Using personal preference or personal intuitions as priors instead of some objective measure along the lines of Solomonoff Induction
Solomonoff Induction is uncomputable, and even if you use a computable approximation, you can't calculate it because no-one's written a program to do that AFAIK.
So if you are trying to work out which hypothesis is simpler, how do you do that? You use your personal intuition.
Mathematical Platonism
I actually think this is plausible. The argument goes: can you imagine 2+2 equalling 3? Maybe this is a personal intuition thing, but it does feel like maths is discovered not invented. If I decided that the derivative of sin(X) is x^5, and used this maths to design an airplane, it wouldn't fly. The maths exists whether I want it to or not. In physics, the equation for the electron produced two results, and one was thrown away until the positron was discovered - the existence of the positron, which is a real, physical thing, could have been predicted by the mathematics.
This is the 'unreasonable effectiveness or mathematics'. If maths describes physics perfectly, and the electrons exist, then why don't the equations for the electrons exist to the same extent?
Now, if you buy this argument, and if chairs, tables and morality can be described in terms of maths, then maybe the platonic form of a chair exists, and maybe moral realism exists? Admittedly, this generalisation is a lot more dubious, for one thing there are probably a very large number of moral systems and chairs which can be mathematically described, so this argument is less 'there exists a perfect platonic form of a chair' and more 'there are an infinite number of platonic chairs'.
The existence of non-physical minds
One argument is to go for broke and argue that the physical world does not exist at all. We know the mental world exists, because we have experiences, so the simplest explanation is that only the mental world exists and the physical world is an illusion. This then leads to libertarian free will.
(I don't actually buy this argument, I'm just explaining it.)
Not looking at the world in a probabilistic way
Because its higher status to believe in something 110%, even if this is gibberish? Because having unreasonable faith is good psychosomatically?
You underestimate the power of the dark side epistemology.
One argument is to go for broke and argue that the physical world does not exist at all. We know the mental world exists, because we have experiences, so the simplest explanation is that only the mental world exists and the physical world is an illusion.
If you define the debate to be about 'mental world' exists, it's worth noting that 'mind' is an English word that very particular to English and doesn't have direct translations in most other languages.
For a while now I've been trying hard to understand philosophical viewpoints that defer from mine. Somewhere along the line I've picked up or developed a lot of the LW-typical viewpoints (not sure if this was because of LW, or if I developed them earlier and that's what later attracted me to LW), but I know there are a lot of smart people out there who disagree with those viewpoints. I've tried to read articles and books on this, but they either don't address what I'm looking for somehow, or they're so technical that I have a hard time following them. I've also talked at some length with a philosophy professor, but our conversations often seem to end with me still being confused and the professor being confused about what it is I might be confused about.
I'm thinking maybe it'll help to get some input from people who do intuitively agree with my viewpoints, hence this post. So, can someone please tell me what the central arguments or motivations are for promoting the following:
Epistemology:
Ontology / philosophy of mind:
I suspect I'm having trouble with the ontology issues because of my trouble understanding the epistemology issues. Specifically, I keep getting the impression that most (all?) of the arguments for the ontology issues boil down to trusting philosophical intuitions and/or the way people use words. Something along the following lines:
Or the equivalent using the way people talk about things.
But this just seems totally ludicrous to me. If we trust cognitive science, evolutionary psychology, etc., and if those fields give us perfectly plausible reasons for why we might intuitively feel this way / talk this way, even if it didn't reflect the truth, then what could possibly be your motivation for sticking to your intuitions anyway and using them to support some grand metaphysical theory?
The only thing I can think of is that people who support using intuitions like this say, "well, you're also ultimately basing yourself on intuitions for things like logic, existence of mind-independent objects, Occamian priors, and all the other viewpoints that you view as intuitively plausible, so I can jolly well use whatever intuitions I feel like too." But although I can hear such words and why they sound reasonable in a sense, they still seem totally crazy to me, although I'm not 100% sure why.
Any help would be appreciated.