He also questions why particular causes must have such particular effects, and why is an inference drawn from one to the other. The statement that whatever has a beginning has also a cause of existence is not implied by any of the relations of resemblance, proportions in quantity and number, degrees of any quality, or contrariety; therefore, it is not able to be refutable using reason. Using that logic states that everything that exists must have a beginning, thus needing a cause. If it didn't have a cause then it would have had to produce itself, and that logic would mean that it had to exist before it existed. That argument contradicts itself, because it uses itself as a cause for existence in its premise, when it is proving the concept of cause being a necessity. Therefore, it begs the question to prove cause and effect by relying on the conclusion to prove the premise. .
The ideas of cause and effect cannot vary too far from actual impressions of the mind or ideas from the memory. We must first establish the existence of causes before we can infer effects from them. We have only two ways of doing that, either by an immediate perception of our memory or senses, called impressions, or, by an inference from other causes, called thoughts. For example, "A man finding a watch or any other machine in a desert island would conclude that there had once been men in that island" (160). Regardless of the source of the impression, the imagination and perceptions of the senses are the foundation for the reasoning that traces the relation of cause and effect. The inference that we draw from cause to effect does not come from a dependence on the two concepts to each other or from a rational objective look at the two. One object does not imply the existence of any other. All distinct ideas are separable, as are the ideas of cause and effect. The only way that we can infer the existence of one object from another is through experience.
