Mereological nihilism "Nothing is a proper part of anything."
Mathematical monism Max Tegmark - Our external physical reality is a mathematical structure.
Neutral Monism One sort of thing fundamentally exists, to which both the mental and the physical can be reduced.
Absolute Idealism Hegel taught: "in order for a consciousness to comprehend any perceived material “object”, subject must realize the essential identity of subject and object... Though both are superficially different particulars, the ...
Logicism Gottlob Frege - Mathematics is reducible to logic, and hence nothing but a part of logic.