Physics VIII

Method

a. dialectical, philosophical
not demonstration
few specific observations
cf. confusion in Physics i.1

b. conclusions guide arguments
primacy of circular locomotion
nature of heavy and light are assumed

c. Platonic inheritance: divided line

eikasia                  pistis                                    dianoia                                    noesis
conjecture            belief                                    understanding                        reason

Arist:  art                        sublunary nature            celestial spheres             unmoved mover

d. Unmoved Mover: an Exercise in Natural Theology
from physics
from metaphysics
from psychology?

Synopsis

motion in general did not begin and will not end
-whatever is moved is moved by something else (nothing just starts)
forced motion
natural motion: animals, simple bodies
-moved, moved mover, unmoved mover (accidentally moved)
-cannot have an infinite series of movers
must be one thing at the beginning of the series
is continuous; should be single not plural
-it maintains the first motion: circular locomotion
-it cannot be a finite or infinite magnitude; must be without magnitude at circumference

viii.1
A. Does motion just spring into existence?
[canvass the endoxa]
motion cannot simply come into being from absolute rest
time cannot exist in absolute rest, so there is no time before motion
so time cannot cease

B. Will motion stop?
no, what is potentially something else does not cease that potentiality

viii.2
objections and responses to the position that change always is:
a. no change is eternal
yes, but these changes are between contraries
and not all changes are between contraries
b. inanimate change starts at some point
yes, but they must be started
c. animals can start themselves (in them there is a beginning of motion)
yes, but even in still animals there is some motion
or motion in the environment that stimulates them

viii.3
some things are always in motion, others always at rest, others sometimes in motion and sometimes at rest
a. Parmenides: all at rest: destroys physics
b. Heraclitus: all in motion: destroys physics; makes nonsense of contrary change
c. Some things at rest, others in motion: but the senses say otherwise

viii.4
whatever is moved is moved by something else, for
all movement is natural or unnatural
all unnatural movement is caused from outside
all natural movement is (ultimately) caused by an outside movement

viii.5
A. there cannot be an infinite series of movements
there must be a first mover
therefore, the first mover must be moved by itself

B. Where something moves itself there is a part that moves and a part that is moved
and the moving part is moved incidentally

viii.6
the unmoved first mover is eternal and one
the unmoved first mover is not moved even incidentally
since thus it could not cause a continuous motion
the primum mobile is eternal

viii.7
locomotion is prior to other forms of change
only locomotion is continuous

viii.8
circular locomotion is continuous and  infinite

viii.9
circular locomotion is the primary kind of locomotion
simpler than linear locomotion

viii.10
the unmoved mover is without magnitude and on the circumference of the universe
the unmoved mover cannot be either infinite or finite in magnitude
if finite, it could not be active for an infinite time