What is substance and what items in the world count as substances? This is the question Aristotle tries to tackle in book Zeta in his Metaphysics. To be sure, the question what items in the world count as substances already makes manifest a major turn when comparing it to the Platonic Forms. It is, as we shall see, a question of metaphysical order, of applied ontology. What is the total inventory of ‘real’ items in this world? How do they come about and how do they remain in existence? In book Zeta Aristotle sets out to consider a few classical candidate substances; bodies, animals, plants, the elements, compounds of elements, the heavenly bodies, the ‘limits of body’, surface, line, point and unit, eternal substances, Platonic form and mathematical entities. What one could argue is that, for Aristotle, the real question does not really amount to give a fair hearing to all of these would-be-substances, but to ask whether or not one should admit substances which are immune to processes of movement and change, inaccessible to the senses and capable of existence in detachment from the sensible world (see Lawson-Tancred’s translation). So, Aristotle asks: is it possible to construct a realist and, as we shall see, materialist metaphysics? Ofcourse, supposing Aristotle would really call his metaphysical endeavor ‘realist’ or ‘materialist’ is absurd, but we are using him here for ‘contemporary purposes’.
A crucial idea for Aristotle is that of ‘form’. We find our first thread here, because what Aristotle is after is crucially an ‘immanent form’; one that is not apart from the sensible or the total inventory of real items in the world, but with them. Ofcourse, what Aristotle is after here is not only to bring Forms down to earth, but to claim in the same stride that they are not created. Forms (with an f) persists unchanged through the production, while matter is changed. Nevertheless what concerns us here is the fact that they are produced. In fact, for Aristotle, everything is produced in some way, whether by spontaneity, skill or natural causes. This act of production consists of a compound of matter and form. Form is here imposed on matter, but depends on it at the same time; there can’t be any forms above or beyond matter, for that would lead back to Platonism. In this sense, what Aristotle is doing here is developing a minimalist ontology; he is trying to find that amount of being, that type of being which all beings share. Moreover, he is making this minimal ontological similarity into substance, into a first principle.
For Aristotle first principles are first causes. This is an activity, an ontological production. So, after having revalued matter and affirming the totally of the ever changing, undetermined sensible world we arrive here at the question of action, of immanent action and ontology. This topics directly relate to Aristotle’s ideas of potentiality and actuality, in which we find a dilemma Aristotle does not fully resolve, since it leads him back (or forth) to the acceptance of Oneness, of a First Cause and a First Substance. We will go into this problem in a following post.