In my experience atheists tend to dance around the KCA but they usually don't explain with clear words their point of disagreement.
In this context "universe" means " all phisical reality" (including time) universe simply means all the natural world.
The claim is that regardless if there was something before the big bang or not , there was an absolute begining at some point in the past.
So what is wrong with the KCA? Do you agree with premise 1? Do you agree with premise 2? Does the conclusion follows from the premises?
What exactly do you think is wrong with the argument? Please try to provide direct and clear answers.
There are only 3 alternatives
1 the universe (the physical/ natural world) came from nothing (literally nothing)
2 the universe has always existed, it is eternal
3 the universe has a cause (which by definition would have to be a supernatural cause)
So which one of these 3 alternatives do you pick? Or perhaps there is a fourth option that I haven't thought about.
What is wrong with the argument? That it is still used. since it is very easy to knock down. Well, for sure it shows its age, since it can make some sense only if we use very old physics. And I do not dance around dead horses, usually.
Both premises, and their combination, are not necessarily true. For instance (just a few)
1) "Begin to exist" assumes a time context. Unless you can define "begin" without "time". Time is not objective, as we learned from relativity, so it is not even clear what premise 1) means. Especially since you include time into the set of things that began to exist, which is clearly nonsensical. More importantly, "begin" assumes a time arrow as well (going from past to future passing through present), and the direction of time is a macroscopic phenomenon. A statistical one (Boltzmann, Rovelli). That is, it requires already an Universe in thermal imbalance to make sense.
2) That everything that begins to exists has a cause (assuming it makes sense despite 1)), is an empirical observation. We observe that in our universe. Extending it to the whole Universe (the context in which observations take place) is at danger of committing the composition fallacy. That is, properties applicable to the contained cannot be extended to the container, in general.
3) Since the fact that time has a direction is a macroscopical effect, it is definitely not applicable to the fundamental world. Microscopically, causality vanishes (cannot say what the cause or the effect is) since all directions of time are equivalent (unless we borrow the one of our lab, which is again macroscopic). Therefore, when the Universe "was" at fundamental level (and there were no labs around), saying that the alleged cause of the Universe, if any, was not an effect thereof instead, is question begging.
And so on and so on.
But let's analyze your alternatives:
1 the universe (the physical/ natural world) came from nothing (literally nothing)
--> You are using a tense verb (came) and a "from". You are assuming a time and space context in which space time contexts can come from. This is obviously meaningless (and circular).
2 the universe has always existed, it is eternal
-> This is not only possible but likely. All we have to do is to use a relativistic ontology of time (B-series), and come to the conclusion that our Universe is a block Universe. Actually, most of modern science has eliminated time from physics. Not all physicists agree, but many think that the block Universe (leading to eternalism) best corresponds to what we learned from Einstein (Rovelli, Greene). In that case, the Universe would be eternal (and unchanging, necessarily). The Big Bang and all the rest would then be events on an immutable spacetime surface. Existing eternally. This seems to be the case also if we include QM (Wheeler, de Witt).
3 the universe has a cause (which by definition would have to be a supernatural cause)
--> Assuming that the universe has a cause (despite all open points above), it is not necessarily a supernatural one. For instance, there are theories that postulate that the Universe spawned from another Universe that reached global equilibrium (see Carroll). Not to talk of eternal inflation, baby Universe sprouting out all of the "time", etc.
True, none of these theories are proved, but they are on the table, like your supernatural ones, so you have first to be sure that all naturalistic explanations are false, before having necessity of supernaturalism. Good luck with that. Probably, you think eternal and infinite regress is impossible, good luck with that too. I still have to see an argument that shows logical contradictions with infinite regress, even if our Universe is not the product of infinite regress.
Talking of infinite regress: it is even possible to have infinite regress that takes finite time. Ergo, an infinite chain of causality and yet a finite age. In that case, everything that began to exist has a cause and a bounded age, while there is no initial uncaused cause.
But I stop here. Listing all possible independent rebuttals of Kalam would turn this into a monster post.
Ciao
- viole