So much television sci-fi is about the dangers attendant upon a Tear in the Fabric of Reality, or a Tear in the Universe, or a Rift Between Worlds, because scriptwriters need their fictional dangers to be readily understandable, and, even if we don’t know quite how it would work, we can believe that a tear in the fabric of reality would be bad.

The distinction between potency and act was discovered because the Greek philosophers (the ancient ones) thought that they had, in fact, found a tear in the fabric of reality. That tear was an apparent contradiction between the world of ideas and the world of the senses. It’s usually expressed by the question, “How do we reconcile the One and the Many?” which sounds very Jedi, but isn’t.

‘The One’ is understood in the mind; it’s the idea ‘Being’, a single idea which never changes, which is drawn from a single, unchanging reality that we find everywhere (there are no patches of Nothing in the world.) ‘The Many’ are first perceived by our senses; they are the multiple, changing things that we find in the world.

The One is understood through principles such as ‘Being is Being,’ and ‘Being is not Non-Being.’ This is more important than it sounds. You might say, “Well, I don’t really know what you mean by Being, but I know enough grammar to know that obviously Being can’t be Non-Being, because that would be a contradiction.” But that’s exactly the point. The principle is a declaration of the underlying coherence and consistent-ness of reality. “Being is One,” promised that wherever you were, you’d find this one constant thing that your mind would always grasp by an instinct so quick you’d hardly know you possessed it. Thus, this principle is also about the intelligibility of reality, because we understand this principle of non-contradiction with our intellects.

However, when you turn to the world of the senses, when you stop thinking of Being and start looking at beings, you notice that even though Things are Things, and even though identity is pretty fixed (either you have cancer or you don’t; if that thing is a dog, it’s not a potato), even so, every thing seems to be becoming another thing. Things are born, grow old and die. They get carved into new shapes, they melt, they fry, they get encrusted with sugar. A lump of silver gets stamped with an image, and suddenly it’s a coin, with a value it didn’t have before it was stamped. Or, if things don’t change entirely, they change in part – they are here and now they’re there; they’re hot and then cold, and so on. Change is everywhere. Motion is everywhere – motion being that passage from one way of being a thing to another way of being a thing.

How is this possible? How can there be single, unchanging Being apprehended by the intellect, and the multiple, changing beings apprehended by the senses?  Which is the truest reality – Being, or becoming? There was a rift between worlds; if they couldn’t co-exist, one of them had to go.

Two different solutions were proposed.

Parmenides concluded that the principles were so indisputable that the evidence of the sense world had to be false. So, he argued that that motion and change was an illusion and things weren’t really becoming other things at all. Things Just Were. And, since the only real thing was Being, this led to the idea that multiplicity was an illusion, meaning that there really aren’t lots of things in the universe at all; there’s just One Being That Looks Like Lots of Things.

Heraclitus took the opposite view, and concluded that the principle was the illusion, and that reality consists of beings in constant motion. Everything is in a process of perpetual becoming, and that’s it.  (You can thank Heraclitus for all those business motivational speakers who go round saying, “Change is the only constant,” and things like that.)

You’ve heard some people say that the journey is more important than the destination. For Parmenides, the journey was an illusion, and everything had arrived. For Heraclitus, there was no arrival, and everything was constant journey. Either solution affected your attitude to your intellect, your senses, the universe, and God.

Parmenides’ solution (everything is One) eventually generates doubt about the trustworthiness of the senses. It also leads to a kind of pantheism which turns everything into God. It hasn’t proved enduringly popular, because it’s hard to apply to real life.  “The multiplicity of beings is an illusion, and we are all One,” might do for a pick-up line at a tree-planting Gaia festival – especially if you want the girl to ignore the distinctions between the individuals in your polyamorous cult – but, ultimately, most of us don’t feel that individuality is fake. We also don’t feel like we’re God. Similarly, it’s pretty hard to believe that all change is illusory when you’re getting out of bed at 5:45 on a winter’s morning. I suppose there might be a Zen Master somewhere consoling himself with the thought, “Cold and Heat are One,” but try telling a woman at her child’s grave that all change is an illusion, and see what happens.

Heraclitus’ solution (everything is motion) leads to eventual doubt about the trustworthiness of ideas. It also leads to a kind of pantheism that pulls God down to our level, so that people say things about how God is evolving, just like man, and how He’s becoming God. This set of ideas is easier for most people to work with, because we look at things more often than we look at principles. The evidence of the senses is always before us (and it’s easier to set aside thoughts about Being in favour of eyesight when you’re at a set of traffic lights and your safety depends upon telling red from green.) Also, even though, deep down, most of us know we are not Just Like God, we’re still able to believe that God is Just Like Us. (This is why there are more religions telling you that God has a body than there are telling you that you are a pure spirit.)

Enter Aristotle…