Hume’s discussion of causation can seem a detour from the pressing issues of theorising about the social aetiology of mental illness. But on the assumption, for the moment, that the social aetiology of mental illness concerns, as its etymology suggests, the causation of mental illness, it is central.
(There are two other ways we might think about social aetiology of mental illness. We might think of it as a constitutive claim in the spirit of Foucault or Laing. To be ill is constituted not caused by social factors. One is, for example, out of step with one’s culture. The other is that we might think of the social factors as playing a role in making mental illness understandable. If so, the role they play is not merely causal. These ideas will return in sessions 3 and 4.)
Hume’s sceptical discussion leads to his three definitions.
an object, followed by another, and where all the objects similar to the first are followed by objects similar to the second. (p76)
Or in other words where, if the first object had not been, the second never had existed. (p76)
an object followed by another, and whose appearance always conveys the thought to that other. (p77)
The first is the most influential: causation is an essentially general notion. No one event makes another happen but events of one sort are followed by events of the second.
The third definition points out the psychological underpinnings of Hume’s account. The impression of causation (which we seem to mistake for the impression of one thing making another thing happen) is really our experience of expectation, which we then project onto the world.
The second definition is distinct. It is a counter-factual conditional. That should prompt the question. What is the relation, if any, between 2, on the one hand and 1 and 3, on the other? Most philosophers since Hume have taken 1 and 3 to be fundamental and then used them to explain 2. But, as we will see next time, that requires that one can articulate the right kind of generality on which to base an account of causation: a regularity that sustains a counter-factual conditional.
We can use that property to mark out the class of laws of nature, but if so, how do laws support counter-factuals?
In sum, Hume pushes our understanding of causation from the individual to the general (though still leaving some problems at that level). This suggests that if social aetiology is a matter of causation (not understanding; not constitution) then it is a general matter. We should be looking not for one off relations of social factors leading to illness but to generalities.