The Simulation Hypothesis proposes that conscious beings could be immersed within an artificial Universe embedded within a higher order of reality. The roots of this argument can be found throughout the history of philosophy in such works as Plato's "Allegory of the Cave" and Descartes "evil demon".
The important distinction between these and modern Simulation Arguments has been the addition of proposed methods of engineering Simulated Reality through the use of computers and the assumption that the conscious beings themselves are simulated, rather than merely "brains in a vat". This version also suggests that it is far more likely that we are living in a Simulation than we are not.
John Barrow has suggested that if we are living in a computer simulation we may observe "glitches" in the our programmed environment due to the level of detail being compromised to save computing power. Alternatively, the Simulators may not have a full understanding of the Laws of Nature which would mean over time the simulated environment would drift away from its stable state. These "glitches" could be identified by scientists scrutinizing nature using unusual methods of observation.
- Barrow, John (2008) Living in a Simulated Universe Universe or Multiverse? ed. Bernard Carr (Cambridge University Press): pp. 481-486.