[This is a continuation of a thread begun here.]
Another example of fetishizing the visible (cf. now also this) occurs in Karl Popper’s Conjectures and Refutations: the Growth of Scientific Knowledge (1962; page refs. to the Harper paperback reprint), p. 284:
In the last pages of Testability, Carnap discussed the sentence ‘If all minds should disappear from the universe, the stars would still go on in their courses.’ Lewis and Schlick asserted, correctly, that this sentence was not verifiable.
They so asserted incorrectly. After all, we have a pretty good handle on those stars in their courses, beginning from not long after the Big Bang through the present, during most of which there were no human minds.
And here’s a simpler experiment: Let’s all just refrain from observing the moon for the next two weeks. Now we open our eyes. Surpri-ise! Right where we expected to find it, and at a phase two weeks more mature than when we last checked (rather than the phase as last seen).
One occasionally observes a very young child shut her eyes and announce in a sing-song: “Youuu ca-han’t seee mee….!” I doubt the child actually believes that, it’s just fun to say. But suppose she did. She is then entertaining an erroneous optical theory, but not an erroneous ontological one. She imagines that the lights went out for you as well; but she never entertains the thought that you yourself have been extinguished, or been transfixed into some mute deaf motionless limbo until such time as she shall be pleased to gaze again – after all, she has just shown this, by addressing you.
Incidentally, the whole Schlick-shop with its merry/morose band of logical positivists, appear to have created enormous problems for themselves, and come up with completely counter-intuitive results, from the basic motivation of wishing to exclude all metaphysical propositions from the outset as strictly meaningless. (The story here is in line with our overarching defense of theism.) In other words, it wasn’t enough to denounce as wholly unconvincing, all purported metaphysical statements hitherto; nor to brand it a particularly uninteresting language-game; nor to marginalize the enterprise with the derision usually reserved for circle-squarers. Metaphysics as such, and for all time, had to have a stake driven through its heart, the stake itself consisting in pure reasoning from selbstverständlich (metaphysically a-priori? God-given? -- oops, NOT) first principles. For a demonstration of the absurdities that apparently resulted, cf. Popper, passim. As (p. 281, op.cit.)
My criticism of the verifiability criterion has always been this: against the intention of its defenders, it did not exclude obvious metaphysical statements, but it did exclude the most important … of all scientific statements … the universal laws of nature.
Why even go near such a disaster, for the sake of excluding-in-principle all metaphysical statements – which they were ignoring anyway? Popper goes so far as to hazard a guess in a footnote to p. 175: “One not need believe in the ‘scientific’ character of psycho-analysis (which, I think, is in a metaphysical phase) in order to diagnose the anti-metaphysical fervour of positivism as a form of Father-killing.” (Note, b.t.w., the capital initial of “Father”.)
Since we were obliged, a moment ago, to deprecate Popper, let us hasten to another example, in which we find him on the side of the angels. First let us note:
* Our conduct is guided by moral laws.
* Our scientific activity is guided by metaphysical principles.
* Both categories are philosophically vexed, and any concrete application of these laws and principles may prove problematic; but we cannot do without them.
Here is Popper (p. 287) characterizing the logical positivists: “They implicitly accept the rule: ‘Always chose the most probable hypothesis!’ He goes on:
Now it can be easily shown that this rule is equivalent to…’Always choose the hypothesis which goes as little beyond the evidence as possible!’ And this, in turn [amounts to] ‘Always choose the hypothesis which has the highest degree of ad hoc character!’
an undesirable result for science. (Cf. Chomsky, passim, re the extraordinarily abstract and roundabout way you may have to proceed to get valid results, by no means simply tip-toeing a bit beyond “the evidence”.)
The principles which we require instead may be best illustrated by an old joke (presented here in a slightly revised form):
A zoologist, a mathematician, and a positivist are touring the hinterlands of Bohemia by train. Through the window they spot, standing motionless at some distance, a purple cow.
“Fancy that!” exclaims the zoologist. “There are purple cows in Bohemia.”
The mathematician, in a low voice, amends: “There is at least one purple cow in Bohemia.”
The positivist, raising his finger, crisply corrects to: “In Bohemia there is at least one cow, purple on one side.”
The joke is that the positivist has the most precise view of the evidence; and of the three statements, only his own is certainly true (interpreting an unmodified “purple cow” in the natural way, as “purple more or less all over”); yet his scruples are absurd. Science would not progress, were it bound by such fragmented literalism. (Indeed, we should have to replace “cow” with “an apparently bovine organism”, and always assuming that we can rule out a mirage, or a collective hallucination, or some effect of swamp gas; or for that matter an analogue to one of Hilary Putnam’s pet entities, the Mechanical Cat from Mars.) And we would have to gloss Quine’s celebrated interjection, gavagai!, as possibly: “Lo, a rabbit-stage, seen from the east.”
(For more on bovine mathematics, see "How Now, Round Cow".)
Note: Occasionally one meets with such unilateral positivist agnosticism in a non-jocular context:
Franz Ferdinand rode erect, his visible foot deep in the stirrup, a saber at his side.
-- Robert D. Kaplan, Balkan Ghosts (1993), p. xxvi
To move from this to an outlook useful for science, we need these metaphysical principles:
(1) a certain uniformity or self-cohesion to nature
(2) the reliability (not in a logical, but in a practical sense) of induction.
(There are others, of course, such as the usefulness of deduction; but that applies in every world, not just in this contingent one.)
Now, both these principles are of vexed and delicate application; as are, indeed, the Commandments. Just as it is difficult to avoid situation ethics, I see no way around a kind of “situation metaphysics”. The zoologist, using these principles, together with his discipline-specific knowledge (to the effect that animals generally come in species, not as singletons), concludes the presence of purple cows. But here I must side with the formulation of the mathematician: there is at least one such cow, but perhaps no more. For, nature’s uniformity depends on the domain. Were an experiment ever to identify, say, a Higgs boson, we should conclude the existence of an emphatic plurality of Higgs bosons; that there should only be one in the universe, is inconceivable. But biology is more mottled than that. Given our collective prior acquaintance with hundreds of thousands of cows, none of which was ever purple, we would hypothesize here an extremely rare mutation for (bilateral) purple (bilateral because bilaterally symmetric animals generally continue to evolve with bilateral symmetry, pace the occasional narwhal). Since a cow delivers but a single calf at a time, this one has no identical siblings, so it is probably unique. Moreover, the bulls will likely shun her for her color, and she shall have no offspring. The mutation dies with her.
Carnap attempts to avoid the assumption of a metaphysical principle, by declaring (1) to be “analytic” (i.e., more like “2+2 = 4” than like “animals tend to come in species” or “each elementary particle is invariable within its class”). Popper comments (p.289) that “no such principle of uniformity can be analytic (except in a Pickwickian sense of ‘analytic’)." In fact, we noticed, the principle is nothing remotely like analytic, having always constraints on its application, which in some domains may be severe. And as for (2), I concur with Popper (p.292) that it is “a principle of a priori metaphysics.” And none the worse for that.
[For further notes on ineluctable metaphysical underpinnings of the scientific enterprise, see here.]