Atemporal Idealistic Solipsism

Consider two theories of the universe:

1. The universe consists of a large amount of matter spread throughout a vast amount of space that has existed since the universe began some 14 billion years ago. The universe began in a condensed state and experienced a long stage of expansion where stars and planets and life formed. The behavior of matter is governed by complex physical laws.

2. The universe consists in a single conscious experience occupied by a single mind at a single time. There is no matter. There are no laws. Nothing changes.


Both options seem like epistemic possibilities to me. Even if (2) is a weird skeptical scenario, it could be true. We should be 100% confident that it is false.



So how do we evaluate which theory is more credible? We should look to their individual theoretical virtues.


Theory 1 is fairly unified -- it suggests an internally coherent explanation of our evidence that is somewhat parsimonious (all things considered) given that it starts with a relatively homogeneous stuff and explains the complexity we see through the operation of simple physical laws. Furthermore, it is aesthetically pleasing. It is a neat little theory. It is totally consistent with what evidence we have.

Theory 2, on the other hand, is so simple that it lacks any possibility of unification. On fit with the evidence, it seems to do as well as theory 1, at least if we take our evidence to be constituted by only our present conscious experiences, which, on the theory, would have to be the only thing to exist. Theory 2 is not especially aesthetically pleasing -- it isn't neatly wrapped up and internally coherent, but it is extremely parsimonious.


If parsimony is a significant theoretical virtue that generally outweighs internal coherence and aesthetic tidiness, then Theory 2 looks like a much more credible theory than Theory 1. There seems to be a pretty straightforward argument to thinking that we should assign it much much more credence then we actually do. I tend to think that this is right. Theory 2 is a very inherently plausible theory of reality. However, it would be very extreme to think that we should actually prefer it to Theory 1.




The most plausible way to reject the theory would be to argue that we must include more evidence then we generally do. We should not just include our present evidence when deciding fit, we should consider what evidence we have had in the recent past.  Our recent evidence would serve to rule out Theory 2.

This response seems to proves too much. Theory 2 should be an epistemic possibility. It seems to fit with the evidence that we have. Someone who rules it out out of hand is acting epistemically impetuous. If we can rule it out, then we shouldn't treat it as an epistemic possibility. This goes too far.

Thus, it seems that we have a dilemma. Unless we take our evidence to include things that would rule out Theory 2, we should prefer it over Theory 1.