Thursday, June 19, 2008

Consensus, truth and reality

Stephen Law offers a concise and clear summary of C. S. Pierce's consensus theory of truth, and explores some of the philosophical issues that follow from this definition.

Defining "truth" is a notoriously difficult task, because philosophers typically place the definition at a fundamental metaphysical level, before we have defined notions such as "reality" or "correspondence". To tightly couple truth and reality, then, philosophers typically raise notions of reality to the metaphysical level, i.e. metaphysical realism.

According to Law, Pierce defines truth as "what those who investigate a matter will all eventually agree on." Truth is, in (presumably) Pierce's own words, "The opinion which is fated to by all who investigate is what we mean by truth and the object represented by this opinion is the real."

The typical counterexamples to the consensus theory of truth do not seem to directly rebut Pierce's notion. The most common counterexample is the observation that at one time everyone believed the Earth was flat; despite this consensus, they were all mistaken: the Earth is more-or-less spherical. Law offers his own counterexample:

The suggestion that truth is, at root, whatever we agree it to be might seem open to a very obvious sort of counter-example. Suppose I manage to convince both myself and others that Earth is ruled by Lizard-people from outer space. If the truth is what ever we end up agreeing it to be, then it is true that the Earth is ruled by lizard people from outer space. But of course, this is ridiculous – we can’t just make a claim true by collectively agreeing to it, can we?

These sorts of counterexamples, however, trade on the fact that not everyone agrees to the specified premise. We ourselves do not believe that the Earth is flat, nor do we believe that the Earth is ruled by Lizard-people from outer space. Since there is in fact no consensus, we cannot conclude that these propositions are true by virtue of any consensus. Furthermore, it might be the case that we ourselves are mistaken: The Earth really is flat; Lizard-people do indeed rule the world. Anyone who has swallowed Quantum Mechanics can easily be persuaded that it's possible that a common-sense opinion, which seems blatantly obvious, can actually be mistaken at a fundamental level.

Furthermore, it seems reasonable to take Pierce at his word: The opinion which is fated to by all who investigate, not the opinion which some people, even a large number of people, happen to believe. To do the philosophical job, a counterexample along these lines would have to assert the falsity of an opinion to which everyone believes, including the writer and the readers. This bar seems impossibly high. We cannot tell the difference between a proposition that everyone believes, ourselves included, and a proposition that everyone believes because it's true.

We can, however, critique Pierce's definition on technical grounds. Specifically, the qualifiers "fated to" and those who "investigate" seem vague. How do we tell which beliefs are "fated" and which are mistaken? And what precisely does Pierce mean by "investigate"? Even if we charitably presume he means scientifically investigate, he seems to be begging the question: Why should we privilege scientific investigation a priori? Worse yet, it's not an analytic property of scientific investigation that all investigators are in fact fated to come to the same conclusion.

Pierce's definition fails on pragmatic grounds: It does not do the job we typically expect definitions to do. It is not ostensive (we can point to a chair and say "chair"), it's not operational (length is what we measure with a ruler), and it's not analytic (a bachelor is an unmarried man).

As a concept, however, the coupling between consensus and truth seems appealing. If we look at this coupling in an evidentiary sense, the difficulties with Pierce's use of the concept as a definition evaporate.

We are always surprised, in a deep philosophical sense, by consensus. (In the purely phenomenological sense, we are philosophically surprised when our subjective experiences correlate in unexpected ways.) If people were independently making up arbitrary beliefs, we would expect a range of opinion, not a consensus. All consensus -- indeed any agreement between sufficiently large numbers of people -- calls for some sort of explanation.

Therefore we can modify Pierce's definition to remove the problems: Truth is not what we agree on, truth is what causes agreement. Any time we see agreement, there is some sort of truth causing that agreement. This construction allows us to more flexibility in determining specifically what sort of truth underlies agreement.

In Pierce's construction, we say "if everyone agrees that p, then p is true." Too facile. In the modified construction, we can say, "If everyone agrees that p, then some proposition q is true, and q implies that everyone agrees that p." If q also implies that p, then of course p is true as well.

Looking at the evidence of our daily life, we can discern three primary mechanisms which cause people to widely agree on some proposition: reality: a lot of people agree that the Earth is round because the Earth really is round; deduction: a lot of mathematicians agree that 2+2=4 is a theorem of arithmetic because it's deducible from the axioms of arithmetic; and social construction: a lot of Christians agree that Jesus is the son of God because they have been told so and believed it.

In the first two cases, it's easy to see that what causes the belief to be shared also implies the truth of the belief itself; in the third case (social construction) we can determine the truth of what causes the agreement, but the truth of the cause of the agreement does not imply the truth of what is agreed-upon.

Thus in Law's counterexample, if everyone agreed that Lizard-people from outer space rule the Earth, then there should be some cause of that agreement: it's true by definition that something or other causes the agreement, but that cause may or may not imply that Lizard-people from outer space really do rule the Earth.


  1. I also had trouble with the vagueness of Pierce's definition of truth: "The opinion which is fated to by all who investigate is what we mean by truth and the object represented by this opinion is the real."

    What if the investigators are a minority of the population, as scientists are now? That's a consensus of experts, not the "everyone" that some were talking about on Law's blog. And if we're talking about a consensus, whether of a small group of experts or the population at large, "everyone" doesn't sound like a consensus; that's a unanimity.

    I admit I'm predisposed to accepting the scientific paradigm of contingent knowledge, so I'm strongly agnostic about any "final truths" that may be available to human beings at any time in the future. That aspect of implied perfection in Pierce's truth seems Platonic to me. I just don't see how we can ever know when we're all done with shadow puppets, and have really gotten out of the cave this time.

    BTW, excellent explanation in your post on how consensus implies some truth, though not necessarily that of the object of said consensus.

  2. Would it be fair to suggest that perhaps truth, (as it is happened upon through discovery and invention) is not a revelation regarding the function of the world in itself, but perhaps the revelation of universal human experience as it relates to it?

    The fact that the earth was thought to be flat is an expression of universal experience of a particular phenomenon(which can be said to be true in this case). In other words, truth does not relate to reality (where reality is things in themselves), it relates to experience.

    We might find that Mr. E's physics are wrong some day, but that doesn't invalidate our experience of what he said. It wouldn't invalidate what Einstein said when he stated, "put your finger on a hot stove for a minute, and it feels like an hour. Sit with that special someone for an hour and it feels like a minute. Thats relativity."

    Our experience need not necessarily reflect what's true about the world, only what's true about us.

  3. Would it be fair to suggest that perhaps truth, (as it is happened upon through discovery and invention) is not a revelation regarding the function of the world in itself, but perhaps the revelation of universal human experience as it relates to it?

    Could be; that's not a bad idea. But how can we tell the difference at a fundamental level?

    At any given time, we know only what we think is truly universal. We believe (for good reasons) that our ancestors, were they in the same circumstances, would have the same experiences that we do, and they would draw the same conclusions. Their seemingly valid scientific conclusions are overturned not by virtue of having different experiences, but by virtue of our having more experiences.

    But whose to say that in the future that our descendants will not have even more experiences, which will overturn our own seemingly valid conclusions.

    All we can do is look at some universal experience, and posit some cause for that consensus. In many cases, we cannot explain the consensus by virtue of pure social construction: no one has told you or anyone else the color of this apple, and yet most of us will agree what it is.

    The simplest way to explain such agreement is by hypothesizing that there is some reality "out there", outside our minds, which impinges on all (or most) minds in a consistent manner.

  4. I think part of the problem is in assuming that our conclusions are valid and somewhat atemporal, as apposed to something that simply works for now.

    But I'm somewhat of a pragmatist, so my approach is biased in that regard.

    Regardless of the reality that's out there/that might be out there, it can't be known outside the construction of our own minds. So the beliefe that there is a world out there can be stretched to a beliefe in God.

  5. Regardless of the reality that's out there/that might be out there, it can't be known outside the construction of our own minds. So the beliefe that there is a world out there can be stretched to a beliefe in God.

    Your conclusion does not follow from your premise.

    That all our knowledge is mental is uncontroversial: We know things with our minds. But just because we know things with our minds does not by itself mean that we can't know about things outside our minds.

    To conclude that belief about an external, objective reality can be stretched to belief about God entails that there is no substantive, essential difference between the justification between the two sorts of belief. And to say that there is no essential difference is to say that relative complexity is not an essential part of specifically epistemic belief.

    It's really important to understand that while we take belief in objective, external reality for granted, simply taking a belief for granted does not entail that the belief is specifically metaphysical. Belief in objective reality is justifiable using the scientific method applied only to the facts of our own purely subjective beliefs while remaining metaphysically agnostic about objective reality.

    It's doubly important to note that beliefs about God cannot be justified using the same methodology.

    One is, of course, metaphysically "free" in some sense to refuse to consider relative complexity as essential to epistemology. However, this approach makes it difficult to distinguish between the infinity of possible explanations that form our epistemic candidates.

    Even theists typically adhere to Occam's razor, albeit implicitly and perhaps subconsciously; I've yet to find anyone who pushes the rejection of Occam's razor to its logical conclusion.

  6. "Your conclusion does not follow from your premise."

    I suppose your right.

    All I'm suggesting is that our knowledge of the world is relative to our sensations of it. And, that our sensations (in this case) do not necessarily mirror the world as it is. I'm simply following Kant here.

    Considering a hammer as an outside reality is useful to a cause, and so is considering God as an outside reality. My point here doesn’t necessitate that both objects in question exist in objective reality and that they can be proven on sight. What matters is that they are both, before they are anything, concepts for approaching a particularly human issue.
    - Belief in a reality out there is useful at best, but not right necessarily.

    Occam's razor? I'm not convinced there is a simple answer. But touché.

    I’m not defending belief in God. I don’t believe in God and as a matter of fact, I don’t really know what I believe.


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