What Came First: The Chicken or the Egg David Hume moves through a logical progression of the ideas behind cause and effect. He critically analyzes the reasons behind those generally accepted ideas. Though the relation of cause and effect seems to be completely logical and based on common sense, he discusses our impressions and ideas and why they are believed. Hume's progression, starting with his initial definition of cause, to his final conclusion in his doctrine on causality. As a result, it proves how Hume's argument on causality follows the same path as his epistemology, with the two ideas complimenting each other so that it is rationally impossible to accept the epistemology and not accept his argument on causality. Hume starts by explaining definitions of causes and characteristics that make up the popular definition of cause.
Contiguity is the idea that things go together, or are results of each other. Whatever objects operate together as causes and effects are seen as contiguous. There are chains of causes that lead to every effect, whether or not they can be discovered they are presumed to exist. As Hume puts it, "Heat and light are collateral effects of fire, and the one effect may justly be inferred from the other" (160). Along with contiguity is the concept of succession. The cause must precede the effect.
An object can be contiguous and occur prior to another without being its cause, a necessary connection between the two must be established. The relation of cause to effect does not depend on the known qualities of objects, but instead on the ideas of contiguity and succession, which are imperfect. Hume refutes the definition of cause as something productive of another, because cause and production are synonymous, and therefore one definition using the other is circular. Hume questions why it is necessary that everything whose existence has a beginning, should also have a cause. He also question 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. Contiguity and succession are not sufficient to make us pronounce any two objects to be cause and effect, unless we perceive, that these two relations are preserved in several circumstances. Instances of which we have had no experience, must resemble those, of which we have had experience. "Nothing so like as eggs; yet no one, on account of this appearing similarity, expects the same taste and relish in all of them.
It is only after a long course of uniform experiments in any kind, that we attain a firm reliance and security with regard toa particular event" (162). There is a transition from impression to idea, with the necessary connection possibly depending on the inference, instead of the inference depending on the necessary connection. The only connection or relation of objects, which can lead us beyond the immediate impressions of our memory and senses, is that of cause and effect, because we can base one inference from an object to another. The idea of cause and effect comes from past experience that informs us that some particular objects are conjoined with each other. There is, however, debate over whether a necessary connection exists between cause and effect. If cause and effect are connected, there must be a reason, or necessity for their connection.
All of our ideas are formed from impressions, therefore there must be an impression that forms the idea of necessity, if there really is such an idea. The idea of necessity lies between cause and effect, therefore that is where the focus must turn. When two objects are presented before us, one cause the other effect, no tie will ever be perceived uniting the two. All ideas are founded in impressions. The necessary connection between causes and effects is the foundation of the inference from one to the other. Nevertheless, necessity only exists in the mind, not in physical material objects.
"All inferences from experience, therefore, are effects of custom, not of reasoning" (164). The idea of the connection arises from the repetition of their union. That repetition doesn't change anything in the objects, or make them relate to each other, it only affects the mind. "Without the influence of custom, we should be entirely ignorant of every matter of fact beyond what is immediately present to the memory and senses" (165). There are two ultimate definitions of causality that Hume finally reaches. He sees them as either an object precedent and contiguous to another, where all the objects resembling the former are placed in a like relation of priority and contiguity to those objects that resemble the latter.
The other definition can be seen as an object precedent and contiguous to another, and so united with it in the imagination, 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 other. Hume sees the second definition of cause as being more accurate. The precedent and contiguous object seems to cause the effect, but in reality cannot be used to reason a necessary connection between cause and effect. The ideas of cause and effect, though they may be real, can only be supported by experience. David Hume's argument in his epistemology on impressions and ideas mirrors his argument on causation. He looks at many of the same concepts, including contiguity, succession, and resemblance.
Many of his arguments on causation refer back to the epistemology, concerning the connection between impressions and ideas, as well as memory and the imagination. After comparing the two arguments there is only one rational end that you can come to, with the arguments being founded on the same premises and not contradicting each other, if you accept one, you must accept the other. Perceptions that enter the body with force form impressions, including sensations, passions and emotions. "In all reasonings from experience, there is a step taken by the mind which is not supported by any argument or process of the understanding, there is no danger that these reasonings, on which almost all knowledge depends, will ever be affected by such a discovery" (163-4).
Those impressions are formulated in the composition of ideas. Impressions and ideas can be broken down into simple and complex. Simple perceptions or ideas admit of no distinction or separation, where complex can be divided into parts. Ideas are solely formed from impressions, and cannot be separated from those impressions.
Ideas and impressions always correspond to each other. You can, however, have complex ideas of which you never had impressions that corresponded to them in the same order. Therefore, you can imagine all sorts of things that you have never seen, such as the "golden mountain" (158). "When we think of a golden mountain, we only join two consistent ideas, gold, and mountain, with which we were formerly acquainted" (158). Though there is a great resemblance between complex impressions and ideas, they are not always exactly the same. Simple impressions, on the other hand, always form simple ideas that resemble them.
The idea can differ in degree from the impression, but not in nature. If simple ideas and impressions resemble each other, and complex ideas are formed from simple ones, then simple and complex are exactly correspondent. Ideas are preceded by other more lively perceptions, from which they are derived, and which they represent. Simple impressions are prior to their correspondent ideas. There can be certain impressions, however, that can be preceded by ideas, as in the case of reflection. An impression can strike the senses, and a copy of it taken to the mind, which will remain even after the impression ceases.
It forms a lasting idea. The memory and imagination copy that impression and make it into an idea that can eventually give rise to other impressions and ideas, making for an exception that still does follow the rules of impressions and ideas. There are forces that cause ideas to be associated with each other. They arise from resemblance, contiguity in time and place, and cause and effect.
Hume's doctrine on causality follows many of the same ideas through the process of his epistemology, as does his definition of causality in his section on knowledge and probability. The first of the similarities lies with contiguity. Impressions and ideas are related, just as cause and effect are thought of as being related. There is also a perceived succession in both cases. Impressions precede ideas, just as a cause precedes effect.
Even in the case of reflection, where a pre-conceived idea of the mind is there and can form other impressions, the initial impression comes before the idea. The concept of the impressions of the mind is one of the key pieces that associates Hume's epistemology and his argument on causation. Cause and effect are complex and distinct ideas of the mind that are spawned from impressions. Ideas are separable, therefore cause and effect are not necessarily associated. The ideas of cause and effect are contingent upon Hume's concept of impressions from his epistemology. Those impressions were formed from perceptions of relations between cause and effect, which are based on experience.
Impressions, in essence, formed the idea of a necessary connection between cause and effect. Impressions are based on experience, and the impression that formed the idea of a necessary relation between cause and effect was no different. The only reason for the idea of cause and effect being related was a previous experience, or custom that tied cause and effect together. Hume's doctrine on causality is firmly founded in the concepts from his epistemology.
His theories on the relation between impressions and ideas tie in directly with his idea of a necessary connection between cause and effect. We have internal impressions that form the ideas of necessity, and those ideas are based on repetition and resemblance, but do not prove the claim that there is a necessary connection between cause and effect. Ideas are not original, they are formed from impressions and influenced by resemblance, and experience. Cause is not an original idea, it is formed from impressions, which are in turn formed from experience. Therefore, we accept the idea of cause not because it is rational or well reasoned, but because of custom. Hume's position is consistent, and ultimately if you accept his epistemology, you must accept the reasoning behind his ideas on cause and effect..