Episode 51

#51 - Truth, Moose, and Refrigerated Eggplant: Critiquing Chapman's Meta-Rationality


May 29th, 2023

1 hr 12 mins 5 secs

Your Hosts

About this Episode

Vaden comes out swinging against David Chapman's work on meta-rationality. Is Chapman pointing out a fatal flaw, or has Popper solved these problems long ago? Do moose see cups? Does Ben see cups? What the f*** is a cup?

We discuss

  • Chapman's concept of nebulosity
  • Whether this concept is covered by Popper
  • The relationship of nebulosity and the vagueness of language
  • The correspondence theory of truth
  • If the concept of "problem situation" saves us from Chapman's critique
  • Why "conjecture and criticism" isn't everything


Chapman Quotes

Reasonableness is not interested in universality. It aims to get practical work done in specific situations. Precise definitions and absolute truths are rarely necessary or helpful for that. Is this thing an eggplant? Depends on what you are trying to do with it. Is there water in the refrigerator? Well, what do you want it for? What counts as baldness, fruit, red, or water depends on your purposes, and on all sorts of details of the situation. Those details are so numerous and various that they can’t all be taken into account ahead of time to make a general formal theory. Any factor might matter in some situation. On the other hand, nearly all are irrelevant in any specific situation, so determining whether the water in an eggplant counts, or if Alain is bald, is usually easy.

Do cow hairs that have come out of the follicle but that are stuck to the cow by friction, sweat, or blood count as part of the cow? How about ones that are on the verge of falling out, but are stuck in the follicle by only the weakest of bonds? The reasonable answer is “Dude! It doesn’t matter!”

We use words as tools to get things done; and to get things done, we improvise, making use of whatever materials are ready to hand. If you want to whack a piece of sheet metal to bend it, and don’t know or care what the “right” tool is (if there even is one), you might take a quick look around the garage, grab a large screwdriver at the “wrong” end, and hit the target with its hard rubber handle. A hand tool may have one or two standard uses; some less common but pretty obvious ones; and unusual, creative ones. But these are not clearly distinct categories of usage.

Popper Quotes

Observation is always selective. It needs a chosen object, a definite task, an interest, a point of view, a problem. And its description presupposes a descriptive language, with property words; it presupposes similarity and classification, which in their turn presuppose interests, points of view, and problems. ‘A hungry animal’, writes Katz, ‘divides the environment into edible and inedible things. An animal in flight sees roads to escape and hiding places . . . Generally speaking, objects change . . . according to the needs of the animal.’ We may add that objects can be classified, and can become similar or dissimilar, only in this way—by being related to needs and interests. This rule applies not only to animals but also to scientists. For the animal a point of view is provided by its needs, the task of the moment, and its expectations; for the scientist by his theoretical interests, the special problem under investigation, his conjectures and anticipations, and the theories which he accepts as a kind of background: his frame of reference, his "horizon of expectations".

  • Conjectures and Refutations p. 61 (italics added)

I believe that there is a limited analogy between this situation and the way we ‘use our terms’ in science. The analogy can be described in this way. In a branch of mathematics in which we operate with signs defined by implicit definition, the fact that these signs have no ‘definite meaning’ does not affect our operating with them, or the precision of our theories. Why is that so? Because we do not overburden the signs. We do not attach a ‘meaning’ to them, beyond that shadow of a meaning that is warranted by our implicit definitions. (And if we attach to them an intuitive meaning, then we are careful to treat this as a private auxiliary device, which must not interfere with the theory.) In this way, we try to keep, as it were, within the ‘penumbra of vagueness’ or of ambiguity, and to avoid touching the problem of the precise limits of this penumbra or range; and it turns out that we can achieve a great deal without discussing the meaning of these signs; for nothing depends on their meaning. In a similar way, I believe, we can operate with these terms whose meaning wehave learned ‘operationally’. We use them, as it were, so that nothing depends upon their meaning, or as little as possible. Our ‘operational definitions’ have the advantage of helping us to shift the problem into a field in which nothing or little depends on words. Clear speaking is speaking in such a way that words do not matter.

  • OSE p. 841 (italics in original)

Frege’s opinion is different; for he writes: “A definition of a concept ... must determine unambiguously of any object whether or not it falls under the concept . . . Using a metaphor, we may say: the concept must have a sharp boundary.” But it is clear that for this kind of absolute precision to be demanded of a defined concept, it must first be demanded of the defining concepts, and ultimately of our undefined, or primitive, terms. Yet this is impossible. For either our undefined or primitive terms have a traditional meaning (which is never very precise) or they are introduced by so-called “implicit definitions”—that is, through the way they are used in the context of a theory. This last way of introducing them—if they have to be “introduced”—seems to be the best. But it makes the meaning of the concepts depend on that of the theory, and most theories can be interpreted in more than one way. As a result, implicity defined concepts, and thus all concepts which are defined explicitly with their help, become not merely “vague” but systematically ambiguous. And the various systematically ambiguous interpretations (such as the points and straight lines of projective geometry) may be completely distinct.

  • Unending Quest, p. 27 (italics added)

What I do suggest is that it is always undesirable to make an effort to increase precision for its own sake—especially linguistic precision—since this usually leads to loss of clarity, and to a waste of time and effort on preliminaries which often turn out to be useless, because they are bypassed by the real advance of the subject: one should never try to be more precise than the problem situation demands. ... One further result is, quite simply, the realization that the quest for precision, in words or concepts or meanings, is a wild-goose chase. There simply is no such thing as a precise concept (say, in Frege’s sense), though concepts like “price of this kettle” and “thirty pence” are usually precise enough for the problem context in which they are used.

  • Unending Quest, p. 22 (italics in original)

Contact us

How nebulous is your eggplant? Tell us at incrementspodcast@gmail.com.

Support Increments