Between physics and metaphysics: Mulla Sadra on nature and motion

Islam & Science, June, 2003 by Ibrahim Kalin

After these considerations, Sadra introduces an axiological element into the discussion, which, in turn, confirms the ontological discrepancy that Sadra establishes between potentiality and actuality on the one hand, and existence and non-existence, on the other.

   Goodness (al-khayr) in things comes from the fact that
   they are actual whereas evil (al-sharr) stems from what
   is potential. A thing cannot be evil in every respect
   otherwise it would be non-existent. And no being, in so
   far as it is something existent, is evil. It becomes evil as
   a privation of perfection such as ignorance, or it
   necessitates its own non-existence in other things such
   as injustice (al-zulm).

   Since potentiality has some sort of actualization in the
   external world, its essence subsists by existence. And
   existence, as you have seen, is prior to essence in an

   absolute way. Therefore, potentiality as potentiality has
   external realization only in the mind. Thus, it is
   concluded that whatever is actual is prior to the
   potential in terms of causation (bi'l-cilliyyah), nature
   (bi'l- tab'), perfection (bi'l-sharaf), time, and actual
   reality (bi'l-haqiqah). (29)

Nature as the Immediate Cause of Motion

As we have stated previously, motion is the act of moving itself (mutaharrikiyyat al-shay') for it refers to the continuous renewal and lapse of the moving body in a particular time-space coordinate. This point is of extreme importance for Sadra's purposes here for he tries to establish motion as an essential property of corporeal bodies, and this is a major step towards substantial motion (al-harakat al-jawhariyyah) as opposed to positional or locomotive motion. In this sense, the immediate cause of motion should be something whose essence is not stable. Otherwise 'a stable or enduring entity will contain in itself the passing phases of motion as a present fact, and this togetherness of all passing phases would amount to stability, not motion.' (30) This leads Sadra to the following conclusion: The immediate cause of every motion should be something whose quiddity (mahiyyah) is stable but whose being (wujud) is ever-changing.

   The immediate cause of motion has to be something
   with a stable essence and continuously changing being
   (thabitat al-mahiyyah mutajaddid al-wujud). As you will
   see, the immediate cause of all kinds of motion is no
   other than nature. This nature is the substance by
   which things subsist and become actualized as a species
   (i.e., as a particular entity) (31). This refers to the first
   perfection of natural things in so far as they are actual
   beings (in the external world). Therefore it is
   concluded and established from this (consideration)
   that every physical being is a continuously changing
   entity with a flowing identity (sayyal al-huwiyyah) despite
   the fact that its quiddity is impervious to change. (32)

The statement that the subject of motion should be something with a stable essence is true only when we mean by 'stable' (thabit) the quiddity (mahiyyah), viz., the mental image of things. Or, we understand from 'stable' the subject of motion, which is not a concomitant (lazim) for the actual existence of the thing in question. To emphasize this point, Sadra introduces two kinds of motion. The first is the kind of motion which every material substance possesses as a concomitant of its existential constitution. In other words, this kind of motion exists as an essential property of corporeal things, and confirms substantial motion as a principle of 'substantiation'. The second kind of motion is that which takes place as an 'accident' as in the case of transposition (naql), transformation (taghayyur) or growth. Sadra calls the latter 'motion in motion' (harakah fi harakah). (33)