I have just recently found out what solipsism is, but nevertheless i am a convict solipsist and am also surprised there aren’t more of us around.
I actually think the only reason people reject solipsism is that they didn’t understood it.
Solipsism is the belief that only my impressions exist. That means, there is no World, but only my impression of a World. And from that this conclusion is taken: nothing matters, for they are only my impressions.
I do have a different idea of what solipsism is, but to make things clear let me call my idea of it Solipsism-I. I here stands for Importance-argument.
Basically, i do not grant that from “only my impressions exist” you can derive the conclusion that “nothing matters”. There is a logical fallacy here, and it is as such: if everything that exist is impression, and if something must be important, then the important things must be impressions too. The argument that a solipsist would “not care” is actually about a non-solipsist that did live in a solipsist world. In other words, this criticism of solipsism stems from either not understanding it or deliberately ignoring logic to sustain a belief.
But with or without fallacy, they are my impressions, and i do have ’em, so i care about ’em. So i do not want to feel pain, for example. Then, i would not disregard parts of my perceptions that imply future pain. For example, if i see a sabertooth-tiger behind a tree i will run, because i do not want to feel pain and not at all because the tiger exists independent of me. I do no care about the existence of the tiger at all. I want the existence of the tiger to f-itself.
Therefore, even if only my impressions exist, i can still have a model-of-the-world. I can still probe my impressions for regularities and constraints, for ways that i can explore them (so as to have more pleasure, or less pain, or more complexity, or whatever). I can also have hypothesis about myself and how i came into being — all of it extrapolated from my impressions.
So we have two different solipsisms, Solipsism-I and the other (what shall i call it? Solipsism-O, maybe, for Old, or Objectivist?). But there are other options.
In the end, Solipsism is just another interpretation (but without any logical difference) of Empiricism, so we might even say Solipsism-E.
We have Solipsist-H (for Hedonism), which is as Solipsism-O with the clause that impressions can be ranked by the level of pleasure they carry. This leads to Utilitarianism and i believe that it is just a mistakenly simplified understanding of the basic decision process of people.
We have Solipsism-M (for Moralism), in which every experience is either Good [God-ly] or Bad, thus rendering the whole of experience into a consequence of a single, usually religious or familiar, experience. I call it solipsism because goodness and badness are no more a judgment about things, they are the very matter of things.
And we also have the very curious Solipsism-W (for Wittgenstein), where everything is either false of true. The world for Wittgenstein is just a consequence of a strict, binary, unfailing, logical system. Thought is the substance of experience, and not the other way around. Curiously this tends to become very sensualist. Also, it is much more sincere of Wittgenstein to accept his solipsism than Descartes who claimed to know something he didn’t.