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An examination of David Hume’s Theory of Non-Sensory Sources

I shall argue that Hume does not account for non-sensory sources in his claims regarding efficient causes. Not all claims of possible perceptions of things in the world must be derived from an impression. It is not a necessary requirement of a thing to be perceived by sensation or reflection for it to have the force of efficacy. G-d does not exist as a cause solely because there are effects resulting from his existence.

Hume fails to account for non-sensory sources in his claims regarding efficient causes. There are things that might exist in the world that cannot be sensed. Things that have not yet been discovered could still exist. Our sensing, or rather our ability to sense something, does not bring about the existence of that thing. Conversely, our inability to sense something does not prevent that thing from existing. “Jacques Monod, the French Nobel Prize-winner advances the possibility that all living matter on this planet derives from one single nucleic acidic molecule” (Munck, 1974:31).

Before we could sense the effects of a certain disease, the disease did not necessarily fail to exist. Rather it lay dormant, either in other creatures or within a person. To say that a planet that has not yet been seen by the human eye does not exist is not a logical claim. It would not be a logical claim to say that until the planet is observed it might not be sensed. Nobody has seen the planet, because it potentially has not yet been discovered. Our inability, however, to depict an idea / image of something that has not yet been perceived by our senses, is totally independent of the actual reality of that thing.

A father cannot sense the pain involved in the labor process for giving birth to a baby. While he can, however, empathize with the mother who is birthing. He can hold her hand during labor to gain a sense of the degree of pain that she might be experiencing as a result of birth pangs. The husband could not actually know the intensity of the discomfort his wife may be feeling. He may have an idea of pain from his own experiences and could imagine the magnification of uneasiness. This seemingly relative process of empathizing does not really provide him with a real understanding of these aches, which he had never directly experienced. The same argument could be applied to one’s ability to sense a deity, using parallel reasoning, as will be demonstrated throughout this discourse.

A disease, which could be could damaging to one’s health and manifests as rashes all over oneself, with symptoms of vomiting and discomfort, is phenomenon of which one could have some awareness. One does not, however, sense the disease itself, but only its effects as the disease interacts with one’s immune system, which strives to purge out. The cause of the disease is one that one might not be able to observe through reflection or sensation. Nevertheless, the results and the effects of the illness are apparent to oneself. One is immediately aware of the pain that one feels and the fear of the progression of the sickness, while one still remains physical distinct from actual disease.  There must be a cause that is linked to the horrible effects of the disease. One is not in any way to determine the cause intrinsically. One can rely on the advice of medical experts as to possible causes. Yet one will never know with certainty what actually caused the sickness to manifest within one’s physical being.

In the example of the woman giving birth, it would be beneficial to search for the process by which she became pregnant. Obviously there was a process of conception that led to her giving birth. Will the baby have any conscious awareness of having been conceived, which was the initial cause of its birth. Is it possible that the baby could have a perception of its being created? Perhaps there is a way for the memory to be realized through some psychological regression exercise. The same line of reasoning could be applied to our comprehension of G-d and our ability to perceive of the existence of the Divine.

At some point in time there must have been a perception of G-d. How could we have an idea of the Divine, unless there was an impression of the Divine at some time in History? The idea of G-d does exist in the minds of the majority of world’s population. But what is this idea of which people have a mental perception? There is not a universally accepted image of G-d’s from or appearance – if there is one that a human being could possibly conceive of – but there is an agreement by many religious factions that such an entity does in fact exist. According to the Hebrew Bible, at the revelation of G-d, at Mount Sinai, was observed by millions of people witnessed (six hundred thousand men). The discussion must now focus on what it truly means to witness G-d. Did these observers really see any type of form?

It is written in the Hebrew Bible, that when the Hebrews witnessed G-d, they became spiritually elevated and were unable to perceive in a physical sense. Following this experience, the Hebrews reached the land of Israel and have faithfully continued to believe in the existence of the Divine. While there was never a real observation of an actual image of the Divine, there were created many believers whose descendants are now today also believers. The proof that G-d exists is not in the form or in the way of an image, but in the result or effect of the realness of the Divine. Within the Bible there are laws that are followed by a segment of society, some of which are opposed by others. This document contains clearly delineated punishments for those who disobey or transgress the prescribed laws. If someone asked a person who was being punished for breaking a law, why they believed they were being punished, they might claim that their predicament has something to do with disobedience to the Divine command, even if they were not a so-called believer.

The person being punished would likely agree that. “it is morally necessary to assume the existence of G-d” (Kant, 1948:22). An impression of a thing, however, does not guarantee its actual existence. Hume would disagree with Kant on this claim. He would argue that: “necessity is something that exists in the mind, not in objects: nor is it possible for us ever to form the most distant idea of it…” (Hume, 1985:166). There was necessity for laws to be established, in order to secure the lives of the Hebrews in the desert. Therefore, it was necessary to conceive of a deity, who would be the very source (cause) of the forced compliance with the laws (effects).

There are things in the world that might exist, but we are not able to observe them in a tangible form. We have an innate idea of them, but cannot physically demonstrate them. Among these things are commensurable lines, perfect triangles and the middle shade of blue that has yet to be colored. In the example of the perfect triangle, Kant explains:

the proposition that a triangle has three angles is absolutely necessary; and thus they spoke even of an object that lies entirely outside the sphere of our understanding…The…proposition does not say that three angles are necessary absolutely…under the condition that a triangle is there three angles necessarily are also there (in it)”, (Kant, 1996:579).

Kant then argues that, “people framed prior concept of a thing and arranged this concept in such a way that, in their opinion, it comprised in its range also” (Kant, 1996:580).

In addition, existence of numbers can be questioned. For example, the written number four can clearly be seen in written form on paper before my eyes (if I wrote it out). I only have a vague idea of what the actual number four is and this idea is an innate one. This idea can be explained through the use of mathematical models, but the source of our cognitive awareness of numbers is unknown. Likewise, in the case of a deity, Hume has not clarified its source.

We have images of various things in our mind, even though we have not yet observed them. There might exist somewhere a perfect triangle, but until one can be displayed, its existence remains in dispute. The same claim can be used to represent the intuitive knowledge of G-d. One could read the Bible and gain an understanding of the results of G-d’s existence, within those pages that one reads. From there, an image of what G-d might be can be formed. Kant believes that we have an idea of a deity that does not come from an impression, but rather from another source. The idea of G-d is derived from pure reason. Kant claims: “the concept of a supreme being is in many respects a useful idea. But this idea…is quite incapable of allowing us to expand…our cognition regarding what exists” (Kant, 1996; 585). He further claims that: “all real properties in a thing is a synthesis whose possibility we cannot judge a priori…the possibility of synthetic cognitions must always be sought only in experience; the object of any idea, however, cannot belong to experience” (Kant, 1996; 585-586).

Hume wrote a contrary claim. He argues that: “the supposition of a deity can serves us in no stead, in accounting for that idea of agency, which we search for in van in all the objects, which are presented to our senses, or which we are internally conscious of in our own minds” (Hume, 1985; 160). Hume continues to require an impression of a thing to prove its existence. This impression of a thing, for Hume, must be either a sensation or a reflection. But Hume does not account for innate ideas, in the respect that one can have an image of something that one has not sensed or reflected, as is demonstrated in the case of the missing shade of blue. He leaves himself vulnerable for critique when he states: “the conception always precedes the understanding” (Hume, 1985; 164). If the conception does precede the understanding, the Hume could conceive of a deity without having understood it. The failure to comprehend something does not prevent the conception of the thing itself.

Hume fails to defend his claim against the possibility of the existence of a deity, when he claims: “we can never have reason to believe that any object exists, of which we cannot form an idea” (Hume, 1985; 172). If this claim is further employed in an argument against that which is not necessarily an object, but a being in existence, then Hume cannot argue against the existence of a deity, in which an idea can be formed, regarding its existence. The examination of Hume’s general rules of causes and effects might help to clarify his position. Hume claims that: “the same cause always produces the same effect, and the same effect never arises but from this same cause” (Hume, 1985; 173). This claim is not a valid claim and can be disproved of being an absolute claim. If a match is struck against a surface and is ignited a set number of times, it is not certain that each time, the striking of the match (the cause) will produce the ignition of the flame (effect), (Johnson, 200).

If Hume erred in judgment regarding his own set of general rules for objects and their causes and effects, he could have erred elsewhere in his claims. Hume does not account for non-sensory sources in his claims regarding non-sensory sources. There are things in the world that do exist, both in observable form and in the mind, which cannot be sensed. It is possible that these things have not yet been discovered (as in the case of the missing middle shade of blue or things that are not sensible, such as the number four). Not all claims of possible perceptions of things in the world must be derived from an impression. Just because a perfect triangle cannot be drawn, does not imply that it could not actually exist. It is not a necessary characteristic of a thing to be perceived by sensation or reflection, in order of it to have the force of efficacy. In summation, G-d does exist as a cause, because there are observable effects as a result of the existence of the Divine.


Ed. L.A. Selby-Bigge. Hume, David. A Treatise of Human Nature. 2nd Edition. Section XIV, Oxford: Oxford University Press, 1985.

Munk, Eckehard. Biology of The Future. Great Britain: Jarrold & Sons Ltd, Norwich, Collins Publishers: International Library, 1974.

Translated by Werner S. Pluhar. Kant, Immanuel. Critique of Pure Reason. Unified Edition. Indiana: Hackett Publishing Company, Inc., 1996.

Translated by T.K. Abbott. Kant’s Critique of Practical Reason. London: Longmans Green and Co., 1948.


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