Moral philosophy background

Class notes for 17 February

Main points

Important points in Hume’s moral philosophy involve responding to his contemporaries. Today’s class was devoted to exposing two of the more important lines of thought about morality that Hume had in mind.


Hobbes is what I called an egoistic authoritarian conventionalist. Or, more accurately, he was taken to be one; he was certainly close enough for our purposes.

People are motivated only or predominantly by self-interest.
A kind of problem can only be solved by a human authority who stipulates and/or enforces a solution.
A certain area of thought depends on social conventions, rather than reflecting the way things are independent of social interaction.

Hume, like Hobbes, thought that self-interest played an important role in an important part of morality: the artificial virtues, such as justice. But he denied that people are predominantly self-interested as his account of the natural virtues shows. Hume was also a conventionalist concerning justice but he did not think that the relevant conventions depend on authority.


Samuel Clarke is a rationalist: he held that there are eternal fitnesses and unfitnesses of things whose discovery by reason tells us what to do. (He also had some sharp criticisms of Hobbes that Hume seems to have avoided in his own conventionalist theory).

I said that I thought that Clarke was right to say that good and evil are logically contradictory but that he was too hasty in concluding that it follows that they are not based on features of human nature (or God, for that matter).

After all, people may agree that good and evil are contraries but still disagree about what counts as good and evil. Of course, people disagree about mathematics too. But there is a method of demonstration in mathematics that has no obvious parallel in morality.

I took special pains to flag some material near the end of the Clarke reading: his assertions that human beings are made in the image of God and that reason is the faculty that makes us like God in our liberty and our knowledge of what to do. See Clarke, pp. 91, 62-3, 66, and 85. That is the view of human beings that Hume set out to undermine.


In the course of discussing Clarke, we fell into a brief discussion of the nature of numbers. Don’t ask how. And don’t ask for answers. Well, don’t ask me. But you could ask Megan, Heidi, and Patricia Blanchette, of Notre Dame University, who, collectively offered the following resources for pursuing these issues. (Well, I added one very small tidbit).

  1. A radio program on numbers (Odyssey, on our very own WBEZ).
  2. Christian Goldbach (1690-1764) was born in Konigsburg, Prussia and became a professor of mathematics at the Imperial Academy of St. Petersburg. His conjecture — that every even number greater than 2 can be expressed as the sum of two primes — was first expressed in a letter to Leonard Euler (1707-1783). Euler, by the way, was the most prolific mathematician ever. No one has disproven Goldbach’s Conjecture, but no one has proven it either.
  3. In general, a good place to find answers to math questions is, but most of the entries are written for a somewhat mathematically-inclined audience. For the historically inclined, St. Andrews University’s MacTutor History of Mathematics archive is the place to go.
  4. For a philosophical discussion of realism about numbers, a good place to start is with Paul Benacerraf’s two articles, “Mathematical Truth” [JSTOR] and “What Numbers Could Not Be.” [JSTOR]. JSTOR requires a University of Chicago internet connection. These articles are also reprinted all over the place; the first, for example, is in Dale Jacquette’s Philosophy of Mathematics anthology (Blackwell). A classic anthology that’s always worth looking through is called Philosophy of Mathematics, edited by Benacerraf and Putnam.