---
title: "Skepticism · Library · Simulation Hypothesis"
url: https://simulation-hypothesis.com/library/skepticism
description: "Skepticism is any philosophical position that denies we can know things, or certain kinds of things."
license: https://creativecommons.org/licenses/by/4.0/
credit: "Ross Allan Dahl, Simulation Hypothesis (simulation-hypothesis.com)"
---

## Epistemology & reality

# Skepticism

Definition

Skepticism is any philosophical position that denies we can know things, or certain kinds of things. Radical skepticism doubts that the outside world exists.

On this site

The opening question of the site. Neither answer is graded.

Role in the model

Your Reality is a skeptic’s tool. Ten answers describe a reality, and none of them is marked right or wrong. The human-cost scores beside each answer are the author’s judgement, not a grade.

Related

[Descartes’ demon](https://simulation-hypothesis.com/library/evil-demon)[Brain in a vat](https://simulation-hypothesis.com/library/brain-in-a-vat)[Epistemology](https://simulation-hypothesis.com/library/epistemology)

## The people behind the terms

14 short pages, one per thinker, each with its matching dial. See also the [reading list](https://simulation-hypothesis.com/reading).

[Plato’s cave](https://simulation-hypothesis.com/thinkers/plato)[Zhuangzi’s butterfly](https://simulation-hypothesis.com/thinkers/zhuangzi)[Vasubandhu’s dream](https://simulation-hypothesis.com/thinkers/vasubandhu)[Shankara’s māyā](https://simulation-hypothesis.com/thinkers/shankara)[al-Ghazali’s doubt](https://simulation-hypothesis.com/thinkers/ghazali)[Ibn Arabi’s imagination](https://simulation-hypothesis.com/thinkers/ibn-arabi)[Calderón’s life is a dream](https://simulation-hypothesis.com/thinkers/calderon)[Descartes’ demon](https://simulation-hypothesis.com/thinkers/descartes)[Berkeley’s perceiver](https://simulation-hypothesis.com/thinkers/berkeley)[Borges’ circular ruins](https://simulation-hypothesis.com/thinkers/borges)[Nozick’s experience machine](https://simulation-hypothesis.com/thinkers/nozick)[Putnam’s brain in a vat](https://simulation-hypothesis.com/thinkers/putnam)[Bostrom’s trilemma](https://simulation-hypothesis.com/thinkers/bostrom)[Chalmers: virtual worlds are real](https://simulation-hypothesis.com/thinkers/chalmers)