Adam Smith is best known for being the father of modern economics with the publishing of his magnum opus The Wealth of Nations. Far fewer people know about his second most famous book (which, incidentally, is where the term “invisible hand” actually comes from). While the book is nominally about moral philosophy, I think it would be more accurately described as a work of psychology: Smith is trying to explain how morality arises from the workings of our minds. Much in the same way that The Wealth of Nations still seems surprisingly insightful today, I posit that A Theory of Moral Sentiments accurately described aspects of human psychology that were not appreciated until much later. I enjoyed listening to the on ToMS as well, if you want to have a lively discussion with lots of background and historical context.
[Editor's note: this is only a partial summary of the book, consisting of the first five out of seven parts of the book. I believe this covers the bulk of his theory, as the sixth chapter acts as something of a restatement of the previous sections, and was added in a later edition, and the seventh chapter is about comparing his moral philosophy to that of other thinkers of the day. I will also note that this was one of the very first book summaries I did, dating back at least three and a half years, so the style is quite different from the ones I'm writing today. Without further ado...]
Part I: Of the Propriety of Action
Section I: Of the Sense of Propriety
Chapter I: Of Sympathy - Smith posits sociability from the beginning; sympathy is the result of our mental model of others, of putting ourselves in their shoes, which is ultimately a product of our own perceptions and imagination, meaning they do not necessarily correspond to those we are sympathizing with. Our sympathy can thus be entirely illusory, for instance sympathy with the dead.
Chapter II: Of the Pleasure of mutual Sympathy - Once again, Smith basically posits that we want our sentiments to coordinate, and that this provides happiness even with negative sentiments (wherein sympathy is all the more important).
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 - The title says it all, the degree to which our sentiments correspond will determine sympathy, which in turn drives our sense of propriety. We judge the actions of others both on the motivating cause as well as the effect it produces, and the measure by which we judge others is our own sympathetic reaction to their sentiments.
Chapter IV: The same subject continued - Smith differentiations between sentiments regarding things unrelated to our situation, and those particularly affecting us. The former is essentially reserved for the objective world, and correspondence to (our perception of) reality is the measurement by which we judge the sentiments of others, but disagreement is largely tolerated. The latter involves our particular situations, which have a personal impact on us, and here a lack of sympathy is taken personally. The lack of knowledge about the particulars of each person’s situation result in an imprecise mental model, a discordance of sentiments, which causes our sympathetic response to be less than the feelings they actually experience. They also realize this, since they view themselves as an external observer would view them (the impartial spectator), and thus they temper their emotional response to fit the observers. (Note that this sets up a sort of give-and-take, that both parties have some responsibility to meet the other part way in seeking concordance of sentiments.) The degree of separation determines how much knowledge is shared knowledge, and thus we compose ourselves most around strangers and least around our closest friends.
Chapter V: Of the amiable and respectable virtues - Smith distinguishes between virtue and propriety. Virtue is essentially a superhuman effort. There are two types of virtue: amiable virtues are those of the spectator who enters into the sentiments of another to an extraordinary degree, the awful/respectable virtues are those of the person principally concerned to exercise extraordinary self-restraint in expressing their passions. In some cases, such as eating when hungry, perfect propriety requires effort that every human being can express, and thus it is not particularly virtuous. There can also be considerable virtue even when perfect propriety is not attained, if one approaches nearer to perfection than can commonly be expected.
Section II: Of the Degrees of the different Passions which are consistent with Propriety - As already stated, the spectator can never feel the same violence of passion as the observed, but the discrepancy will vary by the type of passion. Sympathy seems to be entirely dependent on the spectator’s ability to recreate the emotion in himself through his visualization of being another, which is difficult for particular cases. Throughout this section I can’t help but feel that many of Smith’s assertions are based upon his particular culture, and don’t necessarily generalize, but I am not sure that invalidates much of his work. (Klein states in the podcast that Smith is essentially sharing with us his own sensibilities.)