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9.3 Continuants (Substances) Which Endure Through Change?

We now come to the question of whether a concept of `substance', as at least `continuant', can be constructed using the above analysis of process and dispositions.

    A continuant has been defined (Johnson, [1924], III p. xx) to be `that which continues to exist throughout some limited or unlimited period of time, during which its inner states or its outer connections may be altering or remain unaltered'.   Johnson used the term `continuant' as against `substance', for the term `substance' is impaired by the fact that, in the history of philosophy, many diverse senses have been assigned to it, senses which give associations which are not wanted here. For example, though continuants can endure through change, they need only endure for at least a while, and not necessarily everlastingly, as many suppose that substances are required to do9.4. Further, since Locke at least, it has become obscure exactly how a substance is supposed to be related to its powers, qualities and properties, etc. `Substance' has come to be regarded as an `I know not what' which in some obscure manner `underlies' and `supports' its attributes.

    Ducasse [1964] has proposed `substant' for a new association-free term, but in some ways `continuant' is still preferable. This is because substants do more than just continue: Ducasse lists another five general features of substants, another five things which they are capable of doing:

  • acting (as an `enactor')
  • being in a state (as a `tenant')
  • affecting another substant (as an `agent')
  • being affected by another (as a `patient'),
  • changing into something completely different (as a `mutant'), as well as
  • enduring changes (as a `continuant').
As all these details presuppose a detailed analysis of the concept we are constructing, I will use the term `continuant' to refer to any particular individual being in the world which can continue to exist at least for a while, and can effect and undergo some change while remaining the same being (`same' in some sense to be elucidated).


9.3.1 Unchanging Continuants

We will first consider what particular things can endure through time, even if they are not permitted to change at all in that time. Since actual events are at definite places in spacetime (once they exist), the longest they may be said to endure is for the temporal aspect of their space-time region. If our initial events are separated by finite time intervals, then the events themselves do not endure from one event to the next. The only particulars that so far are certainly known to endure are the propensity fields themselves. They endure because their source and realisation events are separated in time, and, because the second event could have occurred earlier, the propensity for its occurring is distributed over all the intervening possible times. Considered as a particular thing, the whole propensity field therefore endures over the finite time interval between the events.

Admittedly, this endurance of propensity fields is not entirely conventional, for they extend `with one span' over temporal as well as spatial intervals, rather than being a real succession of spatial fields at successive times. It of course appears to us as if they move successively and continuously through different spatial regions between the events, but this does not mean that there is a continuous succession of actual entities, as we are really only looking at potentiality or propensity fields. It is a grave mistake to think that because something can occur at any time between two actual events, then something actually is occurring at those times: we must not confuse actualities and possibilities!

Since single propensity fields do endure, at least for a while, they can be regarded as the most basic continuants in that they never change so long as they continue to exist, and hence must remain the same even under the most technical and exacting sense of identity. Therefore we define unchanging continuant as a `separable propensity field.' They are unchanging, because they endure unchanging for their short while between two successive actual events. They can be viewed as `brittle' or `precarious' continuants, in that they cannot change in any way without becoming different continuant(s), yet while they do endure, they stay exactly the same, even staying at the same places in space-time.

Note that

although they are unchanging continuants, they do not prohibit natural change: only when they do lead to changes, they must mutate into something different,
they may still appear to change for us, if we change, for example, by moving our place of view during the time between two actual events for the continuant being observed, and
unchanging continuants in nature will typically only last for some small fraction of a second, the time between successive molecular collisions in typical solids, liquids, and gases.

The powers of any entity are what it is capable of doing and how it is capable of interacting. The ascription of powers is typically in the form described in chapter 2. The powers of a propensity field are given entirely by the spatiotemporal distribution of propensity within the field, along with the measure or description of the nature of the propensities at each place in the field. For, given the form of the field and the descriptions of its propensities, then one can predict exactly how the field is likely to interact with other fields in any given situation. This is because the `circumstances' are just the degrees of overlapping with other fields, and the actions that are possible in those circumstances are just those events to which the propensities are directed.  


9.3.2 Changeable Continuants

So far I have defined only particular unchanging continuants, as particular propensity fields. What about changeable continuants: continuants which can endure through certain changes to themselves but keeping the same powers and properties etc.? Since under a strict sense of identity, nothing can itself change or move in any way, and still remain the same particular, it will be necessary to relax this strictest sense of identity if a sense of `continued identity' is to be obtained. We want now a sense under which one continuant can undergo interactions and shift around, and not only remain unchanging between some pair of events.

Perhaps the most obvious relaxation is to allow the same substantial form over different places, so that the same continuant can at least move, as a whole, to extend over a different region of space and time. There is hence a sense of continued identity which treats two `unchanging continuants' as in fact the adjacent and successive stages of the same `changeable continuant' when

there is some event over which the two `unchanging continuants', as propensity fields, are extensively continuous with each other. This event would then be the product of the earlier continuant and the cause of the later one.
these two continuants have the same `substantial form' even though they do not extend over the same sets of places.

That is, for a changeable continuant to have continued identity, there must be a spatio-temporal continuity of the same substantial form.

A changeable, enduring continuant therefore retains the same substantial form and the full possession of all its powers through any changes or interactions it may pass, so long as it lasts. The above conditions do not imply that even a changeable continuant must last forever: there can be sufficiently radical events in which no outcoming continuant has all the powers that once constituted one of the ingoing continuants. There can be changes in which not all the powers of a continuant are preserved through the change.   Such changes could be called `substantial changes' because some continuant did not survive. Changes in which a wholly new continuant is formed can also be called substantial changes. Generation and decay events would be examples of substantial change, provided that what was generated or decayed was a single continuant, not merely an aggregate or arrangement of continuants. An example is the decay of a neutron, which in free space after about 18 minutes decays into separate proton, electron and neutrino fields, where none of the outgoing continuants has all the powers that the neutron once had 9.5 . Most of the other interactions of the neutron such as collisions and refractions etc. do preserve that continuant, as there is a continuity of its substantial form and of its powers.  

next up previous contents index
Next: 9.4 Questions about Substances Up: 9. A Theory of Previous: 9.2 Propensity Fields
Prof Ian Thompson


Author: I.J. Thompson (except as stated)