Hume on Cause and Effect
An analysis of arguments given by David Hume for denying the necessary connection between cause and effect
Introduction
The British empiricists of the Early Modern period, like David Hume, John Locke and George Berkeley are all popular for advocating the view that all knowledge comes from experience and that innate ideas do not exist. Hume took this concept and applied it meticulously to necessity and causation.
Cause and Effect
In his work ‘The Treatise of Human Nature’, Hume points out the three components associated with causation:
- Proximity of time and space
- Temporal priority of cause
- Necessary connection
The first two are clearly rooted in experience, but the third is not. This can be clarified with the help of the billiard ball example. In all past experiences of billiard, a stationary ball moves when struck with a moving one. The order in which this happens is also always the same. But the premise that the movement of the stationary ball is necessitated when being struck is not logically deduced. It is only derived from similar past observances. We never see it for ourselves.
Therefore, if we were to do away with the third component, i.e., necessary connection, we would have no reason to believe that a certain cause produces/produced a certain effect. The claim ‘The future will be like the past” is not logically justified.
Skeptical Solution
Hume claimed that the idea of necessary connection is derived from the sense of determination that a first event of a duo will be succeeded by the next as per past experiences. The idea that the second event is carried along after the first is being referred to here.
By this solution (explanation for the conception of necessary cause), the rationality (or lack thereof, as per Hume) is not, in any way, affected. It merely explains the psychological grounds for the belief.
Here, he makes a crucial point. He claims that we are driven (more) by feelings, rather than by reason (and that this is not necessarily a bad thing).
“All inferences from experience, therefore, are effects of custom, not of reasoning.” — Hume
Causal Inference: Critical Phase
When one makes a causal inference, one admits that there exists a connection between present facts and what is being inferred from them. This connection of causal inference can be determined by the faculty of reason (which arises from matters of facts-based on experience ,and relations of ideas-scientific propositions).
Read David Hume on the Problem of Induction to understand the context.
Hume interjects here and says that such a connection cannot be derived from relation of ideas. As events, the effect is distinct from the cause. So it is not unconceivable for one to occur without the other. But this is often overlooked because of intuition of co-occurrence (which is psychological).
Further, Hume points out that a-priori reasoning does not lead to the formation of the idea of causation (or cause and effect relation) as it only involves ideas (and not observation) of objects. Therefore, the idea of necessary connection does not have its roots here. This was in opposition to what thinkers in that age commonly believed.
The Future Will Be Like The Past
Next, he considers the possibility of causal inferences being derived from experience or matters of fact. When one has experienced the constant conjunction of two events in every instance of past, one tends to think of them as being cause and effect respectively. This inference is drawn not from reason. It should be noted, Hume believes, that such experiences only give us information about what has already occurred, and not about what is going to occur. Hence, they are not to be confused with being causal inferences as those also predict future occurrences on the basis of past experience.
Just because pain killers have relieved one’s pain in the past does not mean that they will continue to do so in the future. Hume highlights the gap in reasoning between these two propositions. While the first summaries what has happened in the past, the latter predicts what will happen in the future. The link between the two is not, in any distinct way, established (the necessary connection us missing). A change in the course of nature is not contradictory and cannot be falsified by reasoning with relations of ideas.
Probable Reasoning
After eliminating other possibilities, we are left with probable reasoning. Hume eliminates this by pointing out that such reasoning is circular, and hence fallacious. If we attempt to infer an effect from a cause, we would be implying that there exists a necessary connection (hence making the two cause and effect respectively).
With this, means of justifying the principle of necessary connection come to an end. Even though this leads to skepticism, that is not necessarily a bad outcome, as Hume says that skeptical doubts are not necessarily a discouragement but rather an encouragement to find something more satisfactory.
Thoughts
The Treatise of Human Nature, for me, was one of those philosophical texts that, through the astonishing power of good argumentation make you question things you thought to be fundamentally true and necessary (which I think is the trademark of great philosophical texts). Hume’s skepticism about causation and the reasons he gave for it were very convincing. Ultimately, after acknowledging all the defects in the theory of causation, he contends that we must continue to believe it even though we do not have rational grounds for doing so. Here, his crucial point comes out — that we are driven more so by passion/feeling than by reason. A belief in causation comes intuitively to us and disbelieving it would make it really hard to go about with daily life.
Conclusion
Because we cannot observe causation, we have no rational grounds to believe in it, says empiricist Hume. He points out that experience is not a reliable guide. Claiming that ‘A is the cause which results in B that is the effect’ is the same as saying ‘Because of the constant conjunction of A and B, one is psychologically assured that B follows from A’.
This realization of the gap of necessary connection gives rise to Hume’s popular problem of induction.
Also read — David Hume on the Problem of Induction and Response to Hume’s Problem of Induction
