Hume’s Critique of Causal Relationships
By Josh Peete

Primary Source: An Enquiry Concerning Human Understanding by David Hume

David Hume, in An Inquiry Concerning Human Understanding, discusses how we cannot predict the future. Even though our experiences and our reasoning tell us that
objects act in a predictable way, we still cannot prove how objects will act in the future based upon previous interactions. After biting into a piece of pizza we expect an enjoyable taste. This enjoyable taste is expected because our past experiences have proven this to us. Even though we think we can predict that the pizza will act the same as our previous experiences, it may just blow up upon biting. Hume explains that there is no way to predict the future based on our previous experiences and reasoning and I will explain the logic he uses to prove this.

To start, Hume makes the distinction that humans’ relationships with objects are either relations of ideas or matters of fact. “All the object of human reason or inquiry can naturally be divided into, relations of ideas and matters of fact.”(499) Lets discuss these one at a time.

Relations of ideas are parts of knowledge that are a priori, or not learned by experience. “Propositions of this kind are discoverable by the mere operation of thought, without dependence on what is anywhere existent in the universe.”(500) So geometry would be put in this category because of the relationship between lines and figures. The opposite this type of knowledge is logically impossible. The example of how a square can never be a circle shows how the opposite of these claims do not make sense. Now that this distinction is made, we can move to discussing matters of fact.

Matters of fact are parts of knowledge that are a posteriori, or learned through experience. An example of a matter of fact is that my name is Josh Peete. I could have been named something else like John Doe and I still would be the same object. “The contrary of every matter of fact is still possible, because it can never imply a contradiction and is conceived by the mind with the same facility and distinctness, as if ever so conformable to reality.”(500) So the opposite of a matter of fact can be true. The piece of pizza that I bite into could explode in my face even though I had never experienced that before. Matters of fact, or knowledge learned through experience, cannot prove how objects function.

People believe in matters of fact because they have some other reason for doing so. “All reasoning concerning matter of fact seems to be founded on the relation of cause and effect. By means of that relation alone we can go beyond the evidence of our memory and senses.”(500) I have a firecracker and a lighter. The cause for the firecracker to explode would be me lighting the fuse. The effect of me lighting the fuse would be that the firecracker explodes. These claims are called causal claims and they explain the cause and effect relationships of objects. Hume uses the example of someone on a desert island who finds a watch. The person on the island concludes that the effect of a watch being on the island is a cause of a human once inhabiting it. His reasoning though may be wrong; he just uses prior experience to adopt the conclusion.

Cause and effect relationships are learned through experience. “That the knowledge of this relation is not in any instance, attained by reasoning a priori, but arises entirely from experience when we find that any particular objects are constantly conjoined with each other.”(500) There is a new yellow substance that I have never seen or experienced before and it is called yallerban. After looking at yallerban for a few hours I start to wonder the cause and effect of this substance. I can hypothesize all day as to what this substance does but there is no way for me to know without experiencing it. Though our senses, we as humans are unable to determine the effect of objects or the cause, which created it.

All human knowledge is either a relation between ideas, which are a priori, or matters of fact, which are a posteriori. Causal claims explain the relationship between an objects cause and effect. Neither by a relation between ideas, or by matters of fact are we able to prove causal claims. Therefore, we do not have any knowledge of causal claims and because of this, we cannot predict how objects will act in the future.


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