Oh, you’re a solipsist? You believe reality is an illusion and trees don’t really exist? I’m somewhat similar, I’m an antirealist. I recognise that reality is an illusion, but I still choose to believe in it until it can be overthrown. If we teach enough people how to reshape their beliefs and perceptions, then we can decide for ourselves whether trees exist. But at present, I need to believe in trees in order to inhabit consensus reality and communicate efficiently with the people who live here. It’s cool that you don’t believe in trees, though!