Hume seems to think he doesn't need it, that you can coherently say 'impression' and dodge the question, "Impression of what?" — Srap Tasmaner
The argument goes round, that the hypothesis of 'double existence' is insupportable, which would be true if impressions are the same as ideas. But is that claim based only on introspection? Or does it arise from a methodological choice not to consider the 'what' that impressions are of? (Here I really have to reread.) — Srap Tasmaner
This is the argument based on his account of our judgments of cause and effect being derived from the experience of constant conjunction. He argues that the claim that some object causes our perceptions cannot be accepted because we never have the opportunity to observe the object, on the one hand, accompanied by the perception, on the other, much less constantly. — Srap Tasmaner
"...I explain only the manner in which objects affect the senses, without endeavouring to account for their real nature and operations.... my intention never was to penetrate into the nature of bodies, or explain the secret causes of their operations... I'm afraid such an enterprise in beyond the reach of human understanding, and that we can never pretend to know otherwise than by those external properties, which discover themselves to the senses."
pp.111-112 in the Penguin Edition of Humes Treatise
There are other quotes, but it would be a bit long to provide them here. The point is to state, that Hume did not think that all there was to causality is constant conjunction (this is frequently claimed, it's not true), it's that it's the only thing we can discover about it. We know not the "secret springs" of nature. — Manuel
Every instance, it seems to me we have a different perception — Manuel
that neither reason nor observation justify us explaining these resemblances by positing a constant object they are perceptions of. — Srap Tasmaner
tis in vain to ask — Manuel
We may well ask, What causes induce us to believe in the existence of body? but 'tis vain to ask, Whether there be body or not? That is a point, which we must take for granted in all our reasonings.
That idea, when conjoin'd with the idea of any object, makes no addition to it.
We may observe, that 'tis universally allow'd by philosophers, and is besides pretty obvious of itself, that nothing is ever really present with the mind but its perceptions or impressions and ideas, and that external objects become known to us only by those perceptions they occasion.
Now since nothing is ever present to the mind but perceptions, and since all ideas are deriv'd from something antecedently present to the mind [ argued earlier ]; it follows, that 'tis impossible for us so much as to conceive or form an idea of any thing specifically different from ideas and impressions.
The farthest we can go towards a conception of external objects, when suppos'd specifically different from our perceptions, is to form a relative idea of them, without pretending to comprehend the related objects. Generally speaking, we do not suppose them specifically different; but only attribute to them different relations, connexions and durations. But of this more fully hereafter.
For as to the notion of external existence, when taken for something specifically different from our perceptions, we have already shewn its absurdity.
we can't raise the question of external objects — because Nature — but we can look for causes of the belief we're stuck with. — Srap Tasmaner
nature has made this issue too important to leave it to us to decide if objects ("body") exist or no — Manuel
Nature has not left this [ the principle of the existence of body ] to his [ the sceptic's ] choice, and has doubtless [ ! ] esteemed it an affair of too great importance to be trusted to our uncertain reasonings and speculations.
Nature, by an absolute and uncontroulable [ by us ] necessity has determin'd us to judge as well as to breathe and feel. ... Whoever has taken the pains to refute the cavils of this total scepticism, has really disputed without an antagonist, and endeavor'd by arguments to establish a faculty, which nature has antecedently implanted in the mind, and render'd unavoidable.
Not so for the external existence of objects. There has been nothing yet to explain why nature implanted this habit in us, why the belief in external objects is so necessary. What do we get out of this belief of such great importance that nature implanted it in us? — Srap Tasmaner
It is curious that he treats reasoning (with the principle example being mathematics) and the belief in distinct, persistent, external objects as separate questions, albeit giving them related answers. In the post-Frege world, we might naturally think these go together. We carve up the world into classifiable objects to make it safe for logic; conversely we analyze the world using the logic of predicates and classes because we have carved it up into distinct objects with properties in common. Logic and objects go together. Without distinct objects, there is nothing for the functions of logic (not the predicates, not the truth functions, quantifiers, or other operators) to be applied to. — Srap Tasmaner
we do not know — Manuel
why we would hold questionable beliefs and continue to hold them once shown to be groundless — that requires some explanation. — Srap Tasmaner
So perhaps my wondering 'what we get out of it', why nature would so order things, is misplaced. That nature does so order our minds is all Hume is trying to show.
Plausible? — Srap Tasmaner
On the whole, I find your reading of him to be quite accurate — Manuel
There it is claimed, first, that since to conceive of any thing is to conceive of it as existing, existence is not a distinct idea at all, not a separable perception:
That idea, when conjoin'd with the idea of any object, makes no addition to it. — Srap Tasmaner
The Critique of Pure Reason, Section IV.Being is evidently not a real predicate, that is, a conception of something which is added to the conception of some other thing. It is merely the positing of a thing, or of certain determinations in it. Logically, it is merely the copula of a judgement. The proposition, God is omnipotent, contains two conceptions, which have a certain object or content; the word is, is no additional predicate—it merely indicates the relation of the predicate to the subject. Now, if I take the subject (God) with all its predicates (om- nipotence being one), and say: God is, or, There is a God, I add no new predicate to the conception of God, I merely posit or affirm the existence of the subject with all its predicates—I posit the object in relation to my conception. The content of both is the same; and there is no addition made to the conception, which expresses merely the possibility of the object, by my cogitating the object—in the expression, it is—as absolutely given or existing. Thus the real contains no more than the possible.
The sceptic must assent to the principle concerning the existence of body ... Nature has not left this to his choice. — "
That idea, [existence] when conjoin'd with the idea of any object, makes no addition to it.
But attributing, like relating or associating -- these don't sound like perceptions but ways of handling or working with or acting upon perceptions. We can, in addition, have ideas about what we're doing when do this sort of thing, and Hume bundles some of these mental behaviors together and calls them our notion of external existence. — Srap Tasmaner
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