by Sharon Kaye
David Hume, An Enquiry Concerning Human Understanding (http://web.mnstate.edu/gracyk/courses/web%20publishing/enquiryIVi.htm)
You claim to know how that billiard ball will behave. But how will you justify this claim? How will you explain your confidence about the future in general? This is known as the problem of induction, because induction is the logic we use in drawing a general conclusion from particular instances.
Spotlight
Einstein would never have dared to question the physics of Newton if it weren’t for Hume. In a letter to a friend, Einstein wrote that he read Hume’s Treatise ‘with eagerness and admiration’ shortly before discovering relativity theory.
What is a cause?
People speak confidently about one thing ‘causing’ another as though they have seen causation with their own eyes. In fact, no one has ever seen causation itself. What we have seen is various events occurring in succession.
Sometimes, when one event succeeds another we make no special connection between the two. For example, suppose a leaf falls from a tree and then a ladybird lands on it. You wouldn’t say that the falling of the leaf caused the ladybird to land on it. The two events occurred together only once – there was no connection between them.
At other times, when one event succeeds another we make a special connection between the two. Consider the following succession of events:
One billiard ball moves across the table, makes contact with another, and then the other ball continues across the table. One billiard ball moves across the table, makes contact with another, and then the other ball continues across the table. One billiard ball moves across the table, makes contact with another, and then the other ball continues across the table. One billiard ball moves across the table, makes contact with another, and then the other ball continues across the table…
We’ve seen this succession of events (and others just like it) so many times that we come to believe it cannot happen any differently. We say that the motion of the first ball ‘causes’ the motion of the second.
If we saw the behaviour of the billiard balls just once, it wouldn’t occur to us to expect it to happen again. Nothing in the two motions themselves suggests necessity. The repetition, however – what Hume calls the ‘constant conjunction’ of events – leads us to believe that it has to happen every time.
It appears, then, that this idea of a necessary connexion among events arises from a number of similar instances which occur of the constant conjunction of these events; nor can that idea ever be suggested by any one of these instances, surveyed in all possible lights and positions. But there is nothing in a number of instances, different from every single instance, which is supposed to be exactly similar; except only, that after a repetition of similar instances, the mind is carried by habit, upon the appearance of one event, to expect its usual attendant, and to believe that it will exist. This connexion, therefore, which we feel in the mind, this customary transition of the imagination from one object to its usual attendant, is the sentiment or impression from which we form the idea of power or necessary connexion. Nothing farther is in the case. Contemplate the subject on all sides; you will never find any other origin of that idea.
David Hume, An Enquiry Concerning Human Understanding (http://www.bartleby.com/37/3/10.html)
Hume insists that causation, the ‘necessary connection between events’ is all in the mind, not in the world.
Have you contemplated it on all sides? Has Hume convinced you? Or do you still believe there are hidden mechanisms in the universe guaranteeing the connection between events?
A rationalist, who believes in the existence of things unseen, has the right to believe in hidden mechanisms. But an empiricist has no such right. Empiricists believe only what they experience. No one has ever experienced such mechanisms. And no one has ever experienced the future. So no one can claim to have any knowledge of how things will behave then.
Hume is an empiricist. His goal is to show that true empiricism requires a lot more scepticism, the attitude of doubt or disbelief, than people realize.
Spotlight
Have you seen Hume’s missing shade of blue? As an empiricist, Hume says all ideas are copies of what we perceive. Yet we can have an idea of a shade of blue we have never seen that lies on the spectrum between two shades we have seen. How is this possible unless we have an inner source of ideas?
Case study: rationalists vs. empiricists
The authors we have examined so far in this book have been lining up on either side of the epistemological divide: Plato, Anselm and Descartes the rationalists; Aristotle, Aquinas, Hobbes, Locke, Berkeley and Hume the empiricists.
Baruch Spinoza (1632–77) and Gottfried Wilhelm von Leibniz (1646–1716) are two seventeenth-century philosophers who earned a place on the rationalist side. They weigh in on the problem of induction in an interesting way.
Leibniz argues that the laws of physics guarantee causal connections because they are based on the necessary natures of things. So, for a billiard ball to be a physical object is for it to act with an equal and opposite reaction. If it didn’t, it wouldn’t be what it is. And physical objects have to be what they are, in Leibniz’s view, because they were made by God. As the best of all possible beings, God must create the best of all possible worlds. God gave physical objects the nature he did because this is the best possible nature they can have. Therefore, their predictable behaviour is necessary.
Spinoza regards the behaviour of the billiard ball as equally necessary, but for a different reason. In Spinoza’s view, the infinity of God implies that God is everything. According to this philosophical pantheism, all of nature, including every physical object, is part of God. But God’s infinity also implies that he must do exactly as he does – there is no left over room, so to speak, for him to do any differently. Therefore, all physical objects act with the same necessity.
In the end, theism guarantees the laws of physics for both Leibniz and Spinoza. Having barred theism from scientific reasoning on the grounds that theism involves things unseen, Hume is left without any such guarantee.
Relations of ideas vs. matters of fact
Hume supports his scepticism by arguing that all our experience produces knowledge that can be divided into two different categories.
1 Relations of ideas are logical truths, such as ‘two plus two equals four’. These are necessary because the attempt to deny them results in a contradiction. If two plus two equalled five, then one plus one plus one plus one is not one plus one plus one plus one, which is a contradiction.
2 Matters of fact are observed truths, such as ‘bread nourishes’. These are contingent (meaning ‘not necessary’) because you can deny them without producing a contradiction. The idea of bread poisoning instead of nourishing involves no conceptual impossibility. We can prove this by imagining a world where bread poisons instead of nourishes.
Hume points out that the assertion ‘A causes B’ is a matter of fact, not a relation of ideas. Therefore it can’t be necessary.
Of course, everyone recognizes instances when matters of fact go differently from usual. We’ve all eaten something that usually nourishes us, only to find that, this time, it made us sick. When this happens, we are liable to look for a hidden cause – some microscopic bacteria in the food that gave us food poisoning.
But when Hume calls the nourishing effect of bread a matter of fact, he isn’t saying that there may be hidden causes that make things turn out differently this time. He’s saying that the bread could suddenly have a completely different effect without any different causes at all.
To insist that there would have to be different cause in order to produce a different effect would be to cast the nourishing effect of bread as a relation of ideas like ‘two plus two equals four’. Because human beings are creatures of habit, we constantly view causal connections as logical connections. But this is a conceptual confusion we must overcome, in Hume’s view.
It’s not as though Hume recom
mends that we begin each day without any expectation of bread nourishing, the sun rising or gravity holding. In our daily lives we can continue to expect the succession of events we have grown so accustomed to. But by applying scepticism towards all things unseen, including the supposed ‘laws of nature’, we will think more clearly and be less likely to develop a mistaken understanding of the world.
Miracles
Ironically, Hume’s rejection of causal necessity did not make him any more inclined to accept the occurrence of miracles. In fact, he felt that religion as a whole, which is largely based on miracles, presents a mistaken understanding of the world.
Hume defines a miracle as ‘a transgression of a law of nature by a particular volition of the Deity, or by the interposition of some invisible agent’.
It may seem strange to hear Hume speak of ‘laws of nature’ after seeing him argue so vigorously against their existence. But, naturally, Hume doesn’t want to deprive scientists of a very useful way of speaking about the causal patterns we’ve experienced. He simply redefines the idea of a law of nature as a codified description of the past behaviour of physical objects.
So a miracle is a supernatural break in the usual causal pattern we’ve experienced. Hume uses the strong language of ‘transgression’ because, while rejecting causal necessity, he still takes experience very seriously. Recall that, for an empiricist, experience is the basis of all our reasonable belief. And a miracle violates the expectations we form on the basis of experience. Thus, it cannot be reasonably believed.
Suppose someone claims to have witnessed a man raised from the dead. Hume asks us to consider how many times we have ever experienced such a thing occurring. He then asks us to consider how many times we have ever experienced someone lying to us or being mistaken about something they tell us. We should then decide to believe whichever we have experienced more often. While it isn’t impossible for this decision to be wrong, it isn’t reasonable to base our beliefs on anything else.
Hume offers a thought experiment to support his argument. Imagine an Indian prince who refuses to believe that water can freeze because he grew up in a hot country where he was never able to witness such an event occurring. The prince is reasoning correctly in Hume’s view, because he is following empiricist principles. The prince would need to gain a good amount of experience with freezing water before believing in it.
While at first it may seem that Hume’s denial of causal necessity should leave him especially open to miracles, on closer examination we see that his underlying scepticism provides a basis for questioning both causal necessity and miracles. It provides a basis for questioning many other things as well.
The bundle theory of personal identity
Hume did not believe in life after death. Such an occurrence would be a miracle, after all, and an anchor for the religious world view that he found so contrary to sound empirical thinking. Freed from religious motives, Hume’s investigation of the question of how the self endures led to radical results.
We saw in the previous chapter how Locke’s belief in life after death led him to the memory criterion of personal identity. Seeing problems with the endurance of both the body and the soul, Locke concluded that our consciousness is what endures – in the form of memory.
Hume was intrigued by the idea that an enduring consciousness is introspectively observable. As an empiricist, after all, Locke would not be entitled to believe he had an enduring consciousness at all unless he experienced it. Evidently, Locke was convinced that he did experience his self when he thought about his own thinking – remembering the experiences he has over time.
Hume, however, denies that reflection upon current or past experiences adds up to anything more than a bundle of perceptions. Hume’s claim that what we call our ‘self’ is really nothing but a series of particular experiences has come to be known as the bundle theory of personal identity.
How extraordinary for Hume to conclude that he has no enduring self! And yet, if you take a moment to reflect on your own thinking, you may be hard pressed to disagree.
For my part, when I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe any thing but the perception. When my perceptions are removed for any time, as by sound sleep, so long am I insensible of myself, and may truly be said not to exist. And were all my perceptions removed by death, and could I neither think, nor feel, nor see, nor love, nor hate, after the dissolution of my body, I should be entirely annihilated, nor do I conceive what is further requisite to make me a perfect nonentity. If anyone, upon serious and unprejudiced reflection, thinks he has a different notion of himself, I must confess I can reason no longer with him. All I can allow him is, that he may be in the right as well as I, and that we are essentially different in this particular. He may, perhaps, perceive something simple and continued, which he calls himself; though I am certain there is no such principle in me.
David Hume, A Treatise of Human Nature (http://andromeda.rutgers.edu/~jlynch/Texts/treatise.html)
Locke claimed that, when he remembered the past, he accessed the same consciousness as he had at that time. Is it really the same? When you remember the day you graduated from high school, for example, do you have the same consciousness as you had then, or just a similar one? Does it need to be the same in order for you to be the same person as that high-school student? These questions remain unresolved.
Key ideas
Bundle theory of personal identity: That what we call our ‘self’ is really nothing but some particular experience or other
Causation: The necessary connection between events
Constant conjunction: The repetition of events that gives rise to the idea of causal necessity
Matters of fact: Observed truths, such as ‘bread nourishes’
Miracle: A transgression of a law of nature by a particular volition of the deity, or by the interposition of some invisible agent
Pantheism: That all of nature, including every physical object, is part of God
Problem of induction: How do we justify our claim to know how things will behave in the future?
Relations of ideas: Logical truths, such as ‘two plus two equals four’
Scepticism: The attitude of doubt or disbelief
Fact-check
1 Which of the following does Hume observe when he introspects?
a His self
b Particular perceptions
c His soul
d God
2 For Hume, the idea of a necessary connection among events arises from which of the following?
a Constant conjunction
b Consciousness
c Matters of fact
d Relations of ideas
3 Suppose a scientist was speaking about the law of gravity. In which of the following ways would Hume be most likely to respond?
a He would warn that the law of gravity does not exist
b He would interpret the law of gravity as a record of past experience
c He would infer that gravity will hold in the same way in the future
d He would complain that he doesn’t understand what the scientist means
4 Which of the following is entitled to believe in laws of nature?
a Empiricists
b Rationalists
c Materialists
d Idealists
5 Which of the following provides the foundation for Hume’s philosophy?
a Religion
b Rationalism
c Billiards
d Scepticism
6 For Spinoza, causal necessity is implied by which of the following?
a God’s infinity
b God’s perfection
c Human imagination
d The constant conjunction of events
7 Which of the following is a reported miracle likely to be, according to
Hume?
a A lie
b A transgression of the laws of nature
c A matter of fact
d A hidden mechanism
8 Which of the following does Hume deem necessary?
a The laws of nature
b Causal connection
c Matters of fact
d Relations of ideas
9 Which of the following is a matter of fact, in Hume’s view?
a That we perceive the self when we introspect
b That no one has experienced the future
c That two plus two equals four
d That fire burns
10 Why is induction a problem?
a Because no one knows what it really means
b Because it defies the laws of nature
c Because it is hard to justify the inference
d Because no one has ever experienced a miracle
Dig deeper
Paul Stanistreet, Hume's Scepticism and the Science of Human Nature (Ashgate, 2002)
Saul Traiger, The Blackwell Guide to Hume's Treatise (Blackwell, 2006)
John P. Wright, The Sceptical Realism of David Hume (University of Minnesota Press, 1983)
9
Kant and duty
‘Good will shines forth like a precious jewel.’
Immanuel Kant
In this chapter you will learn:
• why Kant thinks it is always wrong to lie
• how Kant reconciles rationalism and empiricism
• about transcendental idealism, Kant’s revolutionary thesis