This Post Is A Lie: On Absurd Concepts of Truth

In class on Monday we discussed absurd concepts of truth, and the question was posed: "How do we know if anything is true or real? What if we are all dreaming? What if we are all really brains floating in jars, influendced to perceive this world as being 'real' when it is in fact false?" Though I think that both of these scenarios are extreamily absurd and farfetched, I like to consider them for the sake of a good debate. After all, how do we know for sure one way or another? My major discrepancy with these situations, and the accompanying claim that everything we perceive is 'false,' is that the concept of being 'true' or 'false' is (to the extent of my knowledge) a human-created way of thinking, or was at very least developed in the world that we may or may not be 'dreaming.' If this is so, then the concept of truth is just another lie that we are influcened to dream up while floating in our jars, therefore making its application completely irrelavant to any existance outside the one we believe to be 'real.' Based on this line of thought, I have personally come to the conclusion that, since the debate over truth exists in the world we seem to live in, we can safely apply it to the things that we perceive in it, whether or not we are being influenced to perceive our surroundings by an alternative reality.

What other ways of thinking might lead one to the conclusion that everything we perceive is false?