By "idealist" I'm referring to metaphysical idealism...that what fundamentally exists is mental, not physical. And by mental I mean either consciousness or existing only as an aspect of consciousness. For example, there is my conscious experience of a dream, and then there are the things that appear in my dreams that I am conscious of...houses and chairs and trees and people. Both categories of things are mental. The trees that appear in my dreams only exist as an aspect of the dream. And by "accidentalism" I mean the theory that nothing that exists or occurs is caused. There is nothing that connects or controls the flow of events. The only rule is that there are no rules to appeal to. So "idealist accidentalism"...the view that what exists is mental, and that there is no underlying process that explains or governs this existence. Explaining the order of our experience by positing the existence of orderly underlying processes (as with reductive physicalism, for example) is just begging the question...because then what explains the order of those underlying processes? The total amount of mystery was conserved. We just transferred the mystery to a new location - from our conscious experience to a hypothetical underlying process. We are unwilling to accept that our experiences "just are" orderly, so instead we appeal to an underlying process which "just is" orderly. "Ordinatio Ex Machina". Not only that, but this reductionist approach raises the question of why we would be so lucky as to have our conscious experiences generated by underlying processes that "cause" us to have correct knowledge of those very processes. We can only know what the underlying process causes us to know. Thus, the tendency to believe true things can't be a special feature of humans. Rather, it would be a special feature of the process that underlies human experience. Note that this is a problem with any rule-based explanation of reality, not just with reductive physicalism and the like. But the only alternative to a rule-based explanation of reality is accidentalism, isn't it?