Hume and the Lack of a Causal Link Between Our Known Experiences and the Existence of a Supreme Being
The "here and now": That is what concerns David Hume. There is simply no value in discussing such amorphous intangibles as one can infer from "the course of nature." More precisely, humans -- of them, philosophers -- cannot and should not be enticed to "regulate" their "conduct" by parameters such as the afterlife or God. Hume grounds his thinking in causality -- specifically the lack of causal link between "the experienced train of events" and the existence of a perfect being.
To understand Hume's view that contemplations of God are "uncertain and useless," one has to begin with Hume's philosophical methods. Hume is an empiricist philosopher. Hume works to bring the rigors of scientific methodology to the otherwise more fluid process of philosophical reasoning. The critical lynchpin here is Hume's distinction between matters of fact and relations of ideas.
Hume explains that anything one can say about the world is a matter of fact -- as in, experiences. However, these matters of fact can be denied without contradiction, as someone else's experiences are entirely different. Relations of ideas can teach us about mathematical or scientific truths and principles but cannot teach us about ourselves, the existence of an external world or afterlife, or God. Hume's belief here differs starkly from rationalist philosophers'.
That is why Hume distrusts arguments for God's existence based on causality. Hume writes, "The great source of our mistake in this subject, and of the unbounded license of conjecture, which we indulge, is, that we tacitly consider ourselves, as in the place of the Supreme Being, and conclude that he will, on every occasion, observe the same conduct, which we ourselves, in his situation, would have embraced as reasonable and eligible." (100)
This is not so at all, according to Hume. We only know facts and experiences; we cannot extrapolate from them to predict future experiences or happenings. To use his example, just because an observer sees a half-finished building with bricks and mortar around it, one cannot assume that the building will be finished, let alone in a particular "reasonable and eligible" manner.
Hume believes that two facts that seem to be linked do not at all allow us to assume causality. They simply could be coincidentally linked; in fact, they are so. God's existence, according to Hume, simply cannot be proven by using causality. As far as God's existence is concerned, "It is uncertain; because the subject lies entirely beyond the reach of human experience. It is useless, because our knowledge of this cause being derived entirely from the course of nature, we can never, according to the rules of just reasoning, return back from the cause with any new inference, or making additions to the common and experienced course of nature, establish any new principles of conduct and beaviour." (100)
Hume is essentially a hard-liner on inability to prove God by causation. By simple virtue of the fact that anyone who has experienced the afterlife or the present presence of God (Supreme Being) cannot communicate with those in this life. So, it is not rational to set behavior and rules and "experiences" based on theories of the afterlife, regardless of causality.
Here, Hume uses the word "return." One cannot return from the afterlife or an experience with God to the everyday life to communicate his findings. Therefore, even though it is quite rational to assume that the building Hume refers to will get built if bricks and mortar surround it, one cannot infer the presence of God.
Truly, Hume's thinking here relates back to his views on causality in general. Hume claims that we know causality only through experience. Hume writes, "All events seem entirely loose and separate; but we never can observe any tie between them. They seem conjoined, but never connected." (49) For Hume, to infer without circularity that future "experiences" will resemble past experience requires some additional linking step that cannot be grounded in past experience.
For Hume, there is a logical bridge that is missing in causality. All we know is what we have experienced. We simply cannot extrapolate from there to predict future experiences, because that requires a step that isn't experience; and since all we know is experience, that step is not allowed. A circular argument indeed, but a highly rational one.
But Hume is a pragmatist too. He acknowledges that we make daily decisions based on past experiences and make those decisions via supposed or assumed causal links. He admits that life as we know it would cease to exist if we did not do these things. For instance, on past days with heavy thunder clouds, rain has almost always fallen. Naturally we will take umbrellas with us to work the next time we see thunderheads.
Where Hume distinguishes his lack of faith in causality is by explaining that we can go ahead and make these inferences -- we are just not rationally justified in doing so. There simply are no grounds for certainty or proof of these causal links.
We truly never know the underlying connection between cause and effect, according to Hume. He writes, "It appears that, in single instances of the operation of bodies, we never can, by our utmost scrutiny, discover any thing but one event following another; without being able to comprehend any force or power, by which the cause operates, or any connection between it and its supposed effect." (49)
Hume replaces the link between cause and effect with his belief that nature leads us to believe the things that we do. Essentially, Hume's belief is that routine, past success in prediction and habit leads us to make future predictions, and since they are often correct, we do not worry about believing certain things very much. Certain events are grouped together by our observation of nature, and cause and effect have nothing to do with our beliefs.
On God and the afterlife, Hume writes that we cannot prove either's existence to our senses, but it seems like a relatively safe assumption to make. In fact, it is an assumption that makes leading our lives easier. That is where the cynicism in Hume truly shows. We believe in God and the afterlife not because of some causal link, but because of convenience. Hume uses the example of the man who is struck by palsy who first tries to move the unmovable body parts as he used to. " ... Consciousness never deceives ... We learn the influence of our will from experience alone. And experience only teaches us, how one event constantly follows another; without instructing us in the secret connexion, which binds them together, and renders them inseparable." (43)
Experience does not teach us of the connection simply because there exists none. Our experience alone dictates that certain events happen in succession; we cannot assume causality. For Hume, nature always wins out against abstract reasoning. There is no good or solid reason for us to reason by cause-and-effect, yet we continue to do so because it is convenient.
Our inductive reasoning "skills" result from custom and not understanding of cause and effect. Hume illustrates this by pointing out that someone thrust into the world with no background would have no understanding of cause and effect. Life would just be an endless stream of disparate and unlinkable events. We do not intuit "cause and effect." Rather, we see a process happen many times in a row, and then we are able to make predictions, and we assign them to cause and effect, when in reality the true process is simple custom or habit. Or, alternatively, observations of nature.
Observations of physics are critical to Hume's argument: We may observe phenomenon such as objects in motion tending to stay in motion, or light refraction, but we need to observe them many times in order to intuit any "cause and effect." But, really we are doing nothing of the sort. We are simply observing habit and custom.
With God and the afterlife, we have simply noticed that many things have no explanation, and therefore, via cause and effect, assign those things to a presence of God. In reality, these are observations of custom, nature and habit. We cannot prove God; several events in a row though convince us that He must exist; This is not cause-and-effect for Hume at all.
With the afterlife, convenience plays more of a role for Hume. It is simply more convenient, or reassuring, to believe that life exists after this Earth. Nature, habit and custom are not as involved here. We simply do not want to believe that life as we know it ends; rather, we want it to move forward. There is even less evidence of cause and effect here for Hume, since we cannot even string events together that will point in the direction of an afterlife.
That is why Hume first believes that God is "uncertain." We…