“…That these principles serve to connect ideas will not, I believe, be much doubted. A picture naturally leads our thoughts to the original: the mention of one apartment in a building naturally introduces an enquiry or discourse concerning the others: and if we think of a wound, we can scarcely forbear reflecting on the pain which follows it. But that this enumeration is complete, and that there are no other principles of association except these, may be difficult to prove to the satisfaction of the reader, or even to a man’s own satisfaction. All we can do, in such cases, is to run over several instances, and examine carefully the principle which binds the different thoughts to each other, never stopping till we render the principle as general as possible. The more instances we examine, and the more care we employ, the more assurance shall we acquire, that the enumeration, which we form from the whole, is complete and entire.”
Indeed, it would be very difficult to prove that Resemblance, Contiguity, and Cause and Effect are the complete list of the principles of association. How could we, for instance, based only on those principles, build the complex idea of Pythagoras’ theorem? How could we build Galileo’s principle? Hume was very smart when he admitted that he could not prove the completeness of his list.
But let’s look at the details: simple ideas are continually there, at least hypothetically, in our understanding, isolated from each other. Those simple ideas are what Hume calls “impressions”, and are distinguished from those other “perceptions” that Hume calls “ideas” in that they are more “lively”. But, what does “lively” mean? Does it mean that while impressions produce strong
effects on us (sensations, feelings, emotions…), ideas produce just dull
effects? If simple ideas are, by themselves, isolated from each other, how is it that they can
affect us?
Anyway, Hume suggests that we continually make associations between the simple ideas that emerge in our conscience. So,
we produce complex ideas; we are the cause of complex ideas.… But, isn’t this an indication that “Cause and effect” is a peculiar principle of association which has to be distinguished from Resemblance and Contiguity, because it is not only an epistemological principle, but an ontological one: When our “understanding” associates ideas (either simple or complex already) by Resemblance or Contiguity, isn’t “Cause and effect” immanent there? Yes, it is there, precisely because our “understanding” is producing the complex ideas.
So, according to Hume, “Cause and Effect” is one of our principles of association that the “understanding” applies to impressions in order to form complex ideas; but he wants to know more, he wants to investigate how do we arrive at the knowledge of this principle. Here you can read his own words:
“…we must enquire how we arrive at the knowledge of cause and effect. I shall venture to affirm, as a general proposition, which admits of no exception, that the knowledge of this relation is not, in any instance, attained by reasonings a priori; but arises entirely from experience, when we find that any particular objects are constantly conjoined with each other.”
Evidently this general proposition, which according to Hume admits of no exception, was not obtained by reasonings a priori either; which implies that Hume believed there are propositions which are not obtained a priori and still are universally valid. Therefore, if he believed that the principle of “cause and effect” did not have universal validity just because it is not obtained by reasonings a priori, he was inconsistent.
Now, what does Hume mean when he says that “cause and effect” is known by experience? Is he speaking about the principle of causality or about particular cases of this principle. Let’s him explain:
“This proposition, that causes and effects are discoverable, not by reason but by experience, will readily be admitted with regard to such objects, as we remember to have once been altogether unknown to us; since we must be conscious of the utter inability, which we then lay under, of foretelling what would arise from them. Present two smooth pieces of marble to a man who has no tincture of natural philosophy; he will never discover that they will adhere together in such a manner as to require great force to separate them in a direct line, while they make so small a resistance to a lateral pressure. Such events, as bear little analogy to the common course of nature, are also readily confessed to be known only by experience; nor does any man imagine that the explosion of gunpowder, or the attraction of a loadstone, could ever be discovered by arguments a priori. In like manner, when an effect is supposed to depend upon an intricate machinery or secret structure of parts, we make no difficulty in attributing all our knowledge of it to experience. Who will assert that he can give the ultimate reason, why milk or bread is proper nourishment for a man, not for a lion or a tiger?”
So, he is speaking about cases of the principle, not about the principle, and I won’t argue that Hume is wrong on this.
I do not intend to say either that the principle of causality is obtained a priori. In several occasions I have said it is not. I just want to remark something which should be obvious: we can ignore what is the cause of a given phenomenon, but it does not mean that we will be uncertain if it has a cause or not.
But Hume had more to say…
Continues…
