and he argues this is precisely what Hume actually did.
Hunter also rejects the interpretation that Hume believed moral propositions could not be entirely derived from propositions of existence. Hunter argues that Hume understood moral judgments as factual assertions, like propositions of existence, and thus believed that moral judgments, as factual assertions, could be derived from other factual assertions. He draws attention to the following remark by Hume: Namely, “When you say that any act or quality is evil, it merely signifies that you have a feeling or emotion of blame or contempt towards it, which arises from your nature.” Hunter interprets this remark as a factual statement about human emotion, and such factual statements describe a causal connection between the observation of a specific act or quality and the feeling it evokes.
Ultimately, according to Hunter’s interpretation, Hume’s deontic proposition cannot be derived from specific ontological propositions—that is, propositions concerning the relations of reason or the objects of independent duty—but it can be derived from ontological propositions as factual statements concerning human emotions. According to this position, if moral judgments are descriptions of emotions, they can be either true or false, and consequently, they can yield moral knowledge. This holds true even if the content of such knowledge is subjective.
Conversely, Flew and Hudson, criticizing MacIntyre and Hunter’s interpretation of Hume, argue that Hume viewed moral judgments not as factual statements about human sentiments, but as expressions of sentiment. If Flew and Hudson are correct, Hume would be understood as a direct precursor to sentimentalism. Emotionalism, like Hume, distinguishes between the description of facts and the expression of emotions, regarding moral judgments as emotional expressions of approval or disapproval. From this perspective, moral judgments possess only emotional meaning; they merely express the speaker’s attitude and cannot be derived from descriptions of facts. Therefore, emotionalism asserts that moral arguments cannot be valid and that moral knowledge cannot exist. If moral judgments are merely expressions of sentiment, they cannot be true or false; at best, they can only be honest or dishonest. Ultimately, according to Flew and Hudson, Hume can be interpreted as an emotivist who denied the derivation of ought-statements from is-statements and asserted the impossibility of moral knowledge.
