'There are no ideas, which occur in metaphysics, more obscure and uncertain, than those of power, force, energy or necessary connexion, of which it is every moment necessary for us to treat in all our disquisitions. We shall, therefore, endeavour, in this section, to fix, if possible, the precise meaning of these terms, and thereby remove some part of that obscurity, which is so much complained of in this species of philosophy.' Hume, Enquiry, Section VII Part 1.
'When we look about us towards external objects, and consider the operation of causes, we are never able, in a single instance, to discover any power or necessary connexion; any quality, which binds the effect to the cause, and renders the one an infallible consequence of the other. We only find, that the one does actually, in act, follow the other. The impulse of one billiard-ball is attended with motion in the second. This is the whole that appears to the outward senses. The mind feels no sentiment or inward impression from this succession of objects: consequently, there is not, in any single, particular instance of cause and effect, any thing which can suggest the idea of power or necessary connexion.' Hume, Enquiry, Section VII Part I
Let me outline the view I have been trying to present of Hume's thoughts on causality. (There is plenty of room for other interpretations, I'm afraid).
1. Before philosophizing, we think of causality as applying when one event happens and brings another about.
2. When you observe one event 'causing' another you never perceive any 'necessary connection' linking the two.
3. (2) means you don't derive the idea of 'necessary connection' from sense.
(4. You don't get it either from introspection.)
5. So on empiricist principles, there is no idea of 'necessary connection'.
6. What generates then the illusion (see (1)) that we have such an idea?7. We form a mental habit on the basis of constant conjunctions and project this onto the world.
We ought now to drive our understanding of this argument a little deeper, before moving on to other aspects.
The nature or meaning of 'necessity' is a perennial problem in philosophy. In considering Hume's discussion we will be noting a major line of argument upon it.
One of the key steps in Hume's argument is to say that we can have no real idea of necessary connection, because when we perceive a putatively causal relationship we do not perceive any necessary connection (or actual 'link').
This step is key, because on empiricism principles, if the idea of necessary connection doesn't come from experience, it can't be meaningful.
'It seems a proposition, which will not admit of much dispute, that all our ideas are nothing but copies of our impressions, or, in other words, that it is impossible for us to think of anything, which we have not antecedently felt, either by our external or internal senses.' Hume, Enquiry, Section VII Part 1.
One suggestion made is this: maybe the idea comes not from sense experience but from introspection. - ie not from the 'external' but from the 'internal' senses. We look at the operations of our own mind and see there the operation of the will. Couldn't this be the source of the idea of necessary connection? Might introspection on the operation of our will be the source of our idea of necessary connection? (Another suggestion is this: maybe the source is the sensation we get when we are hit or pushed . I don't address this here.)
Now Hume addresses this suggestion:
'Since, therefore, external objects as they appear to the senses, give us no idea of power or necessary connexion, by their operation in particular instances, let us see, whether this idea be derived from reflection on the operations of our own minds, and be copied from any internal impression. It may be said, that we are every moment conscious of internal power; while we feel, that, by the simple command of our will, we can move the organs of our body, or direct the faculties of our mind. An act of volition produces motion in our limbs, or raises a new idea in our imagination. This influence of the will we know by consciousness. Hence we acquire the idea of power or energy; and are certain, that we ourselves and all other intelligent beings are possessed of power. This idea, then, is an idea of reflection, since it arises from reflecting on the operations of our own mind, and on the command which is exercised by will, both over the organs of the body and faculties of the soul.' Hume, Enquiry, Section VII Part 1.
First Hume considers the suggestion that it is our awareness of our voluntary control over our body that gives us the idea of necessary connection. What he says is that we are indeed conscious of the fact that we can bring things about with the exercise of the will. But we don't know how we do it. And if we are not conscious of that then we can't be said to have from this the idea of necessary connection.
His principle appears to be: you can only have the idea of necessary connection if you can predict what will happen after the first event has happened. And unless you understand how the will works upon the body, you cannot make that prediction.
You can of course make such predictions in the light of experience. But that is not good enough. What we are looking for is the idea of necessary connection, and this entails that if you will be able to predict, on the basis of the idea of the first event alone, what will follow. And in the case of acts of will, you can't.
Hume's objection: you can't predict what will happen following the act of will. He gives three reasons for this conclusion.
First, we don't understand how the will acts on the body.
'[If] by consciousness we perceived any power or energy in the will, we must know ... its connexion with the effect; we must know the secret union of soul and body ...' Hume, Enquiry, Section VII Part 1
Second, we can affect some things with the will but not others (eg, as Hume thought, our heartbeat). But we don't understand why. Hume says that if we truly had the idea of necessary connection as linked on the one hand to the will, we should understand why:
'Secondly ... Why has the will an influence over the tongue and fingers, not over the heart or liver? This question would never embarrass us, were we conscious of a power in the former case, not in the latter. We should then perceive, independent of experience, why the authority of will over the organs of the body is circumscribed within such particular limits. Being in that case fully acquainted with the power or force, by which it operates, we should also know, why its influence reaches precisely to such boundaries, and no farther.' Hume, Enquiry, Section VII Part 1.
Under the second heading, Hume also invites us to consider the case of paralysis:
'A man, suddenly struck with palsy in the leg or arm, or who had newly lost those members, frequently endeavours, at first to move them, and employ them, in their usual offices. Here he is as much conscious of power to command such limbs, as a man in perfect health is conscious of power to actuate any member which remains in its natural state and condition. But consciousness never deceives. Consequently, neither in the one case nor in the other, are we ever conscious of any power. 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.' Hume, Enquiry, Section VII Part 1.
Hume's third argument is that what we actually succeed in doing, when we will something, according to anatomy, is to bring about changes in the nervous system. These changes by a chain of events eventually result in the action we will. This shows we cannot be aware of any power in the will, because if we did we would know what event the volition would bring in its train, and we don't (we rely on anatomy to tell us):
'Thirdly, we learn from anatomy, that the immediate object of power in voluntary motion, is not the member itself which is moved, but certain muscles, and nerves, and animal spirits, and, perhaps, something still more minute and more unknown, through which the motion is successively propagated, ere it reach the member itself whose motion is the immediate object of volition. Can there be a more certain proof, that the power, by which this whole operation is performed, so far from being directly and fully known by an inward sentiment or consciousness is, to the last degree, mysterious and unintelligible? Here the mind wills a certain event. Immediately another event, unknown to ourselves, and totally different from the one intended, is produced: This event produces another, equally unknown: till at last, through a long succession, the desired event is produced. But if the original power were felt, it must be known: were it known, its effect also must be known; since all power is relative to its effect. And vice versa, if the effect be not known, the power cannot be known nor felt.' Hume, Enquiry, Section VII Part 1.
'We may, therefore, conclude from the whole, I hope, without any temerity, though with assurance; that our idea of power is not copied from any sentiment or consciousness of power within ourselves, when we give rise to animal motion, or apply our limbs to their proper use and office. That their motion follows the command of the will is a matter of common experience, like other natural events: But the power or energy by which this is effected, like that in other natural events, is unknown and inconceivable.' Hume, Enquiry, Section VII Part 1
So far, Hume has considered the suggestion that it is from our acts of will in engaging in action that we derive the idea of necessary connection.
He then turns to another possibility, which is that we get it not from acts of will in action, but from acts of will in creation, as when we create 'a new idea'?
'Shall we then assert, that we are conscious of a power or energy in our own minds, when, by an act or command of our will, we raise up a new idea ... ?' Hume, Enquiry, Section VII Part 1
His answer again is that this won't work either, and develops three arguments why not. I won't go into them. They parallel those raised under the previous head.
Again his conclusion is that we cannot get the idea of necessary connection from this source.
[We don't understand such a process of creation, he says; we don't understand why we can create some mental objects but not others; and we don't understand why our powers of creation vary with circumstances.]
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Last revised 13:02:04