Hello. Thanks for all the great answers so far. A (seemingly) quick question. If everything is determined, does this mean that everything is necessary and nothing is contingent. Because if determined means 'could not be otherwise' then isn't that the same as saying it is necessary? Thank you, Christina

Determinism is a thesis about the relations between states (or events) in the universe. A deterministic universe is one in which, holding fixed the past states (or events) and the laws of nature, there is only one possible future set of states (or events). So, it might appear that determinism means that nothing is contingent or could happen otherwise. But that appearance is misleading, because the past or the laws were not necessary and they could have been different. If they had been different than they actually are, then the future events would be different than they actually will be.

If determinism meant that everything is necessary, then it would mean that there is only one possible universe. Nothing could be or could have been different than it is. That doesn't fit with the way we think about possibility. There are lots of possible universes--lots of ways things might have been or might be. But if determinism is true, the only way the present or future could be different than they actually are is if the past or laws were different than they actually were. I think this actually accords with the way we think about most (or all) events in our universe. The tree fell in the forest at this time and in this way. Could it have fallen in a slightly different way (or time)? Sure, but only if something had been slightly different leading up to its falling--the speed or direction of the wind, the saturation of the ground, the strength of the roots, etc. But for those things to be different, earlier things would have had to be different. And so on.

Perhaps our decisions are no different (I'm assuming you had the issue of free will in mind when you asked this question). You consider various options about what to order for lunch (or what major to pick or career path to follow or whom to marry!) After deliberation, you decide on X. Could you have chosen Y? Well, if determinism is true, only if something had been slightly different, such as the considerations you thought about or the strength of certain desires you had. And for those to be different, something earlier would have had to be different. And so on. But determinism does not rule out those possibilities. And if determinism is false, then it seems your decisions could be different for no reason at all, which doesn't sound so great either.

Lots more to say, but I hope this gives you something to think about...

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