David Hume called causation the “cement of the universe”, and he was convinced that psychologically and in our practices, we can’t do without it.
Yet he was famously sceptical of any attempt to analyze causation in terms of necessary connections. For him, causation can only be defined in terms of a constant conjunction in space and time, and that is, I would add, no causation at all, but correlation. For every two events that seem causally connected can also, and without loss of the phenomenon, be described as just the first event, followed by the second. It’s really “just one damn thing after another”. It seems to me we still cannot, will not and need not make sense of the notion of causation (virtually no progress has been made since Hume's time).
There seems no need for another sort connection besides the spatio-temporal one, nor do we perceive any. In philosophy, a Hume world is a possible world defined in this way. All the phenomena are the same, but no necessary connections hold between the supposed relata. Maybe one should best imagine such a world as a game of life-world, but without a fundamental level governed by laws and forces; or as a movie, made of frames that are not intrinsically connected to each other. So, however strong the psychological forces that drive humans to accept further mysterious connections: Shouldn't we just stop worrying and accept living in a Hume world? Or are there actual arguments in favour of "real" causation?
Yes. There's the problem of order. What accounts for all the order in the world?It is remarkably ordered. If no special connections hold between events, why isn’t the world pure chaos? Or at least much more disordered? When two billard balls collide, never does one turn into an pink elephant.To explain this, men came up with laws of nature (self-sustained or enforced by a higher being).
So, there's the paradox: On the one hand, we have to postulate special connections to account for an orderly world like ours; on the other, we cannot give a proper account of these connections.
Inflationary cosmology to the rescue.
I won't go into the details (but see the nontechnical explanation and some further philosophical implications here).
Suffice it to say that
1) inflationary cosmology is mainstream physics, and
2) it postulates a spatially infinite universe in which every event with nonzero probability is realized infinitely many times.
How does this help to solve our paradox? The solution seems straightforward:
In an infinite universe of the right kind, order can locally emerge out of random events. Our universe is of the right kind.
So, we can account for the order in our observed (local) part of the universe.
Random events just happen, one after another, there is no need for mysterious causal connections. We throw them out but keep the order.
Q: But if this is true, it’s the end of the world. Thinking, action, science, biases and many, many more concepts are causal ones. How can we do without them?
A: life is hard, get over it.
Q: But the theory is untestable?!
A: Falsificationism is dead; we have other evidences in favour (see below).
Q: But isn’t the theory self-defeating?
A: It is certainly odd to have a theory informed by experiences and high-level physics that tells us that, strictly speaking, there are no experiences or sciences. But it doesn’t seem incoherent to me climb the ladder and then throw it away.
And, looking at the bright side:
In addition to being non-mysterious and conceptually sparse, this might allow to solve some additional (would-be?) hard problems:
qualia, clustering of tropes, time travel-paradoxes, indeterministic processes: All easy or trivial when a thouroughly indeterministic universe is considered.
So. What do you think – if you can?