David Hume

Giant of Philosophy: David Hume (1711-1776)

By Leo Kee Chye

David Hume
Scotland (1711 – 1776)

Reading David Hume’s works is an enjoyment per se. Nothing could be more fun and exciting than to read our David Hume armed only with his pen brought down the Goliaths, the Goliaths of philosophy then. He, however, reputed to have the sharpest of intellect and yet was ignored, misunderstood and misrepresented during his lifetime. It was some thirty years after his death when another equally brilliant philosopher Immanuel Kant took Hume seriously or in Kant’s words, “…awoken me from my dogmatic slumber.” And it was from this awakening that the world gave Hume his overdue recognition and fame.

David Hume the man
Hume, a Scotsman who was born in Edinburgh in 1711, displayed a scholarly disposition since as a child. Although a lawyer was what his family hoped he would become, young Hume’s real passion was philosophy and literary pursuits. Before the age of 27, Hume published his first philosophical work A Treatise of Human Nature, but it “fell dead-born from the press.” And for many years, he did not achieve the literary fame he ardently sought for. Strangely, it was his four volumes of the History of England that bought him recognition in the literary world. Although he rewrote and published Human Nature, alas it was again poorly received but also aroused the hostility of lesser men.

The Goliaths of philosophy
Who were these Goliaths of philosophy then and what has our David done to incur their wrath? They were, for that matter, the Rationalists and Empiricists.

It was the Age of Enlightenment then. The European discovered, for the first time, in their possession–Reason, a tool that not only can peek into the workings of Nature but also to tame her which before they could only quietly accept with dogmatisms and resignation her doings. But the question was, among the Rationalists and Empiricists, how best should this tool be employed in order to obtain indubitable knowledge of the world.

Rationalists 
Led by Descartes, Spinoza and Leibniz, Rationalists believed only pure reason can give rise to true knowledge of the world. It was no coincident that the Rationalists at that time were themselves brilliant mathematicians. Citing Euclid’s Geometry as an example, whereby merely basing on a few self-evident axioms, Euclid was able to derive the whole system of geometry where its veracity is irrefutable. Rationalists sought to do to the world what Euclid had done for Geometry: with reason only. Sensory experiences, on the other hand, are unreliable source of knowledge. Take for instance a stick half way dipped into a glass of water, it may look bent but your mind will tell you not. However that is not to say Rationalists distrust sensory experiences but only to regard them as inferior when compared to pure reason. Interestingly, Rationalists using this approach concerned themselves not so much with the world of appearance but the reality beyond the world of appearance. That is, what makes the world is, the way it is, and the world is not, the way it is not. Descartes, for example, approached it in an ingenious way. By doubting everything that he has had previously took for granted, he arrived at something that is indubitable which was his famous “I think, I am.” And from this innocuous statement, Descartes erected the pillar from which the whole knowledge of the world is supported on. Leibniz, on the other hand, used a few self-evident axioms to derive the world as we see today. One interesting axiom he used was the principle of sufficient reason and in his own words “there can be found no fact that is true or existent, or any true proposition, without there being a sufficient reason for its being so and not otherwise, although we cannot know these reasons in most cases”. Put it simply; imagine dominoes, hundreds of them, stack up side by side. Topple one of them over; you will see the ” domino effect” of the fall of one led to the fall of the other and the other… In the same vein, it is this “domino effect” or sufficient reason that governs the world. All the events and things can be traced back to another set of events and things from which can be traced back further to another set and another set…ad infinitum. Since there must be a sufficient reason to the existence of this ad infinitum chain of things and events, it follows that it must lie outside this world of ours; and God is the only source of this sufficient reason; hence God exists.

The problems of a rationalist approach to knowledge are:

• Without references to experience, many of the theories propounded are purely speculative, difficult to ascertain their veracity.
• The so-called innate ideas of human, the rationalists claimed we have, are often tautological statements which say nothing of the real world in which we live in.
• Rationalists also have a hard time in explaining that much of our knowledge we hold is gained through experience.

Empiricists
Empiricists on the other hand placed their faith on experience. Empiricists believed that only by meticulous observations and methodical experiments could the true knowledge of the world be obtained. John Locke led the way by proclaiming that man is born tabula rasa, a blank slate where sensory experiences of external world are written on. Newton Mechanics, for example, was not discovered through empty speculation as what Rationalist would prefer but observations and experiments. And before the hypothesis is accepted as knowledge it has to stand up the rigor test of Nature which is again observations and experiments. Failure to capture Nature’s whimsical mood means back to the drawing board for the Empiricist to come up with another better hypothesis.

Problem for Empiricists
Empiricism ran into problem when Bishop Berkeley pushed Locke’s empiricistical logic a step further. He questioned that we can ever gain absolute knowledge merely through our senses. Let’s take an apple in our hand. How can we be sure that there is really an apple. The apple we experienced is just a bundle of sensations in synchronism; there is no way that we can affirm there is really an apple out there. An analogy can be enlightening at this point in time. Assuming you get to wear state-of-the-art virtual reality goggle and a high tech gloves that can emit sensations to your hands. In this virtual reality world, you see a living unicorn. Putting your hands over it, you can feel warm and texture of its body, similar to that of a goat or sheep. Because both touch and vision are in synchronism, you have a delusion of a unicorn, alive and running. Through the logic of empiricism, Berkeley has devastated the notion of the external world or matter. However, like a good bishop, God is one person to whom he can fall back on.

David and the Goliaths
Enter David with his sling. Both Empiricism and Rationalism collapsed. What are the stones that David hurled and where is the Achilles’ heel of Empiricism and Rationalism.

The Achilles’ heel of Empiricism and David’s stone
David by pushing empiricism to its logical extreme arrived at conclusion that defies all commonsense. Hume has shown that causality (Achilles heel) is found neither a prior nor a posterior. Some understanding of Hume approach will be helpful.

Impression and Idea
Inherent in us all, we are capable of generating impressions and ideas. Ideas are produced by Impressions and Imaginations, whereas Impressions, by sensory experience. Impressions are often more vivid than Ideas or Ideas are inferior copies of Impression. When you see a red ball, it immediately imprints on your mind as impression. This impression can later to use with other impression as Ideas. For example, you imagine a boy playing with a red ball. This is an idea generated from two impressions-a boy and a red ball. The assumption that Hume made was that all Ideas that we have had could be traced back to its corresponding impressions. Let’s take the mythical unicorn. The Idea of a unicorn can be traced back to two corresponding Impressions which are a horn and a horse.

“Matter of Fact” and “Relation of Ideas” 
Both refer to statements. Relation of Idea refers to statement like “woman is a female human being” or “two plus two equal four” where the predicate can be derived from the subject. Its truth can be verified without recourse to experience; its denial will lead to self-contradiction. Matter of Fact, on the other hand, needs recourse to experience for its veracity. Take this statement “The Prime Minister of Singapore is Goh Chok Tong”. It’s clearly a matter of fact statement which you need to check to confirm its truth, and its denial will not lead to self-contradiction since Gok Chok Tong might not the Prime Minister of Singapore.

Where is this Idea of causality come from?
Causality necessitates the cause of one event will lead to the effect of one event. Hume asks, where is this Idea of causality come from? If one would to look for the corresponding impression, he finds none. If he looks for it in our innate Ideas which often took the form of Maths or Tautology, again he finds none. Then how did this idea of Causality come from? Hume replies gleefully, “your mind.” Let’s take the example of thunder and lighting. For many occasions, it was always the case both lighting and thunder took place in the same area and with the lighting followed by thunder. You hypothesise that lighting is the cause and thunder is the effect; in short, the lighting causes the effect. Although you might find this ludicrous, it is actually the basic principle for doing science. All hypotheses that we have in doing science stemmed from this cause and effect principle which is, based on Hume, cannot be grounded in rationality. Okay, Hume receded, let’s say you can justify the principle of causality but you still haven’t shown that what happened in the past will continue to happen in the future. For the whole of human civilisation, the sun has been dutifully rise everyday to see to our need. But you cannot guarantee that the sun will continue to do so tomorrow. Take another example, before the seventeen century, European thought that all swans are white as they yet then to see a non-white swan.

The argument structure:
Reason : The swans they have seen were white.
Claim : All swans in this world must be white.

This is an inductive argument. The sample of swans the Europeans saw were all white in colour and from this they inducted or reasoned that all swans in this world must be white. It wasn’t until Australia was explored by Europeans did they know the existence of black swans. We have to console ourselves by reminding us that: we are mere finite beings in an infinite world. There is no way where one can take all factors into consideration. Newton did not experiment with every apple tree in this world before generalising that all apples should fall and continue to fall. By the same reasoning, all of us take for granted that the sun would continue to rise tomorrow. Strictly speaking, however, there is always a chance, despite how remote; the sun might not rise tomorrow.

Equally unkind to the Rationalists, Hume regards pure reason as “relation of idea”. It is certain yet useless in explaining the world; and what is useful is yet uncertain.

Hume’s Fork
He mischievously wrote, “If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.”

Hume superior insight has it reverberation felt today. Non-longer we have the deterministic of Newton Mechanics but the probabilities of Quantum theory. We can predict with great precision how many electrons in a beam will scatter when doing Young filter experiment but we can never know precisely which electron will scatter in which direction. And according to Heisenberg Uncertainty Principle, it is a law of nature. This also means that there is a always a possibility, despite how remote, that “impossible” events to happen. For example, there is a possibility that I might just vanish from Earth and reappear on Mars. But for such event to occur, it might take longer than the lifetime of the universe.

To be continued…