Hume, D. (1896) A Treatise of Human Nature, Book I, Part III, sections ii and xiv. Urbana, Illinois: Project Gutenberg. (Original work published in 1739)
Hume’s methodology for the analysis of Causality is to understand what we mean when something is a cause, and what is the origin of causality (where did we get that idea of causality from?).
Hume’s epistemology = Hume is an empiricist. Understanding the ideas we possess involves tracing them to their origins of experience.
Empiricism = the view that all knowledge originates in experience (sensory experience + experience of our internal processes aka mental lives). All knowledge is a posteriori.
For Hume,
- idea = concept
- impression = sensory and/or inner experiences that gives rise to those ideas.
Summary of Hume’s work and Legacy
According to Hume’s two definitions of causation, cause and effect are objects or events that seem to go together, with regularity, in repeated instances of the world. Objectively speaking, causes and effects are constant conjunctions of objects or events. The second point is that causality involves necessary connections between conjoined objects or events.
Hume’s work is one of the most influential work for the philosophy of Causality developing Humean (or neo-Humean) theories.
The first point of regularity gives us the notion of causal generalization = broad, law-like statements that describe a regular connection between cause and effect. The second point of necessity leads to the idea of causal necessity— but for Hume, this is a projection of the mind, formed by habit, not something we perceive in this world.
IN OTHER WORDS, Humean theory of causation (regularity + necessity) gives a law-like picture of causation.
- universal generalization “Every B-like thing always follow from every A-like thing”
- causal necessity “Events of type B necessarily follow from events of type A”
Some philosophers reject Hume’s anti-realism and argue that causal necessity is part of objective reality. There is an objective relationship between cause and effect that involve necessity.
According to Humean causation, singular causal claims presupposes:
- the existence of a general law
- that the individual case is an instance of that general law
- (if necessity is objective) that the connection is necessary
Main points from the reading
Hume begins by telling us that the idea of causation cannot be found in any of a particular’s qualities. According to Hume, causality isn’t an intrinsic quality, but rather, it is a relation that holds among objects.
The three relations of causation
Hume describes causation as several relations packed into one:
1. relation of contiguity
“I find in the first place, that whatever objects are consider’d as causes or effects, are contiguous; and that nothing can operate in a time or place, which is ever so little remov’d from those of its existence.”
Hume is explaining that two objects considered as cause and effect will be close together, both in time and in space. There is no cause that can be a distance away from its effect; there must be some kind of contact in space at a given time.
Even if distant objects seem to be causally related, Hume asserts that this is kind of an illusion:
“they are commony found on examinatio to be linked by a chain of causes, which are continguous among themselves …“
2. relation of priority in time
This notion explains that a cause always, in some sense, must precede its effect.
This can be seen as controversial since for certain causal processes, this might not seem true. It could be argued that fire and the smoke pluming out of it occur at the same time; for Hume, it is plausible to suppose that the cause has to take place first in order to start the effect — there would be no smoke if there was no fire.
“For if one cause were co-temporary [that is, simultaneous] with its effect, and this effect with its effect, and so on, ‘tis plain that there wou’d be no such thing as succession, and all objects must be coexistent.”
Hume asserts that without the relation of priority in time (if cause and effects were simultaneous), there would be no change. So, there can’t be simultaneous causation; causes must precede effects.
When we visually see a causal interaction, we see the continuity and priority of the cause and effect via sensory experience.
3. relation of necessary connection
causal necessity
“An object may be contiguous and prior to another, without being consider’d as its cause. There is a NECESSARY CONNEXION to be taken into consideration; and that relation is of much greater importance, than any of the other two above-mention’d.”
As Hume explains it, causes are necessarily connected to their effects; the effect is necessary as a consequence (if the cause occurs, the effect must occur).
Impressions of necessary connections =
- the idea of necessary connection doesn’t come from our impressions of the qualities of individual objects, or the observable relations between objects
- Hume observes that we would never arrive at the idea of causal neccessity if we only ever saw single instances of cause and effects (only ever saw fire causing smoke once). Only from repeated instances of similar conjunctions do we form the idea of neccessary connection, and “begin to draw an inference from one to the other”
This develops Hume’s argument: the idea of causal necessity doesn’t derive solely from the sensory experience of conjoined objects. Instead, the repetitions condition the mind to add something of its own. The repetitions lead us to expect the conjoined effects when we perceive the causes, or the conjoined causes when we perceive the effects.
- e.g.: The repetitions lead us to expect that the next time we see a fire, there will be smoke billowing from it.
In other words, neccessary connection = the expectation or habit our minds have a tendancy to form when exposed to repeating pairings of cause and effects. (whenever A occurs, B will follow)
Hume calls this:
” … [Neccessity] is nothing but an internal impression of the mind, or a determination to carry our thought from one object to another”
Hume gives a subjective account of, what he considers to be, the most crucial component of causality.
Anscombe’s argument against causal necessity
Link to original
Two Definitions of causation
Definition 1 =
“[A cause is] an object precedent and contiguous to another, and where all the objects resembling the former are plac’d in like relation of precedency and contiguity to those objects, that resemble the latter.”
By this definition, to call “fire the cause of smoke” is simply to say “the occurrence of fire is regularly followed by the occurrence of smoke.”
This definition leaves out the mention of necessary connection entirely, and describes cause-effect pairing in terms of contiguity and temporal priority. It reduces causation to mere regularity.
Definition 2 =
“A cause is an object precedent and contiguous to another, and so united with it, that the idea of the one determines the mind to form the idea of the other, and the impression of the one to form a more lively idea of the latter.”
On this definition, the identification of cause and effect is, in a sense, a projection of our own mental processes — it does not exist objectively in the world.
Definition 1 gives the external impressions, while definition 2 gives the internal impressions. Combining the two gives the full picture of Hume’s theory of causation.
Hume’s stance on realism and anti-realism
Hume’s stance on realism or anti-realism about causality depends on which definition of Hume’s we emphasis on.
Hume’s Definition 1 gives a realist account of Causality, but definition 2 tthat incorporates mind dependent necessary connections between causes and effects gives an anit-realist account as it involves the projection of some feature of our minds.