Evolutionism is the philosophy of evolution affirmed in the previous theses.
Mechanicism is the doctrine which holds that all things are an aggregate of atoms lacking powers and properties, and endowed
only with extrinsic mechanical motion.29 Biological Mechanicism is atomism applied to organic nature.30
Rigid Mechanicism is the theory that corporal bodies have only local motion, and from these changes are explained all of
the phenomena of the world. In short, there is no force or activity distinct from passive motion. In Evolutionism only natural
selection would be possible. This is the position of the Positivists.31
Mitigated Mechanicism (also called Dynamic Atomism) is the doctrine which holds extended atoms, motion, and external motive
forces, such as impetus; however, there are no intrinsic forces.32
Merism is the doctrine that the organic body is nothing more than an aggregate resulting from the additive summation of
cells, chromosomes, and genes; the latter, in turn are mere aggregates of molecules, atoms, electrons and the like.33
Incompatible in this case indicates that Mechanicism would not provide a sufficent reason for Evolutionism.
Life is defined by Aristotle as "movement not communicated and immanent" (Aristotle De Anima 2. 1. 403 b 16).34
Aquinas agrees that life is the power of immanent movement (Aquinas Liber de Causis 18).35 Life is predicated
analogically of plants, animals, and man.
