How do we explain change? Maybe we remember our basic physics classes in high school: there is an object, held up in the air (by our hand or by part of some hacked-together Rube Goldberg device). It has potential energy. Then it gets dropped, at which point the potential energy is converted to kinetic energy.
This is more or less the Aristotelian notion of change (yes, I know there are problems, but it's an illustration - work with me here). We can apply this to other forms of change as well. For example, an acorn falls to the ground and resists being eaten by a squirrel. It is nourished in the soil and in time becomes a rabbit. Wait - that makes no sense. Acorns become oak trees, not rabbits. Why? We say that the acorn is potentially an oak tree and not potentially a rabbit. It is not the oak tree yet, but this is a different sort of not-being than the way in which it is not a rabbit. In time it will actually be the oak tree, given whatever there is that actualizes its potential (nutriments in the soil, water, etc.). So things potentially are certain other things (or potentially have certain other states) which can be actualized in the right circumstances.
The Aristotelian analysis requires these to be separate principles - actuality and potentiality, and we might also say the form of something (as it actually is) together with its matter (what makes it up). Matter is potential to receive a form. This makes some intuitive sense - when something changes, it both becomes different and stays the same. If I eradicated the acorn and then put an oak tree in its place, we would not say that the acorn changed into the tree. But at the same time, if nothing ever was different, there would be no change either. So the form must in some way become different (accidentally or essentially) while the matter stays the same in order for change to occur.
But here's the problem: we can never refer to matter itself. We also refer to some arrangement of that matter. We can talk about the way the acorn is currently structured to talk about how it will turn into a tree. In fact, it is difficult to see what we would need beyond its current form to explain its later form. Potentiality and matter are just roundabout ways of talking of current form and actuality with reference to latter form and actuality. It is as if we had two different coordinate systems looking at the same reality, but with the twist that actuality seems to be prior. All talk of potentiality is talk of actuality in disguise. Actuality carries monetary value, while potentiality consists of written slips of paper for a set number of greenbacks. So let's get parsimonious.
How do we explain change without potentiality then? The problem might be in thinking of "form" and "actuality" as something static. Things don't stand still, though. Everything is already caught up in some network of force. Even the earth which seems still is in tension with itself, as we discover when a tsunami hits. The actuality at any given instance is directional (or "telic", if you will) - it is what it is *doing* rather than what it statically *is*. When we talk of the potentiality of the acorn to become an oak tree, what we mean is that, given that dynamic nature of the acorn's present form, it would naturally become an oak if it follows that trajectory. But that oak tree is not now real - it is merely a way of describing what is actual through a hopeful prediction of the future. The oak tree is a hypothesis which is not now actual, and perhaps will never be, but which helps to organize our experience in the meantime. It doesn't need any separate principle beyond the fact that the acorn is currently in a state of growing, of responding to the soil around it, etc.
Potentiality has a merely pragmatic status, not a metaphysical one. The real principle, which is singular, is dynamic activity. This is resolvable into the current state and its direction of force (matter and energy?), but only as a conceptual distinction. How is this not just a return to the Aristotelian system, then? Because "actuality" is not the current state abstracted from its potential, but is the dynamic activity itself. Likewise, the direction of force is not the potential, but is just as much the actuality of the thing. In addition, these two moments are not metaphysical principles, but requirements of our minds for understanding the world. It seems perfectly possible that a perfect intellect would not need these crutches. We experience change because of who we are just as much because of how the world is.
What are the implications of this? We can still talk of potential, it serves a perfectly good pragmatic purpose, but it doesn't carry any metaphysical weight. Things don't change because some external actualizer acts on them, but have their own intrinsic power of self-actualizing (at least when I try to talk about it in Aristotelian terms, which are inaccurate; it's the best I have at the moment, though, so I have to ask readers to put aside surface incongruities and look at the meaning of what I say).
Further, it makes it easier to talk about all things as interconnected. When you have substances, they each have their own integrity, and you have to explain how they influence each other. But with an analysis of dynamic activity, everything already is by its very nature (speaking of its own "nature" in a pragmatic sense) affecting everything else. Aristotle's system is leaning in this direction with its analysis of act, but I'm going a step further - everything is completely constituted by how it fits into the overall network of forces. That is primary, and the substantial stability is an epiphenomenon - not vice versa. Substance is an abstraction from Reality (Indra's Web, suchness, shunyata, however you want to put it), not the basis. It is a perfectly good abstraction for getting around the world, which is all most people need, but common sense makes for poor metaphysics.
This also makes more sense of contemporary science in matters such as inertia (things naturally continue a line of force, whether fast, slow, in motion, or in rest, rather than going to some "natural place") and gravity (things naturally tend toward a place set by their environment, not by their own natures). Directionality, force, and environment determine the intrinsic nature of a thing; it is not always something accidental and violent.
