Sense data according to Hume

Here is a different version of the sense-datum argument from the one you probably learned in the history books.

(1) Although this object looks circular, it is not circular (it's elliptical)
(2) Plates are not elliptical
(3) This object is not a plate
(4) We'll call it a sense-datum
(5) There is nonetheless an actual plate corresponding to the sense-datum.

The argument is valid, unlike the sense-datum arguments parodied and rejected by philosophers like Austin. It starts right away with the premiss that this thing, which you took to be a plate, is not circular at all. It looks circular, but isn't. And if plates are circular, it clearly can't be a plate.

Is the argument sound? Is the first premiss true? Why do we think that the sense-datum is not circular, even though it looks circular? Hume tells us (in connection with a different example, in the Treatise, Book I part iv sec. 2 "Of Scepticism with regard to the Senses") that we come to this 'by reflection' or by 'studied reflection'. Imagination or 'fancy' suggests that the datum is circular, that it is just the way it looks. Reason or reflection tells us that it is not circular. For example, we can look at the datum as an artist sees it and as he represents it in a flat picture, as an ellipse.

The final step of the argument is curious. Why do we suppose there is anything circular there at all? Hume has an interesting theory about this. I paraphrase him as follows. There is naturally an opposition between the two mental forces of imagination and reason, for they are telling us contradictory things. Imagination suggests the datum is circular. Reason and reflection tell us it is not. To set ourselves at ease, we invent a new theory which seems to reconcile both: the philosophical system (i.e. the representative theory of perception) that posits the double existence of the sense-datum and its external object. This satisfies our reason in allowing that the sense-datum is not circular, while agreeing with our imagination in attributing the circularity to something else, which we call an 'object'.

This philosophical system, therefore, is the monstrous offspring of two
principles, which are contrary to each other, which are both at once embrac'd by
the mind, and which are unable mutually to destroy each other.

The imagination tells us, that sense-data have all properties that we commonly suppose them to have (plate sense-data are round, sense-data of straight sticks in the water really are straight). Reflection tells us that they really do not have thise properties. We escape the contradiction between these opinions by a fiction which conforms to both reflection and fancy, by ascribing the contrary features to different things - such as the circularity to the object, the ellipticality to the datum.

Not being able to reconcile these two enemies (reason and fancy), we try "to set ourselves at ease as much as possible, by successively granting to each whatever it demands, and by feigning a double existence, where each may find something, that has all the conditions it desires". Were we fully convinced that the datum was circular we would never run into this idea of a double existence, since we would find satisfaction in the first supposition, without looking any further. Again, if we were fully convinced that the datum was elliptical, we would be as little inclined towards the theory of double existence, since in that case we would clearly perceive the error of the belief that it was circular, and would not bother with it any more.

'Tis therefore from the intermediate situation of the mind, that this opinion
arises, and from such an adherence to these two contrary principles, as makes us
seek some pretext to justify our receiving both; which happily at last is found
in the system of a double existence.

Absolutely my favourite bit of Hume.

Is it cruel to believe in Hell?

Is the belief cruel? You might say that God is cruel. But is the person who believes this of God also cruel? Why? If God does not exist, no one has or will be punished, and so no one is hurt. If God exists, but does not intend to punish souls in this way, the same applies. Cruelty can only exist when there is an object of cruelty.

But if God exists and does intend punish souls in this way, then that is the fact of the matter. There is nothing that the believer can do to prevent the suffering.

David Hume had the interesting theory that all professed believers are really atheists. He says that all Catholics condemn the St Bartholomew's massacre as cruel and inhumane. Yet these are the same people, he says, who condemn non-Catholics to eternal torment 'without scruple'.

Currently being discussed at the Quodlibet forum.

Is Hume an eliminativist about objects?

Hume's philosophy is more radical than we imagine. He did not hold, as Locke held, a representative theory of perception such that our sense impressions are fleeting and perishable, but are representative of objects which are relatively permanent and durable. He held that, when we analyse and examine the world carefully, we find that the things we call tables, chairs and houses really cease to exist when we are not perceiving them. For such things are really identical with our perceptions or sense impressions. He says* "it is impossible for us distinctly to conceive, objects to be in their nature any thing but exactly the same with perceptions". But "it is a gross illusion to suppose, that our resembling perceptions are numerically the same; and it is this illusion, which leads us into the opinion, that these perceptions are uninterrupted, and are still existent, even when they are not present to the senses. " Only philosophical analysis can penetrate and expose this illusion. Even that analysis can fail. The illusion is so strong that as soon as philosophers have discovered it - namely discovered, like Locke and the seventeenth century philosophers of perception, that our sense-impressions are fleeting and impermanent - that they immediately invent a new set of impressions that have the required permanence. Thus the representative theory at once refutes and re-establishes the illusion.

[...] it is liable to the same difficulties; and is over-and-above loaded with this absurdity, that it at once denies and establishes the vulgar supposition. Philosophers deny our resembling perceptions to be identically the same, and uninterrupted; and yet have so great a propensity to believe them such, that they arbitrarily invent a new set of perceptions, to which they attribute these qualities.

Does this make Hume an eliminativist, or a reductionist? I have argued elsewhere that the distinction is arbitrary, and I shall argue that this applies to Hume's position also. If we define 'material object' as something which is mind-independent and permanent, then it is clear Hume is denying the existence of any such things. The only objects we are aware of, he says, are these fleeting and perishable sense-impressions, which have no continued and uninterrupted existence. So he is an eliminativist regarding material objects defined in this way. But as I have argued, we don't have adopt this definition. If we define 'material object' as something identical with our sense-impression, then uninterrupted existence turns into a mere accidental feature of objects. An accidental feature that, as Hume argues, may not apply to any object at all, just as 'carried by the ether' does not apply to light, as people once thought.

In summary: whether Hume is an eliminativist or reductionist about the term 'material object' depends entirely on how you choose to define the term. There are the observable phenomena - the sense impressions - and there is whatever unobservable X explains or underlies these phenomena. And that X can have any features you like. There are no 'essential features' of things that are essentially unobservable.

* A Treatise of Human Nature, Book I. 4. ii - "Of scepticism with regard to the senses". This section is essential reading for any understanding of Hume. People often don't read it because it occurs towards the end of the first book, and because there is a lot of focus on the causation stuff in Part III. Part IV, particularly sections 2-4, are by far the most interesting and enjoyable and indeed strange parts of the work.