In my last post, I argued that relativism may actually entail objectivity. In trying to think through what sort of objectivity would be entailed and how it comes about, I found myself thinking back to Neoplatonic models. So my purposes here are twofold: (1) to analyze the case of spatio-temporal relativity and show in what since space-time exists, and (2) to attempt to rehabilitate Neoplatonic modes of expression to show that they do in fact have sense and are not merely outdated linguistic games.
In Proclus' system, there are triads consisting of Unparticipated-Participated-Participant, or, perhaps better, Unpossessed-Possessed-Possessor. There is some Form, say of human being. It may be helpful to spell out what this Form is not. It is not a human being itself (and so escapes Aristotle's "third man" argument). It is not the universal "human being", which is a concept derived from our abstracting from individual human beings. The Form of human being is called by the name "human being" because it is their (formal) cause, and not because of what it itself is. It is not some abstract Form that could exist without concrete human beings, floating ethereally up in some Platonic heaven. It always exists along with participants; what is at question is the formal priority.
However, this Form itself is Unparticipated/Unpossessed. This is not the humanity of any particular human being; it is the formal cause of humanity as a particular reality. The humanity of any particular human being is the participated/possessed form. Every human being has their own humanity. The concrete human being is then the participant/possessor of the individual form.
How does this relate to spatio-temporal relativism? Let's start backwards. There are concrete physical entities inhabiting what we call time and space. These are the participants/possessors. Now, we can talk about their particular locations in time and space, which are the possessed/participated spatio-temporal frameworks. All actual spatio-temporal frameworks are (a) relative, and (b) based on concrete beings. (In addition, there are spatio-temporal frameworks which are purely formal and mathematical, which correspond to other features in Proclus' system which I will not explain here). There is no space-time existing apart from these frameworks, but rather, space-time is always a specific space-time for each being.
However, it is not as if we were purely equivocating on space-time for each individual. There is some reality there which allows for them all to join together in a spato-temporal reality, even though they participate in different frameworks. This would be the unparticipated/unpossessed Form. It itself is not space-time, or spatio-temporal; whatever involves space and time must exist in some given perspective. In other words, space and time are realities that we experience as located in given perspectives and make no sense without being perspectival. Space-time is always space-time as experienced by some entity.
However, there is something which allows all of the different perspectives to be. It cannot be space-time in general (which is merely an abstraction, since real space-time is always in a given perspective), nor can it be the space-time of any individual perspective (since this would only exist for that perspective). Instead, it is the formal cause of the space-time for all perspectives, as a particular formal reality which is not itself space-time. It is that ground upon which relative spatio-temporal frameworks can take place.
Why posit this ground, then? Why not just stop at the different relative positions and be done with it? The different relative positions (as determined by concrete, actually existing entities, and not first and foremost as mathematical forms) are still the only fully concrete realities in the Proclean model. However, they do not explain themselves. There is a community amongst them that needs to be explained, and if we stop at mere individuality, it is difficult to see how we do this. By positing an unparticipated Form of space-time, we can explain the spatio-temporal openness of one entity to another even though space and time can only exist and be described according to individual frameworks.