if nothing means anything,
then why do we live still under the assumption
that it does, in fact, still mean something?
Just noticing that nihilism as a concept might be "fun" to think about or entertain, but when it comes down to it, no one has altered their life to suit these ideas. We still pretense to know right and wrong in our day to day actions. There is something deeper lying within our subconscious that directs us, something that we can't quite forget even though we try. It is higher than our thoughts because our thoughts move underneath it and our thoughts about what are or we should be are powerless to change a reality that we feel deeply within our very beings.
What I mean by this is- if we subscribe to nihilism and we believe that nothing means anything and that our lives are pointless and are only determined by our own will, then why don't we live this way? A life rightly conducted by this philosophy would lead us to always act in our own self-interest and to ignore the needs of others. In fact, when taken to its logical conclusion, a life by this philosophy should END, because why would we want to go on living in a world with pain in it and no reward or comfort for the pain?
Then, if, as we observe, many people hold a nihilistic view but VERY FEW live according to that view, then there must be something stopping us from behaving that way, something that exists regardless of our beliefs to the contrary. I can believe all I want that my neighbor's existence, mind, and heart, are entirely determined by my observation of them, but that doesn't stop me from having a conscience that tells me from being kind to them. I can believe that morals are not absolute, but it does not stop me from telling my neighbor that they are not being fair and their response, if morals did not exist, should instinctively be that fairness does not exist. However, their instinct is to argue that they are exempt or justified against my preexisting standard of fairness.
Thusly, a universal idea of fairness is presented in every aspect of our behavior and everyday. Even if we entertain ideas that a universal standard of morality is not true, we still have a universally agreed-upon conscience that manifests itself in our behavior and our interactions with each other.
And, why, then, is that there? Why do we still behave as if there is a moral standard even if we believe there is not?
I would propose that this moral standard is built into who we are as human beings. We cannot avoid it. We cannot ignore it (except in the case of the severely mentally ill). Something is driving us to a higher standard regardless of our ideas about it. Subsequently, this thing that drives us to that standard exists objectively and outside of whatever our ideas about it are. We cannot ignore it- so it must be unaffected by us.
This inkling, this conscience, within us is what, alone and by itself, proves that truth is real. We cannot change it, because we know that despite our efforts or thoughts otherwise, we still try to act according to it, whatever it is.