Epistemological Solipsism

philosophy

Definition

Epistemological Solipsism

Epistemological solipsism is the weakest form of solipsism. It holds that the external world and other minds may exist, but that their existence cannot be justified from the contents $M_S$ of one’s own mind alone.

Formally, for a subject $S$ with mental contents $M_S$, epistemological solipsism is the claim

$$\forall x\notin M_S:S\text{ cannot justify }┌x\text{ exists}┐.$$

It is a thesis about the limits of perception and inference, not about what exists.

Contrast with the Stronger Variant

Unlike metaphysical solipsism, epistemological solipsism does not deny the external world. It denies only that $S$ can rule out being mistaken about it. The gap is epistemic: the world may be there, but $M_S$ underdetermines whether it is.