Reason and Morality

Class notes for 17 February

Main points

Hume observed that we make moral distinctions. Morality, broadly speaking, concerns the assessment of people as good or bad, and, narrowly speaking, how they treat other people.

He asked how we do so and why we think that people are good or bad. In particular, he attempted to show that we use the passions, and not reason, to make moral distinctions: “virtue is distinguished by the pleasure and vice by the pain, that any action, sentiment, or character gives us by the mere view and contemplation” ( He subsequently insisted that character is the primary thing we assess and that we judge actions good or bad only insofar as they display good or bad motives or character traits (

I found it useful to group Hume’s arguments into thee classes:

  1. Those that turn on general points about the relationship between reason and action; these are relevant because the thought that an action would be wrong or bad can lead someone not to do it and so moral distinctions, whatever they are, must be capable of causing action.
  2. Reason is too broad: errors in morality are unlike errors of reason.
  3. Arguments against demonstrative and probable reasoning.

The first involve repeating charges made in Book 2; the notes for that day’s class cover the relevant material (which was discussed on both days).

Reason is too broad

The second points out that moral errors are treated differently than errors about demonstrations or matters of fact. No one thinks that the person who commits an error in mathematics is bad, for example.

Hume’s argument turns on characterizing errors of reasoning as involuntary and unavoidable ( As Katie pointed out, that sounds like an odd thing for someone with Hume’s position about free will to say. I agree. I think Hume would probably try to defend himself by saying that there is rarely a motivation for errors of reasoning and our beliefs about vice and virtue are, again, about people’s characteristic motivations. I leave for others to decide whether that would fend off Katie’s charge.

Demonstrative & probable reasoning

The third point largely involves a discussion of demonstrative reasoning. For example, Hume points out that an oak tree might have the same relationship to its parent as a human being who commits parricide. The fact that we don’t think the oak tree did anything wrong is supposed to show that we don’t come to believe that things are wrong by considering relations among them and, thus, that we don’t employ demonstrative reasoning in making moral distinctions.

The section ends with a quick discussion of the other kind of reasoning, probable reasoning or reasoning about matters of fact. Hume says that the previous arguments apply here and adds a couple of compressed, famous paragraphs:

The first of these has launched several interpretations, much like the famous passage concerning necessary connection ( — also paragraph 27, eerie). It is far from clear that Hume thought through the implications of what he wrote here in nearly the details that subsequent readers have attributed to him.

For example, Hume suggests that what we mean when we call something good or bad is that we have a pleasurable or painful feeling. He also proposes an analogy with secondary qualities: we think that things are good or bad much as we think they have colors, even though, in both cases, we are simply projecting a feature of our thoughts onto external objects. Obviously, these two suggestions are in tension with one another. When I say that a war was unjust, either I mean to say something about myself (that I have a bad feeling) or I mean (albeit in a mistaken way) that the object, the war, is bad. It’s hard to see how I could mean both.

Hume adds a point about ontology (what sorts of things exist): there are no good or bad qualities of objects for our thoughts to be true or false about (and passions don’t represent qualities of objects anyway). As Adi pointed out, there seems to be an important difference between morality and necessary connections between causes and effects. Hume was willing to admit that there might be something corresponding to our belief about necessary connections, some reason why causes bring about effects. But there is no such concession in the case of morality: it is based in us and not found in world as it is anyway, without us.

Epistemology (how we know) and psychology (how our minds work), for those keeping score (see “MOPE” in the syllabus) come elsewhere in this section. By “psychology,” I mean his claim that reason alone cannot cause action and that passions must be involved: that is a point about how our minds work in causing action. By “epistemology” I mean that his position could be taken to be about how we know what is good and what is bad: we use our passions and not reason.