【メモ】 F. A. Hayek, "Degrees of Explanation"

以下個人用メモ。ページ番号はStudies in Philosophy, Politics, and Economics (1967)のもの。

"It ['explanation of the principle'] is a theory which neither aims at specific prediction of particular events, nor is based on hypotheses in the sense that the several statements from which it starts are expected to be confirmed or refuted by observation. Although, as is true of any scientific theory, it does delimit a range of facts which are permitted by it against others which it 'forbids', our purpose in examining the facts is not to ascertain whether the different individual premisses from which the theory starts are true, but to test whether the particular combination of undoubted premisses is adequate to arrange the known facts in a meaningful order, and (what in a sense is the same thing) to show why only certain kinds of events are to be expected while others are precluded.
However we prefer to phrase the individual premisses from which we deduce the theory of evolution, they will all be of such a kind that we do not doubt their truth and should not regard them as refuted if the conclusions drawn from them jointly should be contradicted by observation."(p.12)

ハイエクの「原理の説明」の考え方が簡潔に述べられた箇所。明確に反ポパー的。

"Where only the most general patterns can be observed in a considerable number of instances, the endeavor to become more 'scientific' by further narrowing down our formulae may well be a waste of effort; to strive for this in some subjects such as economics has often led to the illegitimate assumption of constants where in fact we have no right to assume the factors in question to be constant."(p.16)

ここもポパーの機械的な反証主義に対する批判として読める。

"An explanation of the principle will thus often enable us to create such favourable circumstances even if it does not allow us to control the outcome. Such activities in which we are guided by a knowledge merely of the principle of the thing should better be described by the term cultivation than by the familiar term 'control' - cultivation in the sense in which the farmer or gardener cultivates his plants, where he knows and can control only some of the determining circumstances and in which the wise legislator or statesman will probably attempt to cultivate rather than to control the forces of the social process.
But if it is true that in subjects of great complexity we must rely to a large extent on such mere explanations of the principle, we must not overlook some disadvantages connected with this technique. Because such theories are difficult to disprove, the elimination of inferior rival theories will be a slow affair, bound up closely with the argumentative skill and persuasiveness of those who employ them. There can be no crucial experiments which decide between them. There will be opportunities for grave abuses: possibilities for pretentious, over-elaborate theories which no simple test but only the good sense of those equally competent in the field can refute. There will be no safeguards even against sheer quackery.
Constant awareness of these dangers is probably the only effective precaution. But it does not help to hold up against this the example of other sciences where the situation is different. It is not because of a failure to follow better counsel, but because of the refractory nature of certain subjects that these difficulties arise. There is no basis for the contention that they are due to the immaturity of the sciences concerned. It would be a complete misunderstanding of the argument of this essay to think that it deals with a provisional and transitory state of the progress of those sciences which they are bound to overcome sooner or later."(p.19)

庭師の比喩に続いて、「原理の説明」に付随せざるを得ない否定的な帰結について。"pretentious, over-elaborate theories"とか"sheer quackery"と呼ばれているのは、ケインズ派や新古典派の過度に数学的な経済学のことだろう。

最後に：

"It cannot be our task here to inquire whether what we have considered with regard to the disciplines which had, from their very beginning, to deal with relatively complex phenomena, may not also become increasingly true of the discipline which was at least able to start with the relatively simple: that is, whether not even physics, as it ceases to treat of a few connected events as if they were closed systems, and at the same time develops in a manner which makes it necessary to define its terms in relation to each other, and in consequence only the theoretical system as a whole but no longer in part be really falsified, will increasingly have to face the same difficulties with which we are familiar from the biological and social sciences."(p.20)

既に1955年の時点で、いずれ物理学も複雑系（閉じたシステムではなく、諸要素の挙動が相互に依存している系）の分析に進むだろうことを予見していた先見性が凄い。