The Theory of Moral Sentiments is a 1759 book by Adam Smith.Letter from David Hume to Adam Smith, 12 April 1759, in Hume, D. (2011) New Letters of David Hume, ed. Raymond Klibansky and Ernest C. Mossner, Oxford: Oxford University Press. p. 49.; It provided the ethical, philosophical, economic, and methodological underpinnings to Smith's later works, including The Wealth of Nations (1776), Essays on Philosophical Subjects (1795), and Lectures on Justice, Police, Revenue, and Arms (1763) (first published in 1896).

Sympathy Smith departed from the "moral sense" tradition of Anthony Ashley-Cooper, 3rd Earl of Shaftesbury, Francis Hutcheson, and David Hume, as the principle of sympathy takes the place of that organ. "Sympathy" was the term Smith used for the feeling of these moral sentiments. It was the feeling of understanding the passions of others. It operated through a logic of mirroring, in which a spectator imaginatively reconstructed the experience of the person he watches:Smith, Adam (1872). Black, Joseph; Hutton, James (eds.). The Essays of Adam Smith (6 ed.). London: Alex. Murry & Co. p. 9. Retrieved 21 Jan 2021.

As we have no immediate experience of what other men feel, we can form no idea of the manner in which they are affected, but by conceiving what we ourselves should feel in the like situation. Though our brother is on the rack, as long as we ourselves are at our ease, our senses will never inform us of what he suffers. They never did, and never can, carry us beyond our own person, and it is by the imagination only that we can form any conception of what are his sensations. Neither can that faculty help us to this any other way, than by representing to us what would be our own, if we were in his case. It is the impressions of our own senses only, not those of his, which our imaginations copy. By the imagination, we place ourselves in his situation...

However, Smith rejected the idea that Man was capable of forming moral judgements beyond a limited sphere of activity, again centered on his own self-interest:

The administration of the great system of the universe ... the care of the universal happiness of all rational and sensible beings, is the business of God and not of man. To man is allotted a much humbler department, but one much more suitable to the weakness of his powers, and to the narrowness of his comprehension: the care of his own happiness, of that of his family, his friends, his country.... But though we are ... endowed with a very strong desire of those ends, it has been entrusted to the slow and uncertain determinations of our reason to find out the proper means of bringing them about. Nature has directed us to the greater part of these by original and immediate instincts. Hunger, thirst, the passion which unites the two sexes, and the dread of pain, prompt us to apply those means for their own sakes, and without any consideration of their tendency to those beneficent ends which the great Director of nature intended to produce by them

The rich only select from the heap what is most precious and agreeable. They consume little more than the poor, and in spite of their natural selfishness and rapacity, though they mean only their own conveniency, though the sole end which they propose from the labours of all the thousands whom they employ, be the gratification of their own vain and insatiable desires, they divide with the poor the produce of all their improvements. They are led by an invisible hand to make nearly the same distribution of the necessaries of life, which would have been made, had the earth been divided into equal portions among all its inhabitants, and thus without intending it, without knowing it, advance the interest of the society, and afford means to the multiplication of the species.

In a published lecture, Vernon L. Smith further argued that Theory of Moral Sentiments and Wealth of Nations together encompassed:

"one behavioral axiom, 'the propensity to truck, barter, and exchange one thing for another,' where the objects of trade I will interpret to include not only goods, but also gifts, assistance, and favors out of sympathy ... whether it is goods or favors that are exchanged, they bestow gains from trade that humans seek relentlessly in all social transactions. Thus, Adam Smith's single axiom, broadly interpreted ... is sufficient to characterize a major portion of the human social and cultural enterprise. It explains why human nature appears to be simultaneously self-regarding and other-regarding."Smith, Vernon L. (1998). "The Two Faces of Adam Smith", Southern Economic Journal, 65(1), p. 3 (pp. 1–19..

The Theory of Moral Sentiments: Edition 6 Consists of 7 parts: Part I: Of the propriety of action Part II: Of merit and demerit; or of the objects of reward and punishment Part III: Of the foundations of our judgments concerning our own sentiments and conduct, and of the sense of duty. Part IV: Of the effect of utility upon the sentiments of approbation. Part V: Of the influence of custom and fashion upon the sentiments of moral approbation and disapprobation. Part VI: Of the character of virtue Part VII: Of systems of moral philosophy

Part I: Of the propriety of action Part one of The Theory of Moral Sentiments consists of three sections: Section 1: Of the sense of propriety Section 2: Of the degrees of which different passions are consistent with propriety Section 3: Of the effects of prosperity and adversity upon the judgment of mankind with regard to the propriety of action; and why it is more easy to obtain their approbation in the one state than the other

Part I, Section I: Of the Sense of Propriety Section 1 consists of 5 chapters: Chapter 1: Of sympathy Chapter 2: Of the pleasure of mutual sympathy Chapter 3: Of the manner in which we judge of the propriety or impropriety of the affections of other men by their concord or dissonance with our own Chapter 4: The same subject continued Chapter 5: Of the amiable and respectable virtues

Part I, Section I, Chapter I: Of Sympathy According to Smith, people have a natural tendency to care about the well-being of others for no other reason than the pleasure one gets from seeing them happy. He calls this sympathy, defining it "our fellow-feeling with any passion whatsoever" (p. 5). He argues that this occurs under either of two conditions: We see firsthand the fortune or misfortune of another person The fortune or misfortune is vividly depicted to us

Although, this is apparently true, he follows to argue that this tendency lies even in "the greatest ruffian, the most hardened violator of the laws of society" (p. 2).

Smith also proposes several variables that can moderate the extent of sympathy, noting that the situation that is the cause of the passion is a large determinant of our response: The vividness of the account of the condition of another person An important point put forth by Smith is that the degree to which we sympathize, or "tremble and shudder at the thought of what he feels", is proportional to the degree of vividness in our observation or the description of the event. Knowledge of the causes of the emotions When observing the anger of another person, for example, we are unlikely to sympathize with this person because we "are unacquainted with his provocation" and as a result cannot imagine what it is like to feel what he feels. Further, since we can see the "fear and resentment" of those who are the targets of the person's anger we are likely to sympathize and take side with them. Thus, sympathetic responses are often conditional on—or the magnitude for understanding another person is determined by—the causes of the emotion the person is experiencing. Whether other people are involved in the emotion Specifically, emotions such as joy and grief tell us about the "good or bad fortune" of the person we are observing them in, whereas anger tells us about the bad fortune with respect to another person. It is the difference between intrapersonal emotions, such as joy and grief, and interpersonal emotions, such as anger, that causes the difference in sympathy, according to Smith. That is, intrapersonal emotions trigger at least some sympathy without the need for context whereas interpersonal emotions are dependent on context.

He also proposes a natural "motor" response to seeing the actions of others: If we see a knife hacking off a person's leg we wince away, if we see someone dance we move in the same ways, we feel the injuries of others as if we had them ourselves.

Smith makes clear that we sympathize not only with the misery of others but also the joy; he states that observing an emotional state through the "looks and gestures" in another person is enough to initiate that emotional state in ourselves. Furthermore, we are generally insensitive to the real situation of the other person; we are instead sensitive to how we would feel ourselves if we were in the situation of the other person. For example, a mother with a suffering baby feels "the most complete image of misery and distress" while the child merely feels "the uneasiness of the present instant" (p. 8).

Part I, Section I, Chapter II: Of Pleasure and mutual sympathy Smith continues by arguing that people feel pleasure from the presence of others with the same emotions as one's self, and displeasure in the presence of those with "contrary" emotions. Smith argues that this pleasure is not the result of self-interest: that others are more likely to assist oneself if they are in a similar emotional state. Smith also makes the case that pleasure from mutual sympathy is not derived merely from a heightening of the original felt emotion amplified by the other person. Smith further notes that people get more pleasure from the mutual sympathy of negative emotions than positive emotions; we feel "more anxious to communicate to our friends" (p. 13) our negative emotions.

Smith proposes that mutual sympathy heightens the original emotion and "disburdens" the person of sorrow. This is a "relief" model of mutual sympathy, where mutual sympathy heightens the sorrow but also produces pleasure from relief "because the sweetness of his sympathy more than compensates the bitterness of that sorrow" (p. 14). In contrast, mocking or joking about their sorrow is the "cruelest insult" one can inflict on another person: To seem to not be affected by the joy of our companions is but want of politeness; but to not wear a serious countentance when they tell us their afflictions, is real and gross inhumanity (p. 14). He makes clear that mutual sympathy of negative emotions is a necessary condition for friendship, whereas mutual sympathy of positive emotions is desirable but not required. This is due to the "healing consolation of mutual sympathy" that a friend is "required" to provide in response to "grief and resentment", as if not doing so would be akin to a failure to help the physically wounded.

Not only do we get pleasure from the sympathy of others, but we also obtain pleasure from being able to successfully sympathize with others, and discomfort from failing to do so. Sympathizing is pleasurable, failing to sympathize is aversive. Smith also makes the case that failing to sympathize with another person may not be aversive to ourselves but we may find the emotion of the other person unfounded and blame them, as when another person experiences great happiness or sadness in response to an event that we think should not warrant such a response.

Part I, Section I, Chapter III: Of the manner in which we judge of the propriety or impropriety of the affections of other men by their concord or dissonance with our own