Page 196

183 Doctrines: Basic Principles aggregates. We therefore seem to have the choice of accepting this passage as evidence that the atomists employed a concept of weight which had no connection with downward motion, or of concluding that Simplicius has here slipped into describing precosmic atoms in terms appropriate only to atoms within a cosmos. But here too a degree of reconciliation appears possible. We have seen that the evidence indicates that the motion of precosmic atoms was determined by antecedent interactions, and the outcome of each interaction must have been determined by the antecedent motions, shapes, and sizes of the colliding atoms. If we accept the conventional view, which has the almost unanimous support of the ancient sources, that these interactions were actual collisions, 12 it is plausible (though not directly attested) that the impact of a collision was thought to increase in proportion to the size of the impacting atom, not as a function of its extension, but as a function of its containing more matter. That is to say, it is plausible that the mass of an atom was conceived as a causal factor in atomic collisions, including precosmic collisions. If that is so, Simplicius' testimony that precosmic atoms were moved by their weight may be construed as a reference to this causal role of mass, while the apparently contrary evidence of ps-Plutarch and Stobaeus may be read as denying that precosmic atoms had weight as standardly conceived, i.e., as connoting a tendency to downward motion. The modification to the orthodox view thereby required is slight.13 D. Furley (Furley 29, chs. 7 and 8) also rejects the orthodox view, but for a different reason. He maintains that the centripetal tendency of atoms in the cosmic swirl cannot amount to their having weight, since the swirl will explain movement towards the central axis, but not the tendency to gather at the midpoint of the axis (i.e., the earth), which is what the ancients understood by weight. But D. Kostan shows convincingly (Kostan 33) that the complex dynamics of a vortex do explain the tendency of particles of different densities to collect at different heights in the vortex. In any case, what is required is not that the atomists should have had an 12 The contrary evidence of Philoponus and its implications are considered below under 'The Void.' If that view is correct, then impact has to be reconstrued as repulsive force, allowing the thesis considered here to be reconstrued as the thesis that the repulsive force of an atom increases in direct proportion to its mass. 13 Similarly Lobl 12 and 13 argues in favour of the attribution to the atoms of an inherent motive force, similar to Newton's conception of inertial mass, directly proportional to the amount of matter in the body, causing the atom to persist in uniform motion until deflected by external force. Lobl's view is, however, stronger than the thesis that the impact of atoms in collisions is directly proportional to their mass, in that he conceives this force as a source of motion intrinsic to the atom, a conception which is not required by that thesis. See below, pp. 194-5.

The Atomists -- Leucippus and Democritus  

MACEDONIA is GREECE and will always be GREECE- (if they are desperate to steal a name, Monkeydonkeys suits them just fine) ΦΕΚ,ΚΚΕ,ΚΝΕ,ΚΟΜΜ...

The Atomists -- Leucippus and Democritus  

MACEDONIA is GREECE and will always be GREECE- (if they are desperate to steal a name, Monkeydonkeys suits them just fine) ΦΕΚ,ΚΚΕ,ΚΝΕ,ΚΟΜΜ...

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