Ockham Quodlibet I.4-5

In the next two questions Ockham discusses angels and physics. The first asks whether an angel is in a place through his substance. Ockham first defines place in Aristotelian terms as the terminus of the containing body of what is in place, and then distinguishes between being in place circumscriptively and definitively. The first is when part of the placed is in part of the place and the whole is in the whole place. The second is when the whole placed is in the whole place - as Christ is in the Eucharist.

So then, an angel can be in place definitively but not circumscriptively. Ockham doesn't say this, but the case seems to me to be basically parallel to the way the human mind is in the body: the angel can be in any place the way that my body is the place of my mind. An angel is not in place the way God is, for God is present both to this place and also to every other place at once, which is not true of an angel. Furthermore, an angel cannot have a point as his place, since points as places do not exist. If there were real indivisible points which were the terminus of a containing body, the angel could be contained by them, but there aren't. Furthermore, there is a maximum size of the place an angel can be present at, since he is finite and limited by nature, but Ockham makes no effort to determine what this size might be. There is no minimum-sized place, and angels can coexist in a single place. Although O. doesn't draw the connection, it seems that this implies there is no limit to the number of angels that can dance on the head of a pin. This question, however, has been resolved elsewhere.

Question five builds on four to ask whether angels can be moved in place. First he defines local motion as "the successive coexistence, without an intervening rest, of something continually existing in place through diverse places" [motus localis est coexistentia successiva, sine quiete media, alicuius continue existentis in loco diversis locis].

The reason it seems that angels cannot be moved is their impartibility and indivisibility. Wouldn't any change of place for an indivisible substance have to be instantaneous? Ockham replies that when Aristotle states that in motion you always have a part of the moved in one place and part in another, he is only speaking about things which exist in place circumscriptively; but as we just saw, angels are not in place this way, but definitively. The angel's change in place happens in accordance with the manner in which he occupies a place even at rest.

Finally, in replying to an obscure objection based on a comment by Walter Chatton, Ockham gives an interesting counterfactual argument that sounds like modern possible-worlds talk. The discussion in this section is about how many things have to exist in order to verify a proposition. The Chatton-inspired objection states that in order to verify that an angel is created by God a period of time, or at least an instant, must exist for the verification to take place. I translate the counter-argument:

Assume that first of all God creates an angel together with a book, in which the proposition ["this angel is created by God"] is written, without [creating] the world; afterwards he creates the world, along with motion and time; afterwards he destroys the world and motion and time, [so that the state of things is] as before. Then this proposition "this angel is created by God" is true before the creation of the world, and after the destruction of the world it is false; and nevertheless as many things exist after the destruction of the world as there were before creation, and nevertheless it was then true and now is false. From which it is manifestly clear that sometimes three things are sufficient to verify this proposition, and sometimes they are not sufficient.

Since this is absurd, Ockham denies that time is a necessary condition for the truth of any proposition. What does this have to do with local motion? I have to admit that's rather obscure to me.