On Hume’s Theory of The Independent Existence of Objects
Michael Vossen

Hume, in his A Treatise of Human Nature, attempts to explain the belief that we experience objects that exist continuously and distinct from ourselves. In this paper I will reconstruct Hume’s argument, while critically discussing elements of which that are problematic. In particular, I will argue that Hume needs a more complete argument for the impossibility of reason to arrive at the belief in the continued existence of objects, and that we should be critical of Hume’s use of the idea of coherence.

First, I will explain why Hume even needs to give an explenation of our beliefs in objects. Hume acknowledges that most people believe in the independent existence of external objects, and in the persistence of objects over time. Hume knows that if his theory of ideas commits us to ideas that go against common sense, such as the denial of our beliefs about objects, then there is reason to abandon his theory of ideas. This is because Hume’s theory of ideas holds that all ideas come from impressions.(4) Further, Hume claims “An opinion, therefore, or belief may most accurately be defin’d, A LIVELY IDEA RELATED TO OR ASSOCIATED WITH A PRESENT IMPRESSION.”(96) So given that a belief is a kind of idea, and all ideas come from impressions, it follows that all meaningful beliefs come from impressions. Thus explaining how our beliefs in objects come arise from some association with impressions is an important task for Hume, as such an explanation is needed to maintain his theory of ideas.
Hume maintains that the belief in the independent existence of external objects, and the belief about the persistence of objects over time can captured by the beliefs that objects exist continuously, and that objects exist distinctly. This is why Hume asks his reader to consider “Why we attribute a CONTINU’D existence to objects, even when they are not present to the senses; and why we suppose them to have an existence DISTINCT from the mind and perception”.(188) Hume thinks answering these questions will explain our beliefs about objects, When Hume says that objects have a continued existence, he can be taken to mean that objects exist even when not perceived. Likewise, the claim that objects have a distinct existence means that the objects are distinct from the mind; external objects are not mental entities.

Hume thinks the ideas of being distinct and of being continuous are related such that “…the decision of the one question decides the other…”(188) As such, Hume appears to hold that an object is distinct if and only if an object is continuous. An argument for this claim might go as such. Suppose some objects exist continuously. Does it follow that they exist distinctly? Yes, for if an object exists continuously, it exists even when the mind is not focused on it, and even if the mind were to disappear completely. Since to be distinct is to not be a mental entity, and continuously existing objects exist apart from the mind, then continuously existing objects are not mental entities. So, continuously existing objects also exist distinctly, and therefore if an object exists continuously, then an object exists distinctly.

This is to establish one half of the bi-conditional. Now let us consider the other half. Suppose some objects are distinct. Does it follow that the objects are also continuous? No, for while the objects might exist independently of the mind, they might go out of existence when not perceived and come into existence right before being perceived. Since to exist continuously is to exist even when not perceived, and some objects might exist distinctly yet not exist when not perceived, some objects can be exist distinctly but not continuously. So it is not the case that if an object is distinct then the object is continuous.

Despite Hume being incorrect about the relation between being continuous and being distinct, his arguments from an object being continuous to the object being distinct are still valid. So, in examining Hume’s arguments, I will focus solely on those that regard the belief that objects have a continuous existence.

Hume uses an argument by elimination to establish which human faculty produces the belief in continuous existence. Hume asks “…whether it be the senses, reason, or the imagination that produces the opinions of continu’d, or of distinct existence”(188)Logically speaking however, the possibilities include belief arising from sense, reason, imagination, or neither of the three. If the latter possibility holds, then there is a belief that arises from none of these faculties. And since to believe is just to have a lively idea, and Hume’s theory of ideas holds that “all ideas come from impressions”, Hume’s theory holds that if there is a belief, then there is some impression from which the belief arose from. So, if the latter possibility holds, then there is a belief that came from no impression, so by modus tolluns on the claim “ if there is a belief, then there is some impression from which the belief arose from”, there should be no such belief. Since there would be a belief that did not come from some impression, and Hume’s theory holds that there is no such belief, by this contradiction we might reject Hume’s theory of ideas. Having established the form of Hume’s argument, I will now examine Hume’s arguments for each supposition.

The first supposition is that sense produces the belief in an object’s continued existence. Hume quickly rejects this supposition, writing “For that is a contradiction in terms, and supposes that the senses continue to operate, even after they have ceas’d all manner of operation.”(188) Hume’s argument might be drawn out more. Suppose the sense produce the belief in continued existence. Then the sense produce the belief that an object exists even when not perceived. Since all beliefs arise from impressions, this particular belief must arise from an impression, namely, the impression of an object existing when not perceived. But to have such an impression is to perceive an object existing when not perceived. Since the object cannot be both perceived and not perceived, the supposition that sense produces the belief in continued existence leads to a contradiction. Thus, it is not by sense that we have the belief in continued existence.

As argued, distinct existence does not imply continued existence, so I will ignore Hume’s arguments regarding distinctness. For even if we establish that distinctness arises from the senses, we will still have the belief in the continued existence of objects, whose origin must be explained for Hume’s account to succeed. So I will move on to the next faculty.
Does the belief in an object’s continued existence come from reason? Hume writes that “…we can attribute a distinct continu’d existence to objects without ever consulting REASON, or weighing our opinions by any philosophical principle.”(193) and that “…these arguments [about object’s continued existence] are known but to very few, and that ‘tis not by them, that children, peasants, and the greater part of mankind are induc’d to attribute objects by some impression, and deny them to others.”(193) While Hume is no doubt correct that the belief in the continued existence of objects arises before we consider arguments towards it, Hume’s claim might strike us as controversial in that it apparently assumes reasons or arguments for a belief must be known to us before we can be said to have the belief by those arguments. In other words, we might question why we have beliefs that come from an unconscious use of reason on other of our ideas or impressions.

Hume might avoid this objection if he can establish that no possible use of reason could give us the belief in an object’s continuous existence. For if this is the case, then even an unconscious use of reason could not establish such a belief. Hume appears to think that no possible use of reason can lead to the belief in an object’s continuous existence, for he writes “So that upon the whole our reason neither does, nor is it possible that it ever shou’d, upon any supposition, give us an assurance of the continu’d and distinct existence of body”(193) To hold that no supposition can possibly be reasoned from to the conclusion that object’s exist continuously is a rather strong claim, and we should be skeptical of it without a good argument. Further, the claim strangely clashes with his statement “…these arguments [about object’s continued existence] are known but to very few”(193) Hume must regard these arguments as false then.
Hume’s argument appears to rely on two claims. The first is that “…as long as we take our perceptions and objects to be the same, we can never infer the existence of one from that of the other…”(193) Further, the second is that “Even after we distinguish our perceptions from our objects, ‘twill appear presently, that we are still incapable of reasoning from the existence of one to that of the other…”(193) These claims do nothing to establish his conclusion however, and appear to merely hold that it is impossible reason from our perceptions to the existence of an object, whether the perceptions be the object, or the perceptions to be distinguished from the objects, which seems to be just a restatement of his conclusion.

Hume’s claim would be better argued for if he reminded us the powers he ascribes to reason. Hume seems to think that reason cannot give us any new ideas, and is only an ability to make distinctions about the ideas we are given.(164, 124) Further, Hume thinks it a mistake of the vulgar to think that the objects presented to them are anything more than impressions.(193) So, Hume might think that reason cannot give us the idea of continued existence, for the idea of continued existence would have to be part of some complex idea that could be separated off, and Hume has already argued that the idea of continued existence could not arise from a simple idea. This argument does rely on Hume’s conception of reason however, and we might doubt whether reason only has the powers Hume ascribes to it.

Having eliminated the other capacities, and needing to maintain his theory of ideas, Hume writes “That opinion [of continu’d existence] must be entirely owing to the IMAGINATION”(193) By imagination, Hume means the capacity to present ourselves with thoughts. Other than allowing us to combine thoughts in our head, as when we day dream about unicorns and dragons, the imagination also presents us with a lively connection between thoughts, as when a thump is expected after repeated droppings of a book. In particular, Hume thinks “…the continu’d existence of body depends on the COHERENCE and CONSTANCY of certain impressions…”(195) The belief in the continued existence of objects can thus be thought of as an involuntary belief needed to make the world coherent. We fill in the gaps of our experience of the world using reasonable causal hypothesis, one of which is the belief that object’s exist continuously.

This explanation might seem more plausible if we recall that for Hume, having a belief is a natural matter, of habit or instinct. So, the hold of a belief is not rational, and after pondering skeptical arguments that make us doubt the existence of necessary connections in the world, such as the thought that a billiard ball might actually turn into a bird upon strike of cue, or that I will not fall through the ground upon my next step, Hume thinks our beliefs that these events won’t occur will thankfully come back to us. Thus it makes sense under Hume’s theory that beliefs be a certain instinct.

We might object to Hume account at this point insofar as he brings in the idea of coherence. Using Hume’s method of argument, we might ask where we ever get the idea of coherence? For to have an idea of coherence seems to be to think of the parts of one’s experience as consistent with the other parts within the whole of experience. So, in order to have the idea of coherence, we need the idea of something as a whole, and of consistent. But since our experience is always of many particular indivisible impressions, which impression is the impression of a whole?(38) Further, if we invoke the notion of a complex idea to try to explain the origin of the idea of wholeness, we appear to assume the idea of wholeness, for complex ideas are simply those which can be distinguished into parts, and we might ask what the parts are of.(2) To answer that they are parts of a whole is to use the idea of wholeness in forming the idea of a complex idea. Finally, since simple ideas have no parts, they cannot be the origin of the idea of a whole, for a whole is something with parts. So Hume needs a better account of where we get the idea of coherence to answer to such objections.


Works Cited

Hume, David. A Treatise Of Human Nature. Eddited by L.A. Selby-Bigge. Oxford University Press, 1978.