Treatise Chapter 1, Paragraphs 1-5

1.1 – This is a pretty typical invocation of God-as-First Principle to allow Scotus to understand what he already believes – in this case, God's existence. While it may be interesting to look at in terms of the medieval view on the place of philosophy (or the extent to which it can reach), this does not really concern the current exercise, and is not unique to Scotus.

1.2 – Scotus outlines the aim of the Treatise – to discover as much as he can of God's nature using the information we can glean from God's name, “I am who I am” (Ex 3:14). God is what it means to exist, the essence of existence, and though Scotus believes this, he wishes to discover it through a philosophical demonstration in order to understand it.

1.3 – In order to discover the nature of existence, Scotus decides to dig into the source of the “essential order” (defined in 1.5). Though there are many other properties of existence, Scotus believes that this essential order is the most basic one, and thus the best place to start in his investigation. The rest of the chapter is devoted to the four divisions of order – defining and understanding them – in order to discover how many types of essential orders there are.

1.4 – There are three requirements of a clear division within any subject of discussion:

1. the different parts that result from a division must be known and shown to be held within what is divided. For example, when dividing books into the species of “prose” and “poetry”, we've first got to acknowledge that these are the species we will divide the books into, and then we've got to show that both of them are species of the genus “book.”

2. the different parts must be known to be mutually exclusive. We have to know that prose is not a part of, contained within, nor overlaps with poetry, and vice-versa.

3. the classification must be exhaustive – there must be no thing within the genus that is not contained within the divisions. If there were a third type of book that did not fall into the species of prose and poetry, then our divisions would be inadequate, and would require another species of book in order to be a complete division of the genus “book.”

Scotus goes on to say that the first chapter is dedicated to the first requirement, while the others will be dealt with in the second, and so the rest of the first chapter is dedicated to defining the divisions.

1.5 – “Essential order” is a relation which can be asserted of both the causer and caused of each other, equally. “Causer” and “caused” (or, as Scotus puts it, “prior” and “posterior”) are enough, essentially, to divide up anything ordered. For example, look at the relationship between a parent and a child. The pair is an ordered one, with the parent as the causer and the child as the caused. Parent X is prior to child Y, and child Y is posterior to parent X. We speak of the relationship between the two equally, at least when speaking of both the causer and caused – such a relationship requires the both of them as participants. There cannot be a parent without a child, nor a child without a parent. But were child Y to have a child (call her Z) herself, she could not be spoken of as a parent/causer with regard to her own parent – Y's relationship with X regards her only as child/caused, and only the new relationship with Z will allow Y to be ordered as parent/causer.

This view of essential order is presented in opposition to the view that what is caused is ordered, and what is a causer exists beyond the order. This view of essential order is much more strict than the one Scotus proposes, as the only “causer” could be a being like God, who is uncaused and thus outside of the causal chain. As noted in the example of the last paragraph, every parent is a child in relation to some other parent, and so they are a part of the causal chain, within the order. In essence, Scotus is allowing essential order to have much more scope than the more rigid view proposed here, and avoiding circular logic in his proof of God's existence. If he were to choose the strict view of essential order, he would need to posit some sort of “uncaused cause” - a necessarily God-like being - just to get his proof started. Instead, he defines essential order without recourse to a being outside of the causal chain of existence, avoiding the assumption of his conclusion in the early stages of his proof.