Hume’s writings were rather notorious for the ways that they suggested (or at times explicitly argued for) conclusions that were either in tension with or outright contrary to the Christian religious worldview. In several cases Hume’s arguments were only published posthumously, for fear of persecution for being an atheist, or at least an “unbeliever”. In large part they further evince Hume’s commitment to a kind of skeptical empiricism, as well as to a conception of reason as nothing more than instrumentally useful. We can have no rational insight into reality or the nature of things.
In Hume’s day proofs of the existence and nature of God typically fell into two groups—natural and revealed theology. In these notes I discuss elements of Hume’s critique of natural theology from his Dialogues Concerning Natural Religion and his critique of revealed theology from his essay “Of Miracles”, which is one of his earliest works but was only finally published in 1748 as chapter ten of the Enquiry Concerning Human Understanding.
Hume’s Critique of Natural Theology
In the Dialogues Hume, primarily through the character Philo, mounts a series of arguments against the conclusions of natural theology. Natural theology concerns itself with what we can know about the existence and nature of God based on evidence from nature. One of Hume’s main targets in the Dialogues is the position in natural theology that we can know there is a perfectly good, powerful and omniscient God who is concerned with our human lives by virtue of inferences based on the orderly design of nature. This argument, often called the “design argument” (or “argument from design”) was extremely popular, often considered to provide the intelligent and educated with a firmly rational basis for belief in the existence of the Christian God.
We see a version of the design aragument advanced in the fifth paragraph of Part II, where Cleanthes likens nature to a kind of massive and extremely complex machine, whose parts are all orderly and systematically related to one another.
Look round the world: Contemplate the whole and every part of it: You will find it to be nothing but one great machine, subdivided into an infinite number of lesser machines, which again admit of subdivisions, to a degree beyond what human senses and faculties can trace and explain. All these various machines, and even their most minute parts, are adjusted to each other with an accuracy, which ravishes into admiration all men, who have ever contemplated them. The curious adapting of means to ends, throughout all nature, resembles exactly, though it much exceeds, the productions of human contrivance; of human design, thought, wisdom, and intelligence. Since therefore the effects resemble each other, we are led to infer, by all the rules of analogy, that the causes also resemble; and that the author of nature is somewhat similar to the mind of man; though possessed of much larger faculties, proportioned to the grandeur of the work, which he has executed. (§2.5; p. 15)
So just as the order and complexity of a human artifact, such as a clock, can only be understood by means of appeal to a human designer, so too the universe can only be understood as the product of an infinitely more powerful designer – God. The argument thus provides a kind of empirical certainty (i.e. a form of certainty based on our experience of the world) for God’s existence and nature.
Hume advances three objections to this argument, all of which derive in one way or another from his conception of causal reasoning as advanced in his other works (i.e. in the Treatise and the Enquiry).
The first objection is that the design argument makes a kind of inference from analogy, which is unreliable the further we get from the exact circumstances of the machine-designer scenario.
The exact similarity of the cases gives us a perfect assurance of a similar event; and a stronger evidence is never desired nor sought after. But wherever you depart, in the least, from the similarity of the cases, you diminish proportionably the evidence; and may at last bring it to a very weak analogy, which is confessedly liable to error and uncertainty. (§2.7; p. 16)
Hume’s thought here is that the further one deviates from the original case the weaker the analogy gets.
The analogical reasoning is much weaker, when we infer the circulation of the sap in vegetables from our experience, that the blood circulates in animals; and those, who hastily followed that imperfect analogy, are found, by more accurate experiments, to have been mistaken. (§2.7; p. 16)
Hume’s second objection is that we can’t claim, independent of experience, what forms of matter can or can’t arrange themselves into ordered systems.
matter may contain the source or spring of order originally, within itself, as well as mind does; and there is no more difficulty in conceiving, that the several elements, from an internal unknown cause, may fall into the most exquisite arrangement, than to conceive that their ideas, in the great, universal mind, from alike internal, unknown cause, fall into that arrangement (§2.14; pp. 17-18)
Is nature in one situation, a certain rule for nature in another situation, vastly different from the former? (§2.23; p. 20)
The point here being that we cannot say for certain that ordered effects of nature cannot be produced from mindless (or at least non-intelligent) causes as well as from intelligent ones. Hence we cannot easily deduce from an ordered design that some intelligent designer was at work.
Hume’s third objection is that
When two species of objects have always been observed to be conjoined together, I can infer, by custom, the existence of one wherever I see the existence of the other: And this I call an argument from experience. But how this argument can have place, where the objects, as in the present case, are single, individual, without parallel, or speciﬁc resemblance, may be difficult to explain. And will any man tell me with a serious countenance, that an orderly universe must arise from some thought and art, like the human; because we have experience of it? To ascertain this reasoning, it were requisite, that we had experience of the origin of worlds; and it is not sufficient surely, that we have seen ships and cities arise from human art and contrivance (§2.24; pp. 20-1)
Hume’s point here is that the kinds of causal inferences that we can be confident of are those based on the constant conjunction of exactly similar types of events or objects. But to be similarly certain that the ordered effects nature are the result of an intelligent cause we would have to be in a position to observe the constant conjunction of intelligent causes and the generation of universes, which we are clearly unable to do.
Hume’s Critique of Cosmological Arguments
The design argument is an argument based on experience, or an “a posteriori” argument. In the Dialogues Hume has Demea admit that such a line of argument is a failure, and instead propose an argument that is independent of experience, or an “a priori” argument, for God’s existence. The version of the cosmological argument that Demea offers here is as follows:
Whatever exists must have a cause or reason of its existence; it being absolutely impossible for anything to produce itself, or be the cause of its own existence. In mounting up, therefore, from effects to causes, we must either go on in tracing an infinite succession, without any ultimate cause at all, or must at last have recourse to some ultimate cause, that is necessarily existent: Now that the first supposition is absurd may be thus proved. In the infinite chain or succession of causes and effects, each single effect is determined to exist by the power and efficacy of that cause, which immediately preceded; but the whole eternal chain or succession, taken together, is not determined or caused by anything: And yet it is evident that it requires a cause or reason, as much as any particular object, which begins to exist in time. The question is still reasonable, why this particular succession of causes existed from eternity, and not any other succession, or no succession at all. If there be no necessarily existent being, any supposition, which can be formed, is equally possible; nor is there any more absurdity in nothing’s having existed from eternity, than there is in that succession of causes, which constitutes the universe. What was it then, which determined something to exist rather than nothing, and bestowed being on a particular possibility, exclusive of the rest? External causes, there are supposed to be none. Chance is a word without a meaning. Was it nothing? But that can never produce anything. We must, therefore, have recourse to a necessarily existent being, who carries the reason of his existence in himself; and who cannot be supposed not to exist without an express contradiction. There is consequently such a being, that is, there is a deity. (§9.3; p. 54-5)
Hume (via Cleanthes) offers five objections to this argument. His first objection, which Cleanthes claims is “entirely decisive”, is a general statement denying that claims about what exists can be proven by a priori demonstration (§9.5).
there is an evident absurdity in pretending to demonstrate a matter of fact, or to prove it by any arguments a priori. Nothing is demonstrable, unless the contrary implies a contradiction. Nothing, that is distinctly conceivable, implies a contradiction. Whatever we conceive as existent, we can also conceive as non-existent. There is no being, therefore, whose non-existence implies a contradiction. Consequently there is no being, whose existence is demonstrable. I propose this argument as entirely decisive, and am willing to rest the whole controversy upon it. (§9.5; p. 55).
The argument advanced here is based on Hume’s view that anything that is conceivable (imaginable) is thereby possible, and that what is necessary must be such that its rejection or negation is (or implies) a contradiction. According to Cleanthes, the rejection of God’s (necessary) existence as ultimate cause is neither itself a contradiction, nor does it imply one. Therefore we cannot demonstrate through an a priori argument the existence of a necessary being.
Hume here assumes (though does not really explain) a conception of causation he has argued for in his other work. At its base is the idea that there is no (or no knowable) necessary connection between any distinct existences. Hence there is no contradiction in assuming the possibility of an effect without its normal cause, or indeed any cause at all. Moreover, since Hume construes a “contradiction” (and thus impossibility) as entirely psychological, i.e. as the incompatibility of two ideas, he construes possibility as determined by what we can conceive or imagine. In this case, he thinks we can simply imagine an effect – the universe at its beginning – without any further cause.
Cleanthes’ next two objections concern the concept of necessary being. He claims, first, that the concept has no consistent meaning, and then suggests that, by one account of its meaning, the material universe may be this necessary being (§9.6-7). This possibility is significant because it undermines the idea, central to Demea’s theological argument, that the necessary being is an intelligence. Cleanthes’ final two criticisms challenge Demea’s assumption that an eternal series of contingent events must have a cause (§9.8-9), and work along the lines set by the initial argument about causation.
Hume’s Critique of Revealed Theology
“Of Miracles” concerns revealed theology, which presumes God’s existence and/or nature to be revealed truths rather than ones knowledge of which is deduced through evidence or argument. Hume’s main aim in this essay is to undermine our confidence in the verdicts of revealed theology and thus provide “an everlasting check to all kinds of superstitious delusion” (E I.2; p. 108).
Hume argues that all “matters of fact”—i.e. matters concerning local, contingent, or empirical truths (as opposed to mathematical or logical truths, which are non-empirical and necessary)—are known through experience and our confidence in the truth of some claim should not exceed the empirical evidence for it. As Hume puts it, a “wise man, therefore, proportions his belief to the evidence” (E I.4; p. 108). Of special note here is that Hume considers the relation of support between evidence and judgment to be that of probability. Evidence for X means that our confidence in the probability of X’s being the case should increase.
when at last he fixes his judgment, the evidence exceeds not what we properly call probability. All probability, then, supposes an opposition of experiments and observations, where the one side is found to overbalance the other, and to produce a degree of evidence, proportioned to the superiority. (E I.4; p. 108)
Part I of the essay then concerns itself with two sources of evidence: experience and testimony. Hume contends that testimony, which is itself based on a person’s experience, cannot provide evidence greater than experience itself, and is itself only treated as reliable because past experience has shown that (credible and honest) people’s testimony generally reflects the facts. This then generates a conflict when the testimony concerns some unusual event:
The reason why we place any credit in witnesses and historians, is not derived from any connexion, which we perceive a priori [i.e. independent of experience], between testimony and reality, but because we are accustomed to find a conformity between them. But when the fact attested is such a one as has seldom fallen under our observation, here is a contest of two opposite experiences; of which the one destroys the other, as far as its force goes,and the superior can only operate on the mind by the force, which remains. The very same principle of experience, which gives us a certain degree of assurance in the testimony of witnesses, gives us also, in this case, another degree of assurance against the fact, which they endeavour to establish; from which contradiction there necessarily arises a counterpoise, and mutual destruction of belief and authority. (E I.8; p. 110)
Since experience is what provides evidence for the reliability of testimony, when someone testifies as to an unusual event (i.e. an event that is not typical in experience) they are undermining the basis for our belief in them. Since miracles are, by definition, extraordinary events not found in the typical course of experience, they present an especially problematic case for explaining why they deserve rational belief. As Hume then puts it,
no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavours to establish: And even in that case there is a mutual destruction of arguments, and the superior only gives us an assurance suitable to that degree of force, which remains, after deducting the inferior (E I.13; p. 112)
Having established this “maxim” concerning the belief of miracles through testimony, Hume goes on, in Part II, to argue that no testimony concerning any miracle (or more broadly, any extra-mundane religious fact) should be believed. Since the probability of the testimony’s being false is always greater than the probability that the ordinary course of nature has been altered, “no human testimony can have such force as to prove a miracle, and make it a just foundation for any such system of religion” (E II.35; p. 122).
More generally, Hume contends that there is no rational basis for belief in religion (and in particular the Christian church) in so far as it relies on testimony concerning miraculous happenings or on the word of prophets.
upon the whole, we may conclude, that the Christian religion not only was at first attended with miracles, but even at this day cannot be believed by any reasonable person without one. Mere reason is insufficient to convince us of its veracity: And whoever is moved by faith to assent to it, is conscious of a continued miracle in his own person, which subverts all the principles of his understanding, and gives him a determination to believe what is most contrary to custom and experience. (E II.41; p. 125).
The Christian religion seems to require belief in miracles on the basis of testimony, but if Hume’s argument is correct, religion can provide no rational basis, no reason, for doing so, and perhaps even more damning, we have many reasons to reject such claims as false (i.e. as less probable than their denial).