Istvan Bodnar (ELTE/CEU, Budapest), The Case of Aristotelian Celestial Mechanics

  

 

Monday, April 29th, at 18:00

Gilman Building, Hall 449

 

Chair: Leo Corry

 

 

Aristotle invokes in his account of celestial motion three explanatory factors: these motions are the natural circular motions of the special celestial element, they also exhibit something like the complexity of the motion of living beings, and they are under the causal influence of some external unmoved mover, or movers. Here I will concentrate on the similarities of celestial motions to animal motion, and consider two large topics within animal motion, both of them connected to contemporary mechanics. First, the requirement that animal motion occurs against a support, and second that it can have the complexity it has because of the internal setup of the animal, which is like the machinery of moving puppets, with the crucial difference that the internal configuration of living beings is malleable and able to change according to the state of the environment and of the animal itself.

As it will turn out, neither of these mechanical considerations is applicable to the case of celestial motions. Instead of a ‘celestial mechanics’ then, we will have to employ the different explanatory framework of Aristotelian natural motions. Nevertheless, even within the context of natural motions we will have to tackle how and to what extent some of the mechanical considerations are transferrable to the case of celestial motions. Furthermore one needs to address the issue what conceptual resources Aristotle has at his disposal so that he can admit a complex natural motion only a single component of which is strictly speaking the natural motion of the moving entity.