Locke and Hume on Belief, Judgment and Assent
Locke and Hume on Belief, Judgment and Assent*
David Owen
Part One: Introduction
In 1.3.5, when Hume launches his investigation of causal reasoning, and his account of how we come to believe in unobserved objects, on the basis of observed ones, he subdivides what needs to be explained into three parts:
First, The original impression. Secondly, The transition to the idea of the connected cause or effect. Thirdly, The nature and qualities of that idea. (T 84) [1]
Hume raises the first issue only to set it aside. We do not and cannot know the ultimate causes of our impressions of the senses. The second issue is a matter of explaining how we get from the observed impression to the unobserved idea. Hume explains this transition by appeal to the association of ideas in Section vi, "Of the inference from the impression to the idea". The third issue remains: “The nature and qualities of that idea”, i.e., Hume must explain what it is to believe something rather than simply have the idea occur in the imagination. Hume’s answer is disarmingly simple. Just as impressions and ideas “differ from each other only in their different degrees of force and vivacity”, so too a belief differs from a mere idea only because of its additional force and vivacity.” The extra force and vivacity of a belief comes from the impression with which the idea is associated, so the official definition of belief becomes: “A lively idea related to or associated with a present impression.” (T 96)
Hume’s account has been much reviled, especially when it is considered, as Hume intended it to be, as an account of judgment and assent as well as belief. Consider the following important footnote:
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Locke and Hume on Belief, Judgment and Assent
We may here take occasion to observe a very remarkable error, which, being frequently inculcated in the schools, has become a kind of establish’d maxim, and is universally received by all logicians. This error consists in the vulgar division of the acts of the understanding, into conception, judgment, and reasoning, and in the definitions we give of them. Conception is defin’d to be the simple survey of one or more ideas: Judgment to be the separating or uniting of different ideas: Reasoning to be the separating or uniting of different ideas by the interposition of others, which shew the relation they bear to each other. But these distinctions and definitions are faulty in very considerable articles. For, first, ‘tis far from being true, that in every judgment, which we form, we unite two different ideas; since in that proposition, God is, or indeed, any other, which regards existence, the idea of existence is no distinct idea, which we unite with that of the object, and which is capable of forming a compound idea by the union. Secondly, as we can thus form a proposition, which contains only one idea, so we may exert our reason without employing more than two ideas, and without having recourse to a third to serve as a medium betwixt them. We infer a cause immediately from its effect; and this inference is not only a true species of reasoning, but the strongest of all others, and more convincing than when we interpose another idea to connect the two extremes. What we may in general affirm concerning these three acts of the understanding is, that taking them in a proper light, they all resolve themselves into the first, and are nothing but particular ways of conceiving our objects. Whether we consider a single object, or several; whether we dwell on these objects, or run from them to others; and in whatever form or order we survey them, the act of the mind exceeds not a simple conception, and the only remarkable difference, which occurs on this occasion, is, when we join belief to the conception, and are perswaded of the truth of what we conceive. This act of the mind has never yet been explain’d by any philosopher; and therefore I am at liberty to propose my hypothesis concerning it; which is, that ‘tis only a strong and steady conception of any idea, and such as approaches in some measure to an immediate impression. (T 96-97, footnote)
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Locke and Hume on Belief, Judgment and Assent
There are several remarkable things about this passage, but for the moment let us just note the following. Judgment, especially judgments about existence, need not be a matter of predicating one idea of another. “God exists” appears to be “a proposition, which contains only one idea”. Thus Hume wants to resolve judgment into conception, though he recognizes that there is “a remarkable difference” between what happens when we merely conceive of something, and “when we join belief to the conception, and are perswaded of the truth of what we conceive.” For Hume, to believe something is to assent to it as true, and to give an account of belief is to give an account of judgment. Hume wants to discuss “the nature of belief, or the qualities of those ideas we assent to” (T 94). Though a belief is an idea conceived of in a certain way, it is clear that Hume frequently uses the term “belief’ to pick out what it is about an idea, when it is believed, that distinguishes it from ideas that are merely conceived. Used in this way, >belief’ means just what >assent’ means.[2]
A colleague of mine, when giving a course on >the judgment problem’, started off with what he called “Hume’s spectacularly inadequate account,” while another described Hume’s account of belief as “appalling.” Barry Stroud, referring to the long footnote at T 96-97, just quoted, claims that because Hume “sees judging as just a special case of an object’s being present to the mind... he does not see the special difficulties that creates. And he does not see that without an account of how ideas combine to make a judgment or a complete thought he can never explain the different roles or functions various ideas perform in the multifarious judgments we make, or in what might be called the >propositional’ thoughts we have.” [3] It is clear what is held to be inadequate in Hume’s account. No >single idea’ theory can hope to account for what it is to predicate one idea of another, to form a complete thought with propositional structure. A fortiori, no such theory can account for what it is to assent to such a proposition. On the other hand, as we have seen in the long footnote, Hume is perfectly aware that the standard account of judgment involves “the separating or uniting of different ideas,” or what we would now call predication. He explicitly rejects this account, in favour of his own. This is not some simple oversight or unawareness of the problems that it will bring. In fact, Hume recognizes that by reducing judgment to conception, he is left with the difficulty of accounting for the “remarkable difference... when we join belief to the conception, and are perswaded of the truth of what we conceive.” I will argue that this problem, of accounting for assent, arises for Hume precisely because he has abandoned an account of judgment as predication. Furthermore, Hume asserts that the problem is new (“This act of mind has never yet been explain’d by any philosopher”). Again, perhaps it is new because no one before had given an account of judgment that rejected predication, and thus the problem of assent, as Hume sees it, had never before arisen. In this paper, I will explore these themes.
Part Two: Locke and Hume on knowledge and belief
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Locke and Hume on Belief, Judgment and Assent
One fruitful way to understand Hume on these matters is to compare him to Locke. Locke thought that knowledge was the perception of the agreement or disagreement of ideas. But knowledge, Locke thought, was “very short and scanty” (IV.xiv.1)[4]. Fortunately, the “Mind has two Faculties, conversant about Truth and Falshood.” The mind not only has the faculty of knowledge, “whereby it certainly perceives, and is undoubtedly satisfied of the Agreement or Disagreement of any Ideas.” It also has judgment, “which is the putting Ideas together, or separating them from one another in the mind, when their certain Agreement or Disagreement is not perceived, but presumed to be so” (IV.xiv.4). Knowledge is the perception of agreement or disagreement of ideas, while belief, judgment or assent is the presumption or supposition that the ideas agree or disagree. Belief seems to be an approximation to knowledge; where we cannot or do not perceive agreement, we make do with supposing it. In the index to the Essay, added to the second edition, Locke directs us to sections 1 and 3 of Book IV, chapter xv >Of Probability’, for an account of what assent is. He assents to a proposition who “receives it for true.” What “causes his Assent to this Proposition” is “the Probability of the thing”. Just as in the previous section Locke introduced judgment by analogy with knowledge, so here Locke introduces probability by analogy with demonstration:
As Demonstration is the shewing the Agreement, or Disagreement of two Ideas, by the intervention of one or more Proofs, which have a constant, immutable, and visible connexion one with another: so Probability is nothing but the appearance of such an Agreement, or Disagreement, by the intervention of Proofs, whose connexion is not constant and immutable, or at least is not perceived to be so, but is, or appears for the most part to be so, and is enough to induce the Mind to judge the Proposition to be true, or false, rather than the contrary. (IV.xv.1)
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Locke and Hume on Belief, Judgment and Assent
Probability is the appearance of agreement or disagreement of ideas, and it causes our assent. That is, it causes us to presume the ideas to agree or disagree, where we don’t perceive that agreement. Furthermore, Locke makes it clear in this section that judgment is not to be understood by analogy with intuition. We don’t judge two ideas to agree or disagree the way we intuitively perceive their connection; judgment here is compared to the indirect perception that results from demonstrative reason, and it requires proofs or intermediate ideas. There is no immediate belief: belief or assent comes from probable reasoning.[5] These points are repeated in IV.xv.3. “Probaility is likeliness to be true..., signifying such a Proposition, for which there be Arguments or Proofs, to make it pass or be received for true. The entertainment the Mind gives this sort of Propositions, is called Belief, Assent, or Opinion, which is the admitting or receiving any Proposition for true, without certain Knowledge that it is so.” All the ingredients I want to emphasize are here: the comparison with knowledge, the dependence of beliefs on reasoning, arguments and proofs, and the fact that entertaining a proposition is not something we do prior to judging it to be true; entertaining the proposition is judging it to be true. Assent is not a separate act from proposition formation.
Locke sometimes speaks of this judgment as assent.[6] According to Locke, believing or assenting to a proposition, is a sort of pale imitation of knowing it, a presuming rather than a perceiving. Both knowledge and belief involve proposition formation; predication is a form of affirmation or denial. Assent is not an attitude one takes towards a proposition already formed. So when Locke speaks of a self-evident proposition as something one “assents to at first sight” (4.7.2), he is not saying that we believe or assent to something known; he is just saying we come to know it.[7] Hume disagrees with much of this. He doesn’t think of belief as an approximation to, or a pale imitation of, knowledge. He treats belief both as the idea believed and as that feature of the idea that constitutes our assent to it. He allows that we can conceive of a (probable) proposition without affirming or denying it. Furthermore, Hume treats this assent, with respect to beliefs, as something quite distinct from whatever it is that compels our assent to things that we know. Hume’s account of belief is quite distinctive, and this fact helps explain why he thinks of his account as so new and original.
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Locke and Hume on Belief, Judgment and Assent
The crucial points are these. Both Locke and Hume consider judgment to be limited to belief formation, and not to extend to proposition formation in general. Locke thinks that belief is a pale imitation of knowledge, and in both cases the predicative process by which the proposition known or believed is formed just is the process of affirming or denying one idea of another. By and large, Hume accepts this account of knowledge, to the extent that he is interested in it at all. But he rejects any predicative account of belief formation, at least for the central case of beliefs that involve existence. But in rejecting this, the Lockean account of the assent we give to beliefs is no longer available to him.[8]
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Locke and Hume on Belief, Judgment and Assent
It is almost impossible, for us post-Russellians immersed in propositional attitude psychology, to resist distinguishing between forming or understanding a proposition, and judging it to be true. But we must guard against bringing this distinction to Locke: it is a fundamental error in understanding Locke’s account of knowledge and belief. For Locke, to perceive, or judge, that two ideas agree or disagree simply is to know, or believe, the proposition formed by the agreement or disagreement of ideas. And to know, or believe, such a proposition is to know it with certainty, or believe or assent to it with relevant degree of assurance. Predication isn’t distinct from affirmation or denial; understanding propositional content isn’t distinct from knowing or judging to be true. Propositions just are ideas “put together, or separated by the Mind, perceiving, or judging of their Agreement, or Disagreement.” (IV.v.5)[9] But perceiving or judging the agreement of ideas is to know (or believe) the relevant proposition, to take it as true, and to be aware of the relevant degree of certainty (or assurance). There is only one act of the mind here (perception in the case of knowledge; presumption, supposition or judgment in the case of belief) and only one object (the agreement or disagreement of ideas.) As a result, Locke frequently says such things as the following: “Certainty of Knowledge is, to perceive the agreement or disagreement of Ideas, as expressed in any Proposition. This we usually call knowing, or being certain of the Truth of any Proposition.” (IV.vi.3) To form a proposition, to know, to believe, to assent to, to take as true, to consider certain or probable, all these are just to perceive or presume the agreement or disagreement of ideas.