1 2-8 基礎付け主義を超えて Upon what are our beliefs about causal

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2-8
基礎付け主義を超えて
Upon what are our beliefs about causal connections based? Two possibilities have generally been
acknowledged: reason and experience. Hume rejected the possibility of reason. Suppose I believe that the
moving cue ball will cause the eight ball to move upon impact. Still I can conceive that the motion of the
cue ball stops and the eight ball does not move in the slightest. My conception does not depend on their
being anything unusual about the situation. The belief is not based simply on the existence of the constant
conjunction between the two. It is also based on the expectation that the patterns previously to repeat
themselves will continue to repeat themselves. Everything is based on a belief that nature is uniform with
respect to repetition. Since we can conceive of the end of the uniformity of nature, reason is of no help. So
we could only appeal to experience: nature has always proved to be uniform. But why do we believe that
the pattern of repetition of patterns will repeat itself? Our experience cannot justify this belief. The basis
of probability can be understood as degree of belief based on observed frequencies. For Hume the concept
of probability is not enough to treat irregularities, for we can imagine pure chance, full randomness．
There is no impression of a necessary connection. Even if we observe any two physical events, we will
find only a succession. In Treatise (I, III, XIV), he says, “ Either we have no idea of necessity, or
necessity is nothing but that determination of the thought to pass from causes to effects and from effects
to causes, according to their experienced union.”
Hume’ s problem
3 predictions and generalizations
2 present and past observations
Descartes’ problem
1 indubitable beliefs
The sun will rise tomorrow.
The sun is now rising.
The sun has risen each day that I
have made an observation
I now seem to see a sunrise.
I now seem to remember that the
sun has risen each day that I have
made an observation.
Hume も Descartes も基礎付け主義者である。その理由は、二人とも、もし信念が合理的に正当
化される(知られる)なら、それはより低いレベルの事柄への関係に基づいてだけ正当化される
(知られる)、と考えたからである。
(上の表の１、２、３が各レベルを表わしている)
Hume：レベル３の信念が正当化されるのであれば、それはレベル２の事柄だけを基礎にして正
当化されなければならない。
Descartes：レベル２の信念が正当化されるのであれば、それはレベル１の事柄だけを基礎にし
て正当化されなければならない。
共に If-statement であることに注目すべきである。彼らは問題になっている信念が実際に正当化
されると主張しているのではない。正当化のために何が真でなければならないかを主張してい
るのである。
Descartes と Hume の結論はまったく正反対である。Descartes はレベル１に基づいてレベル２の
信念は正当化できると考えたが、Hume はレベル３の信念はレベル２からは正当化できないと結
論した。
各レベルを結びつけるもの(connecting principle)：神の存在と神は欺かないこと(Descartes)、自然
の一様性原理(Hume)
もし合理的な正当化が演繹的になされるのであれば、Hume の懐疑主義は正しく、Descartes は
誤っている。
(主張)低いレベルの言明は高いレベルの言明の正当化には不十分である。
2
（１）今あなたの前には黒板が見えるようである。
（２）今あなたの前には黒板がある。
（１）から（２）が導き出せるかどうかは、あなたがどのような想定のもとに（１）を考える
かにある。（１）だけから演繹的に（２）を導き出すことは不可能である。
relative to the background assumptions
このような背景とする知識や信念なしには基礎付け主義は懐疑論に陥る。
懐疑論の系譜
１ Bacon の帰納的方法：Novum Organum, 1620
科学の目的：現象的な規則性の単なる一般化ではなく、その現象的な規則性の背後にある原因
を発見すること (彼はアリストテレスの形相(form)を原因の意味で使った)
個々の場合の観察 ⇒ それに関する適切な推理 ⇒ 原因の発見
(例) 熱の原因
熱の肯定的な例、熱の否定的な例、熱の程度
Each property in the conjunction occurs in every positive instance,
in every negative instance, some property in the conjunction is absent,
the conjunction of properties increases in intensity as the phenomenon increases in intensity.
Bacon の方法は１７世紀後半には新しい科学の規範となった。J. S. Mill の A System of Logic での
帰納法の扱いは Bacon とまったく同じである。
２ Newtonian Revolution
Philosophiae Naturalis Principia Mathematica (Mathematical Principle of Natural Philosophy) 1686
４部からなる。
１部：目的、定義と公理
２部：(book 1) さまざまな数学的形式の力に従う物体の運動に関する定理、それらの導出は
Euclid の Elements と同じ形式をとる。
３部：(book 2) 流体の中での物体の運動と波の運動
４部：(book 3) 万有引力の法則と天体の運動の観測結果の組み合わせ
In Newton’ s conception, what we see and observe are apparent motions. The effects we see in nature are
effects compounded of several different causes or forces. He thought that besides apparent motions there
are real motions, that is, motions with respect to absolute space.
the rotating-bucket experiment
The point of the Principia is to show how to infer true motions and causes from apparent motions and
causes.
慣性の法則、運動量保存の法則、作用反作用の法則（Euclid の公理に対応）
(the argument for the law of universal gravitation)
He started with observed regularities about the motions of the sun, moon, and planets and the properties
of pendula on the earth. Using these regularities and logical consequences of his three laws as premises,
he deduced that there exists a force attracting the planets to the sun, a force attracting the satellites of
Jupiter to the planet Jupiter, and a force attracting the moon to the earth. He proved from these premises
that the force in question varies inversely as the square of the distance between the bodies and that the
force is proportional to the products of the masses of the bodies. From generalizations induced from
observed regularities and from his three laws of motion, he deduced that there exist bodies in which one
body attracts the other with a force given by the equation F = GMM’/r2. He then inferred inductively that
for every pair of particles in the universe, there is such a force between them. (general induction from the
phenomena)
Newton’ s argument for universal gravitation and the general achievement of the Principia formed the framework for
much of science in the 18th and even the 19th centuries. Later physicists sought to establish the existence of other
forces and their laws through arguments that paralleled Newton’ s, while philosophers of science believed that they
saw in Newton’ s arguments the most penetrating insights into the structure of nature.

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