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Showing posts with label Aristotle. Show all posts
Showing posts with label Aristotle. Show all posts

Friday, June 29, 2012

Aristotle's Physics (Book V-VIII)

Book V

The focus of Book V is on 'change', which, according to Aristotle can occur in one of three senses:  1) Accidentally; 2) Partially (something belonging to the object changes or moves); and 3) Directly (the thing itself moves or changes).  Change is always "from something to something".  'Coming to be' (change from nothing to something) or 'perishing' (change from something to nothing) cannot be considered true instances of change according to Aristotle because that which "is not" cannot possibly be in motion.  Motion is therefore always from "subject to subject" and never from subject to non-subject (or vis versa) and can be classified in three different ways:  1) Qualitative; 2) Quantitative; 3) Local.   Qualitative motion is also called alteration from one contrary to the other.  Quantitative motion involves increase or decrease between two contraries.  Local motion is another way to say 'locomotion'.

Book VI
In this Book, Aristotle contends that everything that changes, such as magnitude, time and motion, is continuious and "divisible into divisibles that are infinitely divisible."  Within time, however, there is one thing that is indivisible:  the present.  The 'present' is a boundary or limit between the past and the future and is therefore impossible to divide.  A good chunk of this chapter is taken up with refutations of Zeno's famous paradoxes using the principles that have been developed in the Physics up to this point.  Both Aristotle and Zeno agree (contra the Atomists) that space and time are continuous and divisible, but whereas Zeno's paradoxes presuppose the existance of 'actual' infinities, Aristotle avoids the trap with his inriguing concept of 'potential' infinities.

Book VII

Book VII has some fascinating theological undertones which are later developed at greater length in the Metaphysics.  The maxim of this Book is:  "Everything that is in motion must be moved by something."  But this immediately leads us right into the vexing problem of infinite regress which necessarily leads to a number of philosophical absurdities.  The conclusion:  "there must be some first movent (mover)." 

Book VIII

According to Aristotle, there are two possible candidates for the first cause of all motion and change.  It could either be a self-moving mover (like an animal) or it could an unmoved mover.  In order to avoid the problem of infinite regress and a first cause that is neither eternal nor continuous, he concludes that the first cause must be an eternal, unmoved mover.  This book contains a discussion on the kind of motion that such a first cause would produce, which in Aristotle's view, must be rotational or circular locomotion since this is the only form of motion which is both eternal and continuous.  In Aristotle's scheme, it would appear that the unmoved mover causes the circular motion of the heavenly spheres, and this motion, in turn, is the cause of all other kinds of motion and change.


Saturday, June 23, 2012

Aristotle's Physics (Books I-IV)

What follows is a brief summary of Aristotle's Physics, which I'm writing primarily for the benefit of my own memory and comprehension, but at the same time, I hope that this will be a help to anyone else who is plodding through Greek Philosophy in an attempt to come to a deeper understanding of the philosophical underpinnings of Christian thought.  Most of us who have gone through Seminary here in North America have done so without the benefit of a good old fashioned classical education, and as a result, the 'cart' of theology has been put before the 'horse' of philosophy.  The deeper I go into Historical Theology in my effort to understand the polemics of the Reformation (in the case of my research, the polemics surrounding the Eucharist), the more convinced I become that we cannot fully understand the Reformers or the theology of the Reformation if we do not take the time to understand their fundamental philosophical presuppositions.   Over the past year I've read most of Plato's major dialogues and bits and pieces of the Neo-Platonists, and now I'm digging deeper into Aristotle and (soon!) Aquinas. 

Book I

In Book I of the Physics, Aristotle deals primarily with the elements of a natural body.  In dealing first of all, with the age old philosophical problem of "the one and the many,"  he flatly denies that 'substance' can properly be the predicate of anything else. Various pre-Socratic philosophers who postulated that all things can be reduced to one single 'substance' have thereby missed the mark (ie. Thales -->all is water).  Instead, Aristotle argues that there must be at least two primary elements or first principles, since everything in nature that comes to be by a natural process either derives from, or tends toward, its contrary (ie. hot <---> cold).  These two contrary principles, however, do not constitute the substance of anything, and so Aristotle adds a third element which is the substratum upon which the contraries operate.  We are left therefore with three primary elements, or first principles, in nature:  1) form;  2) privation of form;  3) matter

Book II

The study of physics or 'nature' must deal with both form and matter according to Aristotle and not merely with matter.   A physicist who neglects form in his study of nature is not unlike a doctor who has a knowledge of "bile and phlegm"but is totally unconcerned with what actually constitutes health and sickness.  The physicist is therefore obligated to deal with all three primary elements of nature. 

What follows in this book is one of Aristotle's most important contributions to later scholastic theology, namely his famous four-fold causality.  A discussion on causality is included here, because "we cannot know anything about nature until we grasp the 'why' of it."  Here are the four causes as outlined by Aristotle: 1) Material Cause:  "that out of which a thing comes to be and which persists";  2) Formal Cause:  "the form or the archetype";  3) Efficient Cause:  "the primary source of the change or coming to rest";  4) Final cause: "that for the sake of which a thing is done."   Having outlined these four causes, he entertains the possibility of "chance" being a fifth cause.  His conclusion on this point is that spontaneity (that which pertains to inanimate objects) and chance (that which pertains to moral creatures) are posterior to both intelligence and nature, meaning that "however true it may be that the heavens are due to spontaneity, it will still be true that intelligence and nature will be prior causes off this all and of many things in it besides."

Implicit in Aristotle's conception of causality (specifically his 'final' cause) is the idea of teleology so despised today by radical Darwinian naturalists.  For Aristotle, nature has a purpose or telos, and everything that we find in nature tends toward its ultimate goal which is the full realization or actualization of its form.  Another way to put it is that there is a movement in nature from potentiality to actuality.  

Book III

This book begins with a discussion of motion, which Aristotle defines as "the fulfillment of what exists potentially, in so far as it exists potentially."  He lays the foundation here for later generations of Christian Theists by postulating  the possibility of something which can initiate movement which is itself unmoved - the so-called 'Unmoved Mover' which is arguably Aristotle's god... (or God??)

Since physics deals with spatial magnitudes and motion and time, each of which must be either finite or infinite, Aristotle includes here a lengthy discussion about "infinity".  He points out the difficulty of grappling with the infinite:  If we suppose that it exists we are led into many absurdities and contradictions (as we all learned in high school math!).  On the other hand, if we deny its existence we are forced to deal with a different set of difficulties and absurdities.  Aristotle's solution is that infinity exists potentially, but not actually. 

Book IV

Book IV begins with a discussion on 'Place' since we "all suppose that things which exist are somewhere".  This discussion, although somewhat tedious on the surface, has direct relevance to my MA thesis.  During the sixteenth century, Reformers engaged in an incredibly heated argument about the location of Christ's glorified and ascended body.  Was it in heaven as Zwingli, Vermigli and Calvin contended or was it omnipresent "in, with and under" the sacramental elements as Luther and his disciples argued through their doctrine of Ubiquity and 'consubstantiation'??  The Eucharistic debates of the 16th century between Reformed Protestants and Lutherans are really debates about Christology - but taken one step further, they are most fundamentally debates about the place of Christ's risen and ascended body.

According to Aristotle, "place is something distinct from bodies, and every sensible body is in place."  A philosophical problem immediately arises, however:  "if everything that exists has a place, place too will have a place, and so on ad infinitum" - and therefore we find ourselves stuck in an infinite regress!   Aristotle's conclusion in this discussion is that "the innermost motionless boundary of what contains is place."  He goes on in the course of the argument to deny the existence of a 'void' - defined as that a 'place' that exists separate from a body."

Book IV ends with an interesting discussion on Time.  According to Aristotle, there is an intimate relationship between time and movement, such that "time is neither movement nor independent of movement."  The relationship between time and motion has to do with 'succession', since both time and motion can be understood as examples of perpetual succession.  Not only do we measure movement by time, but we measure time by movement because they are mutually defining.