So what if there is no reality, and the universe is a simulation, or a hologram, or a dream in the mind of god? As far as I'm concerned, it SEEMS real, and I have to deal with it. I process the information I receive through my senses and I have to process it as if it were real. If I do it right, it feels good. If I don't, it hurts. That is all the "real" that matters.

Whatever my "consciousness" (or soul, or spirit, or mind) is, it reacts to its perceived environment as if it were real. If the universe weren't there at all nothing would change from my point of view. I still have to look and act because when I don't things only seem to get worse. And "seeming" to get worse (or better) is indistinguishable from a hologram or a simulation.

Three thousand years ago Democritus taught that the only thing that existed was atoms and the void. Today, the physicists tell us that reality is just particles and waves, forces and fields. The religions teach us that God has put us in a cage and we have to follow the rules he makes up for us.

Those options are, from our point of view, indistinguishable. But we still have (perceived, if not actual) needs, desires, emotions, and relationships with others. Things feel good, or they hurt. They are fun, or they are boring. We believe they're there and they're not, or we don't believe in them and they are. Either way, it makes no difference. We have no way of knowing what the world is, we only can tell what it looks like. We don't even know if it looks the same to all of us. We don't even know for sure if there are any 'others of us' out there at all. All I really am sure of is that I exist, and I'm not even sure of that.

So when there's a knock at the door, I have no choice but to open it.