阿奎那科學探討中的「量」與「質」

除了實體的存在之外，附體（accidentia）的存在結構特別是其中的量（quantitas）與質（qualitas）亦與阿奎那的科學分類密切相關。而關於附體的探討就涉及阿奎那的十範疇（categoriae）學說，其十範疇學說本諸亞里士多德，阿奎那則在存在的基礎上統貫十範疇^[1]，說明了十範疇即為存在的十種不同樣態（diverus modus essendi）^[2]。阿奎那探討十範疇的主要文本在《形上學註》與《物理學註》中，兩處雖對實體以外附體九範疇解釋次序略有不同，但是兩處都同意「量」與「質」的幾個特點：一、兩者不是實體本身（，所以是附體）；二、兩者都存在於實體之內^[3]（，除了「關係」其他都實現於實體之外）；三、兩者都是賦謂實體^[4]（，其他附體都與實體和外境的互動相關）。針對存在者的質與量，《波三探微》也作出解釋。量是基於悟性質料（materia intelligibilis）^[5]而為存在者能夠個體化為一個一個彼此區別的因素^[6]，具體而言，量這個附體就是數目與形狀（fugura）^[7]。而質是基於可感質料（materia sensibilis）^[8]而使存在者具備可謂感官所認知的可感特性的因素，具體而言，就像一個人所具有的骨（os）與肉（carnis）。實體、量與質在存在的次序上，是實體為先、量次之而質與變易（motus）最後^[9]，因為沒有量的前提，質也無法成立^[10]；而沒有實體，所有附體都無法成立。這樣，量與質固然不是實體本身，也不是本質本身，但是卻是實體落實為個別存在者不可或缺的因素，因而成為科學認知中無法缺乏的環節。

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  ^[1]       十範疇：實體（substantia）、量（qunatitas）、質（qualitas）、關係（relatio）、裝備（habitus）、時間（quando）、空間（ubi）、主動（actio）、被動（paasio）、姿態（situs）。

  ^[2]       John F. Wippel, The Metaphysical Thoughts of Thomas Aquinas (Washington: The Catholic University of American Press, 2000), p.215-216. “According to the Critique of Pure Reason (A81/B106-107), Aristotle relied on sheer induction in arriving at his haphazard list. He did not develope it systematically from any common principle. Whatever the merits of this criticism when leveled against Aristotle, it does not seem to apply fully to Aquinas. As he sees things, these is a kind of principle to account for the fact that there are ten and only ten categories or predicaments. ... different modes of being.”

  ^[3]       In V. Meta., n. 892: “Secundo modo ut praedicatum sumatur secundum quod inest subiecto: quod quidem praedicatum, vel inest ei per se et absolute, ut consequens materiam, et sic est quantitas: vel ut consequens formam, et sic est qualitas…”

  ^[4]       In III Physics., n.322: “Alius autem modus est quo praedicatur de aliquo id quod non est de essentia eius, tamen inhaeret ei…hoc est praedicamentum quantitatis…sic est praedicamentum qualitatis….”

  ^[5]       SBDT q.5, a.3, responsio. “Et sic secundum rationem suae substantiae non dependet quantitias a materia subsibili, sed solum a materia intelligibili.”阿奎那進一步解釋所謂悟性「質料」，稱為質料不是說他本身是種物質，而是它的存在必須在物質裡被發現。Ibid., q.5, a.3, ad2. “dicendum quod materiale dicitur non solum id, cuius pars est materia, sed etiam illud, quod in materia esse habet…”

  ^[6]       Ibid., q.5, a.3, ad3. “Materia autem dividi non potest nisi ex praesupposita quantitate, qua remota omnis substantia indivisibilis remanet…”

  ^[7]       Ibid., q.5, a.3, responsio. “Sed intelligitur de forma accidentali, quae est quantitas et figura, a qua quidem materia sensibilis per intellectum abstrahi non potest…”

  ^[8]       Ibid., q.5, a.3, responsio. “Unde quantitas potest intelligi in materia subiecta, antequam intelligantur in ea qualitates sensibiles, a quibus dicitur materia sensibilis.”

  ^[9]       Ibid., q.5, a.3, responsio. “Sed accidentia superveniunt substantiae quodam ordine. Nam primo advenit ei quantitas, deinde qualitas, deinde passiones et motus.”

^[10]       Ibid., q.5, a.3, responsio. “…cum qualitates sensibiles non possint intelligi non praeintellecta quantitate, sicut patet in superficie et colore, nec etiam potest intelligi esse subiectum motus, quod non intelligitur quantum.”