Determinism
The future doesn't exist.
I'm a determinist. I think that reality is causally closed. I don't think there is magical influence that is outside material reality.
A car is deterministic system that seems pretty predictable. There are various controls that determine it's behavior. When you turn the steering wheel to the right the car goes to the right - predictably. When a car isn't predictable then we say it's broken.
It seems that in principle if we know all the causes in a deterministic system then we can predict its future and retrodict it's past. If reality is a deterministic system then in principle we could predict the future and retrodict the past of reality if only we were omnipotent. We take the past as fixed and are tempted to take the future as fixed as well.
I've come to think that this is not the way things work. Reality isn't really very predictable. It's a mix of order and chaos that produces stars and planets and living things. It's pretty rare in nature that you find predictability like you find in (say) Paley's watch found on a heath.
Years ago I wrote a program that is a simulation of the electromagnetic field. I can place positive and negative poles on a plane and the program draws "lines of force" between them. The system is deterministic. It's a computer program after all. I find it has lots of unpredictable behavior.
I put 25 poles in a grid pattern and let it run doing it's thing drawing lines. Here's the result (shows image grid.jpg). 
That looks pretty predictable. A pattern with many repeated elements in a grid.
But if we zoom in on some detail we see a lot of unpredictability.
Each red pole has 16 lines radiating out that propagate towards a blue pole. The mechanism is not hard to comprehend. I place a 'speck' just outside a red pole.
The speck "listens' to the poles around it. The red poles say to the speck - go away. The blue poles say - come here. The speck integrates those calls to decide which way to step next drawing a line as it goes. That line goes from the red pole to a blue pole generally in a smooth curve.
But some of the lines don't form a smooth curve. Sometimes you get a sharp right angle turn. I imagine that that happens when the speck can't decide which pole is calling louder and steps around at random until it can 'decide' which way to go.
When we think of cause and effect we tend to think of chains of cause and effect and chains like that are predictable. That is, for each cause there is a predictable effect. If there are just 2 poles that the speck is listening to then the propagation of the lines is predictable. But when you get 4 poles the propagation is not predictable. That's because the 4 poles create a causal net and causal nets can have lots of unpredictability.
Reality shows the same sort of pattern of order and chaos that we see in even simple causal nets. From this I draw the conclusion that the future doesn't exist.
What do you think?
I open the floor
I present regular philosophy discussions in a virtual reality called Second Life.
I set a topic and people come as avatars and sit around a virtual table to discuss it.
Each week I write a short essay to set the topic.
I show a selection of them here.