Skepticism(P.Klein2015) |
First published Sat Dec 8, 2001; substantive revision Tue Jun 2, 2015
(https://plato.stanford.edu/entries/skepticism/#Pyr)
by Peter Klein
の勉強。とくにSection7Pyrrhonism以後。Kleinの無限主義の確認が主な目的。ついでに、彼による問題の整理の確認。
イントロ
懐疑論への対応の仕方で諸認識論を定義できる
懐疑論の制限形と一般形
制限形:we cannot have knowledge of any propositions in some particular domain that is normally thought to be within our ken.
例:the problem of other minds、the problem of induction
一般形:question our knowledge in many, if not all, domains in which we ordinarily think knowledge is possible.
ここでは、一般形を扱う。これは今日の認識論者たちが最もinterestingとみなしているもの。
ターミノロジー(Section2. Two Basic Forms of Philosophical Skepticism)
“EI-type” propositions to refer to epistemically interesting types of propositions.
it would be epistemically interesting if we cannot know anything about the future, or anything about the contents of someone else's mind, or anything about the past, or anything at all about the “external world.”
Three stances; We can
1.Assent that we can have knowledge of EI-type propositions. (“Epistemist”)
2.Assent that we cannot have knowledge of EI-type propositions. (That is, deny that we can have knowledge of EI-type propositions.) ("Academics”, “Cartesian skepticism” , “switched world skepticism” , “possible world skepticism” )
3.Withhold assent to both the proposition that we can have knowledge of EI-type propositions and withhold assent to the proposition that we cannot have such knowledge.
(“Pyrrhonian Skeptics” )
このエッセイの主なターゲットは Academic Skepticism
Although recently there has been a renewed interest in Pyrrhonism, it is fair to say that when contemporary philosophers write or speak about skepticism they usually are referring to some form of Academic Skepticism. Thus, we will now turn to that form of skepticism, and it is that form that will be the primary focus of this essay, although we will consider some aspects of Pyrrhonism later.
とのことだが、本稿が今回興味をもつのはPyrrhonism(「人気」があるのはたしかにAcademic Skepticism(知識に関する懐疑論)だが、私の意見ではより根本的であるのはPyrrhonism)
7. Pyrrhonism
Sextus: Outlines of Pyrrhonism [PH]
The Pyrrhonians thought that there were modes which could induce withholding assent to the results of reasoning. It is to those modes that we now turn.
ピロン主義哲学の文献のなかでおそらく最も影響力の大きかった章
Perhaps the most influential passage in the corpus of the Pyrrhonian literature is a section in a chapter from PH entitled “Five Modes of Agrippa.” Although the chapter title mentions five modes, two of them repeat those found elsewhere and are similar to the ones just discussed concerning perception. They are the modes of discrepancy and relativity and are important because they provide the background for understanding the description of the three modes concerning reasoning. Specifically, it is presumed that the relevant object of inquiry is subject to legitimate dispute and that reasoning is employed to resolve the dispute. The issue before us then is whether reasoning can legitimately lead to assent. Sextus writes:
問題:論証は最終的な同意に導けるか?
セクスタスは次のように書いている。
The Mode based upon regress ad infinitum is that whereby we assert that the thing adduced as a proof of the matter proposed needs a further proof, and this again another, and so on ad infinitum, so that the consequence is suspension [of assent], as we possess no starting-point for our argument … We have the Mode based upon hypothesis when the Dogmatists, being forced to recede ad infinitum, take as their starting-point something which they do not establish but claim to assume as granted simply and without demonstration. The Mode of circular reasoning is the form used when the proof itself which ought to establish the matter of inquiry requires confirmation derived from the matter; in this case, being unable to assume either in order to establish the other, we suspend judgement about both. (PHI:166–169)
問題のポイント:ドグマチストがpを主張している。その理由としてqを挙げている。qの理由としてrを挙げている、・・ピュロン主義者はドグマチズムの陥穽に陥らないためにはどのように振舞えばよいか?
示唆されているやり方:ドグマチストを無限遡行に追い込むか、恣意的な独断に導くか、または、論点先取に追い込む。
The question is this: Supposing that the dogmatist assents to something, say p, on the basis of a reason, say q, and gives r as his reason for q, etc., how should the Pyrrhonian react in order to avoid the snares落とし穴 of dogmatism? The suggestion in this passage appears to be to force the dogmatist into either an apparently never ending regress or an arbitrary assertion or begging the question.
今日それぞれのやり方、「無限主義」、「基礎づけ主義」、「斉合主義」と呼ばれている。
This strategy is apparently based upon the claim that there are (only) three possible patterns which any instance of reasoning can take. Today we call the first pattern “infinitism”; the second “foundationalism”; and the third “coherentism.” I will follow that nomenclature.
これらのやり方の難点―同意に導かないことをピュロン主義者は述べていたことになる。
(1) The Mode to Respond to the Foundationalist 基礎づけ主義者の論法に対するピュロン主義者の反対議論
ピュロン主義者は、その議論は間違っているとは言わない。彼が信じるのは次:基礎づけ主義には非合理が含まれている。それは不可避的に恣意に導くー十分疑える命題に合理的な理由なしに同意するという恣意性である。Arbitrariness seems inevitable.
(2)The Mode to Respond to the Coherentist 斉合主義者の論法に対するピュロン主義者の反対議論
斉合主義には2種類ある
1) the “warrant-transfer form”:円、ぐるぐる回り
Aristotle pointed out thatthis process of reasoning could not resolve matters. As he put it, “ it is easyto prove everything in this way.” (Posterior Analytics, I, iii, 73a5).
2) the“warrant-emergent form” :命題群が蜘蛛の巣のような相互依存関係にある。斉合性をその集合はもち、そのメンバーである個々の命題に一度に保証(warrant)が与えられる(See Quine and Ullian 1978 and Bonjour 1978 for defenses of warrant-emergent coherentism)
難点
無限主義:無限遡行は実は立派な議論
“finite mind objection”:人間の心は有限だから無限遡行は不可能。
This objection, often referred to as the “finite mind objection” was first stated by Aristotle. As he put it, “…one cannot go through infinitely many things in thought.” (Posterior Analytics, I, xxii, 83b6)
(Williams 1981, 85)も同様な異議
無限主義の要点
正当化したい信念があったとしよう。別の信念があって、それが信念を受けいれる理由をあたえる(正当化する)。これが成立するためには、別の信念がそれ自身正当化されている必要は必ずしもない。しかし、理由自身疑われうる。それを受けいれる別の理由が提示される。このプロセスは原則として限りがない。このプロセスでおきるのは理由の増強(reason-enhancement)である。理由の鎖が長くなるにつれて、目標とする信念の理由増強は増加する。
どのような理由も正当に疑われうる、だから潜在的な理由の鎖は限りがない。
決定的なポイント:人間の心は有限だから、理由の無限集合を提出する必要はない。理由の鎖が長くなるにつれて、目標とする信念の理由増強は増加する。よって、ある場合には、理由の無限鎖の中の有限集合を利用すれば、知識のために求められる正当化の敷居に届くのに十分となる。
As the chain of reasons lengthens, the target belief's reason-enhancement increases.
無限主義は比較的最近の立場、認識論における少数派。遡行問題に対する有力な応答として、基礎づけ主義や斉合主義、ピュロン主義的懐疑論に加わるかどうかは今後を見ないとわからない。
(See Aikin 2010, and Klein 1999, 2007 for defenses of infinitism; and see Turri and Klein 2014, Aikin and Peijnenburg 2014, and Peijnenburg and Wenmackers 2014 for collections of essays which defend or criticize various forms of infinitism.)
まとめ
The Overall Effect of the Modes
IF there are only three patterns of reasoning available to settle matters, and IF none of them can settle matters sufficiently to warrant assent, and IF assent is required for knowledge, it seems that the Pyrrhonian has a viable strategy for resisting dogmatism because no process of reasoning could lead to knowledge of non-evident propositions. But those are big “IFs,” and each has been challenged.
(工事中)