Overview

Hume starts Section 5, titled “Skeptical Solution of These Doubts” with some reflections on what he has shown. In the readings from last time, we saw that he thinks he has shown that we have no reason for believing anything based on inductive inferences, that is, we have no reason to believe inferences about the future based on our observations of the past.¹ So does he think we should stop trying to make such inferences or that we should stop believing them?

He does not. Instead, he describes himself as having an “Academic or skeptical philosophy” which involves “renouncing all speculations which lie not within the limits of common life and practice” (Hume [1748] 2019, 594R). For example, we should suspend judgment about whether the mind is material or immaterial (see Hume [1739] 2019, 571).

Fine, but what about inductive inference? Hume thinks that we could not give it up even if a philosophical argument showed it was baseless.

Nature will always maintain her rights, and prevail in the end over any abstract reasoning whatsoever. Though we should conclude, for instance, as in the foregoing section, that, in all reasonings from experience, there is a step taken by the mind, which is not supported by any argument or process of the understanding, there is no danger, that these reasonings, on which almost all knowledge depends, will ever be affected by such a discovery. (Hume [1748] 2019, 595L)

The interesting question, as Hume sees it, is why the mind takes the step of drawing inductive inferences. If reason does not lead us to do this, what does?

Now, before we get into the nitty gritty, you might have noticed a shift between one sort of point and another. Hume started out by describing his philosophy as one that urges us to suspend judgment about certain questions. So understood, it is normative: it recommends that we do or think something. But the project Hume engages in is descriptive: it involves explaining why we draw inductive (or causal) inferences. It seems to me that this is something that Hume wrestled with. What is the point of clever arguments that lead to conclusions that no one can live with? It’s a good question!

The Skeptical Solution

Hume is skeptical about our ability to understand the relationship between cause and effect. But, obviously, we do think that there is such a thing as causal relations. Why?

His answer is custom or habit drives us to think that one thing causes another.

The central argument for this position is that we cannot make causal inferences based on a single observation. Rather, we have to observe that “similar objects and events” are “constantly conjoined” (Hume [1748] 2019, 595L).

Belief

In the second part of Section 5, Hume takes up Anjali’s question about Berkeley: if everything is an idea in our heads, how do we distinguish between things that we believe to be true and things that we imagine without believing?

Hume maintains that belief is a feeling that is associated with an idea: “belief is nothing but a more vivid, lively, forcible, firm, steady conception of an object, than what the imagination alone is ever able to attain” (Hume [1748] 2019, 598L).

Here are three questions for discussion.

1. How is that story connected to the claim that belief is a kind of feeling?

2. Can we say more about what belief is? We can talk about how belief is different from imagination: how does believing that something is so differ from imagining something to be so? We can also consider how believing something is so is different from wanting it to be so.

3. How does this work in a case where there is conflicting evidence? Or when the “conjunctions” are not uniform? See the last paragraph in Section 6 (Hume [1748] 2019, 602).

Necessary Connection

The task for Section 7 is “to fix, if possible, the precise meaning of these terms,” namely, “power, force, energy or necessary connexion” (Hume [1748] 2019, 603). These are all terms surrounding causation: causes have the power to bring about their effects, they force their effects to happen, they have the energy to produce their effects, and they make their effects necessary. For Hume, these are all different ways of saying that there is a necessary connection between cause and effect.

Why is this obscure? Why do we need to fix the meaning of these ideas? As we have seen, Hume is committed to the doctrine that every idea is separable from every other idea. That is why you cannot come up with a demonstrative proof that one tennis ball will make the other one move when it strikes it. It is always possible that the second ball will not move in the expected way.² So the search for a necessary connection between cause and effect is the search for a kind of link between two things that, according to Hume, either cannot exist at all or that we cannot understand. (Scholars are divided between those two interpretations; I favor the second myself, for what it is worth.)

Hume goes through three possible ways of discovering the power that causes have to make their effects necessary.

1. Do we find necessary connections between causes and effects in a single instance of cause and effect between external objects? (Hume [1748] 2019, 603R–604L).

2. Do we find necessary connections between mind and body, when an act of will causes the body to move? (Hume [1748] 2019, 604R–605L)

3. Do we find necessary connections among the ideas in our mind when we decide to think about something? (Hume [1748] 2019, 605R–606)

The first part of Section 7 ends with an extended critical discussion of Malebranche. Hume notes that Malebranche has diagnosed the same problem that he has: we cannot find a necessary connection between causes and effects in either the material world or the mental one. But Malebranche’s solution, in Hume’s opinion, is subject to two objections that he gives in the last two paragraphs of part 1 (Hume [1748] 2019, 607–8).

In the second part, Hume uses his theory that causal inferences are the product of customs or habits formed after the experience of constant conjunctions of types of causes and types of effects to explain what our idea of the necessary connection between cause and effect is.

Here are some questions for discussion.

1. How does Hume distinguish between causation and correlation? Or, perhaps better, does Hume distinguish between causation and correlation?

2. What do we think of the definitions of “cause” given on page 609R? (Look for the italics) On the face of it, they are quite different. How would you characterize the difference between them? Any speculations about why Hume thought they were essentially the same are welcome!