I think at the core of any person's considerations of Nihilism, Existentialism, Absurdism, and any other "isms" lol, is that no matter what is reasoned or felt, how a person proceeds comes down to choice and autonomy. That's going to mean and look differently for everyone depending on their situation, circumstances, health, etc.
I won't open up the box about free will. But let's just skip to the part where we know there is an answer, even if we'll never know what it is. Maybe we will know, but that doesn't change that it only "is what it is."
Let's say I have free will (whatever that technically means). Great, then of my own free will I expressed my thoughts here. Let's say I don't have free will. Great, then I didn't freely express my thoughts here, but still did nonetheless. Whether I'm free or not, or some weird mix of both, I either will or won't commit actions and agree or disagree with thoughts. I will still freely or unfreely consider the consequences of my thoughts and actions for the benefit or detriment of myself or others around me.
Whether we're free or not, if it's outside of our control to know, choose, or change the predicament, we are still living or not.
So I guess, no matter which ways a person reasons or doesn't reason, the question is still "What are they going to do about what they think or don't think?" Or if what can be done is limited or nothing at all, a person will still have to experience and interact with consciously existing if they are alive. This is adjacent to Camus' notion of "revolting against the absurd." I think Nietzsche's "Superman" idea is hitting on a similar concept too.
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