Solipsism

Solipsism is the philosophical idea that one's own mind is all that exists. Solipsism is an epistemological or ontological position that knowledge of anything outside the mind is unjustified. The external world and other minds cannot be known and might not exist. In the history of philosophy, solipsism has served as a skeptical hypothesis.

Explanation

Denial of materialist existence, in itself, does not constitute solipsism. Possibly the most controversial feature of the solipsistic worldview is the denial of the existence of other minds. Since qualia, or personal experiences, are private and ineffable, another being's experience can be known only by analogy.

Philosophers try to build knowledge on more than an inference or analogy. The failure of Descartes' epistemological enterprise brought to popularity the idea that all certain knowledge may end at "I am thinking; therefore I am" (cogito ergo sum).^[1]

The theory of solipsism also merits close examination because it relates to three widely held philosophical presuppositions, which are themselves fundamental and wide-ranging in importance. These are that:

1. My most certain knowledge is the content of my own mind—my thoughts, experiences, affects, etc.;
2. There is no conceptual or logically necessary link between mental and physical—between, say, the occurrence of certain conscious experience or mental states and the 'possession' and behavioral dispositions of a 'body' of a particular kind (see the brain in a vat); and
3. The experience of a given person is necessarily private to that person.

Solipsism is not a single concept but instead refers to several worldviews whose common element is some form of denial of the existence of a universe independent from the mind of the agent.

History

Gorgias (of Leontini)

Solipsism is first recorded with the Greek presocratic sophist, Gorgias (c. 483–375 BC) who is quoted by the Roman skeptic Sextus Empiricus as having stated:

1. Nothing exists;
2. Even if something exists, nothing can be known about it; and
3. Even if something could be known about it, knowledge about it can't be communicated to others.

This can be expressed as:

It's always known that I exist for “my mind is the only thing I know exists”. Someone could be dreaming up a thought of me having a thought, but only I know my thoughts. And for my thoughts, I don't know of any other thoughts from anyone else and if they even control their own.

Much of the point of the Sophists was to show that "objective" knowledge was a literal impossibility. (See also comments credited to Protagoras of Abdera). The influence of the Sophists has been severely downplayed; however, modern linguistic philosophy clearly seems to have its roots in the teachings of the Sophists.

Descartes

René Descartes. Portrait by Frans Hals, 1648.

The foundations of solipsism are in turn the foundations of the view that the individual's understanding of any and all psychological concepts (thinking, willing, perceiving, etc.) is accomplished by making analogy with his or her own mental states; i.e., by abstraction from inner experience. And this view, or some variant of it, has been influential in philosophy since Descartes elevated the search for incontrovertible certainty to the status of the primary goal of epistemology, whilst also elevating epistemology to "first philosophy".