Summarizing Sinhababu
Can I present a robust argument in 200 or fewer words?
The argument is as follows.
Phenomenal introspection is the only reliable way of forming moral beliefs.
Phenomenal introspection informs us of only hedonism
Therefore, hedonism is true — pleasure is the only good. Phenomenal introspection involves reflecting on experiences and forming beliefs about what they’re like (e.g. I conclude that my yellow wall is bright and that itching is uncomfortable). Premise 2 is true — when we reflect on pleasure we conclude that it’s good and that pain is bad. Premise 1 is also true — other moral beliefs are arrived at through intuitions, but those are unreliable given that many people’s intuitions throughout history have supported slavery and genocide — and people’s moral intuitions lead to totally different disagreement. If some method of forming beliefs constantly contradicts itself and concludes genocide is good, then it’s unreliable, especially when we have no evolutionary reason to think that it’s reliable. However, phenomenal introspection is reliable; beings who can form reliable beliefs about their mental states are fitter than ones who can’t.
Thus, we should abandon every moral belief except that pleasure is good and pain is bad. And that gets us hedonic act utilitarianism. Objections?
I have a reply to this I decided to make into a blog post. I'd be happy to continue our other discussions in a blog exchange as well. Here's my response:
https://www.lanceindependent.com/post/phenomenal-introspection-and-hedonism
Premise One is False:
A. Something other then introspection allowed us to conclude that this very argument about morality is true, and thus form a moral belief.
B. Introspection can be false - one can be mistaken about their own feelings towards something. I.E. one might be convinced that they want to be ethical, when in reality what really motivates them is self-interest.
C. It seems implausible that *only* phoenominal introspection could lead to correct moral beliefs. If a hypothetical alien species were unable to introspect on the morality of sensations, why would they be unable to arrive at hedonism using all of the other considerations in favor of it you've listed ot in your posts?
D. Mental Insanity - Obviously in the extreme hypothetical, insanity impacts everything, but there are certainly situations where it could uniquely apply to moral introspection. Take someone with a special form of OCD, developed by me for the purpose of winning arguments on the internet. A person with this disease gets a creeping feeling that their stove is on - which will kill the mythical god Ra by stealing his light. Introspecting on this reveals a creeping feeling of sheer wrongness. This must be bad.
This is manifestly unreliable, because I could change this form of OCD into anything I wished.
Premise Two is False:
A. You didn't defend the "only" in the statement at all. That's a simple failure to carry your prima facie burden of persuasion. You can imagine a list of 500 other things that introspection could say is good here. (If this was a product of the wordcount limitation, you must revise!!!)
B. I think that many people's introspection would lend itself much better to desire furfillment. One might often deisre to have pleasure, but when one introspects, they can often come to believe that accomplishing their desires is good in itself.