This is the position that the human mind is not designed to find truth, and thus people should never pretend that they have a grasp of actual facts. Hume supported this idea with what is known as the problem of induction. He posited that the only way by which people could find (apparent) truth about things beyond the present testimony of the senses, and the records of our memory, was by inductive reasoning: extrapolating facts about the unobserved from facts of the observed (Hume, cited in Ariew & Watkins, 500). Thus we can know that the sun will rise tomorrow because it has risen today, and because it rose the day before, and so forth.
According to Hume, however, this extrapolation is an error of human judgment, for there is no logical reason to suppose that nature will continue to conform to our expectations; we obviously cannot prove such a fact by demonstrative reasoning, nor can we do so with inductive reasoning, which is precisely the thing we are trying to prove. Humes solution to the overwhelming skepticism that this idea entails is that we are gifted with instinct, an inherent understanding of the workings of the world. Or, as he puts it in his treatise An Enquiry into Human Understanding:
Nature, by an absolute and uncontrollable necessity has determined us to judge as well as to breathe and feel¦ (Elkin & Hume, 124) For Hume, this judging is predicated primarily on the observance of what he calls contiguous events, or events that happen with great propinquity. If a person views two events frequently happening in propinquity, then that person will begin to infer a causal relationship between the two events. So for example, if they see someone strike a bell, and then immediately hear a clang, they will link the two sensations together, and begin to believe that the one causes the other.
This belief becomes stronger the more times the striking of the bell and the clanging sound appear in conjunction to the observer, and such inference of cause and effect is, according to Hume, the basis of all beliefs. Since people believed that striking a bell causes a clang long before the establishment of the science of acoustics, our primary way of making sense of the world is through the perception of contiguous events, and the habit of inferring causation between them.
It is important to note that Hume never accepted that causality was necessarily a real phenomenon, but only that people and animals believed it was: when one particular species of event has always, in all instances, been conjoined with another, we make no longer any scruple of foretelling one upon the appearance of the other¦ We then call that one object, Cause; the other, Effect. We suppose that there is some connection between them; some power in the one, by which it infallibly produces the other, and operates with the greatest certainty and strongest necessity.
(Hume, cited in Ariew & Watkins, 520) Thus, Hume warned that there was a gulf between belief and truth, one that could not be bridged by human reason. We could be sure that striking a bell causes a clang no more than we could be sure that a crowing cock causes the sun to rise. According to Hume, we could be sure that one event causes another only if we were able to reduce the events to their elementary actions, and observe, at a fundamental level, their interaction.
Since the mind perceives only actions at the compound level, we can never be sure that events are tied by causality, no matter how many times they appear in conjunction. If we could be sure of such things, argues Hume, then we would be able to determine the effects of causes without having to resort to actual demonstration or induction. Likewise, no event would appear to us as a chance occurrence, since we would be aware of all of the unobservable elementary interactions that make up the concept of chance. Take, for example, a dice throw. If someone were to roll a six, it would ostensibly appear to be a lucky throw.
However, if one were aware of every factor that influenced the throw, from the way up the dice was facing before the throw to the precise movement of the hand as it shook the dice, then the dice roll could always be predicted with perfect accuracy, and it would therefore cease to appear as an adventitious event. For Hume, a determinist, these principles that operate inanimate objects can be applied to the workings of the human mind. Since we cannot be sure that striking a bell causes a clang, neither can we be sure that willing ones arm to be outstretched causes the arm to be outstretched.
In fact, Hume argues, we can be even less sure of the causal link between willing and doing than we can about the mechanics of inanimate objects, since the mind operates on a far more complex level about which we know far less. This brings Hume, and us, to the free will debate. If the causal link between volition and action is illusory, how can anything we do be under our control; how can we have free will? Unlike many determinists, Hume believes that his naturalism is reconcilable with the idea of a free will, a philosophical position known as compatibilism.
In section VIII, part one of his treatise, An Enquiry Into Human Understanding, Hume states that the biggest obstacle to agreement amongst disputants on the free will debate is the lack of precision and universality of the terms used by the disputants: From this circumstance alone, that a controversy has been long kept on foot, and remains still undecided, we may presume that there is some ambiguity in the expression, and that the disputants affix different ideas to the terms employed in the controversy. (ibid, 522) And thus he goes on to provide discrete definitions.
The first term he employs is necessity, and by this he means the apparent need of one event to trigger another: The uniformity, observable in the operations of nature; where similar objects are constantly conjoined together¦ (ibid, 523) So, for example, striking a bell is a necessity of a bell clanging. The next term Hume defines is liberty, and he uses this to refer to a specific type of free will: A power of acting or not acting, according to the determinations of the will¦ (ibid, 484) With this foundation, Hume goes on to attempt to reconcile his views.
According to Hume, since a dice roll cannot easily be predicted, even though it runs according to fixed (albeit unobservable) laws, the same could be said of human behavior: I assert the necessity of human actions, and place them on the same footing with the operations of senseless matter. (Hume & Mossner, 457) Thus, if a person acts contrary to an observers expectations, then it is only because the observer is unaware of the necessities that cause the strange behavior; if the observer were aware of such necessities, then they would be able to predict the persons behavior as easily as that of an inanimate object under simple force.
Where a dice roll would be unpredictable to someone unaware of the way up the dice was before it was rolled, so a persons behavior would be unpredictable to someone unaware of the motivating forces behind their actions. Thus, any causality that an observer may ascribe to a persons actions is mere conjecture, and doesnt reflect the actual necessity of said actions. This does not mean, however, that human behavior is not subject to necessity. For if it werent, then: Actions would have so little in connection with motives, inclinations and circumstances, that one does not follow with a certain degree of uniformity from the other.
(Hume, cited in Ariew & Watkins, 528) And so it would be impossible to have any idea at all what a person was going to do next; human behavior would be a matter of pure chance, which is incompatible with the idea of a deterministic universe. Thus, because chance is not the cause of human action as directed by the will, then something else has to be, and for Hume, that something is liberty. Hume argues that not only does necessity allow liberty, but liberty requires necessity, for someone couldnt outstretch their arm by willing it if there were no necessity.
Furthermore, Hume argues, in order to be held morally accountable for ones actions, one must have both liberty and necessity, as without either, one cannot be in control of what one does: Actions are, by their very nature, temporary and perishing; and where they proceed not from some cause in the character and disposition of the person who performed them, they can neither redound to his honor, if good; nor infamy, if evil. (ibid, 530) Because of this line of reasoning, Hume could be accused of making the mistake of trying to bolster the verity of his idea by appealing to human sentiment, which obviously has no correlation to truth.
Just because it benefits society to hold people morally accountable for their actions, it doesnt mean that people actually are accountable. This is not the only criticism that could be leveled at Humes philosophy. He could also be accused of not playing fair by redefining the terms of liberty and necessity to suit his own purposes. He may have managed to reconcile his own terms, but the same cannot be said of the commonly held views of free will and determinism, where a gulf of incompatibility still exists to this day.
In addition, Humes philosophy makes undue assumptions about the nature of people; namely that people can be compared to inanimate objects, and that mental constructs like motive and reason are universally consistent from person to person. If Humes work were first published today, where people tend to hold a far more relativistic view of thought and action, and understand the importance of the unconscious mind in dictating the two, it would no doubt strike discord in many readers.
But such criticisms are relatively trivial, and inevitable, given that Humes work was written over two centuries ago, when knowledge was scarcer than it is today. Though far from perfect, Humes novel approach to the rationalization of human nature was amongst the most seminal of philosophical treatises, helping to pave the way for empiricism and the very fact that this essay has been written, and is being read, lays testament to the extent to which Humes thinking pervades the modern age.
Citations: Ariew, R. & Watkins, E. Philosophy: An Anthology of Primary Sources. Hackett Publishing, 1998. Elkin, W. B. & Hume, D. Hume: The Relation of the Treatise of Human Nature, Book 1, to the Inquiry Concerning Human Understanding. Cornell University Press, 1904. Hume, D. & Mossner E. C. (Ed). A Treatise of Human Nature. Penguin Classics, 198