thought experiment A thought experiment is a hypothetical situation in which a hypothesis, theory, or principle is laid out for the purpose of thinking through its consequences. History The ancient Greek ''deiknymi'' (), or thought experiment, "was the most anci ...

s, philosophers and scientists occasionally imagine entities with special abilities as a way to pose tough intellectual challenges or highlight apparent

paradox A paradox is a logically self-contradictory statement or a statement that runs contrary to one's expectation. It is a statement that, despite apparently valid reasoning from true premises, leads to a seemingly self-contradictory or a logically u ...

es. Examples include: * Descartes’ malicious demon – Cartesian skepticism (also called methodological skepticism) advocates the doubting of all things that cannot be justified through logic. Descartes uses three arguments to cast doubt on our ability to know objectively: the

dream argument The dream argument is the postulation that the act of dreaming provides preliminary evidence that the senses we trust to distinguish reality from illusion should not be fully trusted, and therefore, any state that is dependent on our senses should ...

, the deceiving God argument, and the malicious demon argument. Since our senses cannot put us in contact with external objects themselves, but only with our mental images of such objects, we can have no absolute certainty that anything exists in the external world. In the evil demon argument Descartes proposes an entity who is capable of deceiving us to such a degree that we have reason to doubt the totality of what our senses tell us. *

Laplace's demon In the history of science, Laplace's demon was a notable published articulation of causal determinism on a scientific basis by Pierre-Simon Laplace in 1814. According to determinism, if someone (the demon) knows the precise location and momentu ...

is a hypothetical all-knowing being who knows the precise location and momentum of every atom in the universe, and therefore could use

Newton's laws Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows: # A body remains at rest, or in motion ...

to reveal the entire course of cosmic events, past and future. Based upon the philosophical proposition of

causal determinism Determinism is a philosophical view, where all events are determined completely by previously existing causes. Deterministic theories throughout the history of philosophy have developed from diverse and sometimes overlapping motives and consi ...

. *

Maxwell's demon Maxwell's demon is a thought experiment that would hypothetically violate the second law of thermodynamics. It was proposed by the physicist James Clerk Maxwell in 1867. In his first letter Maxwell called the demon a "finite being", while the ' ...

can distinguish between fast and slow moving molecules. If this demon only let fast moving molecules through a trapdoor to a container, the temperature inside the container would increase without any work being applied. Such a scenario violates the

second law of thermodynamics The second law of thermodynamics is a physical law based on universal experience concerning heat and Energy transformation, energy interconversions. One simple statement of the law is that heat always moves from hotter objects to colder objects ( ...

. * Morton's demon stands at the gateway of a person's senses and lets in facts that agree with that person's beliefs while deflecting those that do not. This demon is used to explain the phenomenon of

confirmation bias Confirmation bias is the tendency to search for, interpret, favor, and recall information in a way that confirms or supports one's prior beliefs or values. People display this bias when they select information that supports their views, ignoring ...

. * In aphorism 341 of

The Gay Science ''The Gay Science'' (german: Die fröhliche Wissenschaft), sometimes translated as ''The Joyful Wisdom'' or ''The Joyous Science'', is a book by Friedrich Nietzsche published in 1882, and followed by a second edition in 1887 after the completio ...

Nietzsche Friedrich Wilhelm Nietzsche (; or ; 15 October 1844 – 25 August 1900) was a German philosopher, Prose poetry, prose poet, cultural critic, Philology, philologist, and composer whose work has exerted a profound influence on contemporary philo ...

puts forth his

eternal recurrence Eternal return (german: Ewige Wiederkunft; also known as eternal recurrence) is a concept that the universe and all existence and energy has been recurring, and will continue to recur in a self similar form an infinite number of times across in ...

concept. In it, he employs a demon with special metaphysical knowledge as an agent for forcing reevaluation of perspective on one's own life. * The

Darwinian Demon A Darwinian Demon is a hypothetical organism that would result if there were no biological constraints on evolution. Such an organism would maximize all aspects of fitness simultaneously and would exist if there were no limitations from available ...

is a hypothetical organism which can simultaneously maximize all aspects of its fitness. *The demon of Bureaucratic Chaos is the phenomenon that "blocks good things from happening" at the

United States Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United Stat ...

. This hypothesized entity makes it extremely difficult to complete complex projects — by frequently changing mission requirements, funding, and strategic direction. Examples include the

Mirror Fusion Test Facility The Mirror Fusion Test Facility, or MFTF, was an experimental magnetic confinement fusion device built using the tandem magnetic mirror design. It was, by far, the largest, most powerful and most expensive mirror machine ever constructed. Due to ...

, which was constructed but never turned on; the

Superconducting Super Collider The Superconducting Super Collider (SSC) (also nicknamed the desertron) was a particle accelerator complex under construction in the vicinity of Waxahachie, Texas. Its planned ring circumference was with an energy of 20 TeV per proton and was ...

, which cost $2 billion before its cancellation; and

ITER ITER (initially the International Thermonuclear Experimental Reactor, ''iter'' meaning "the way" or "the path" in Latin) is an international nuclear fusion research and engineering megaproject aimed at creating energy by replicating, on Earth ...

, the international fusion experiment in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

that the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

has alternately supported and opposed, and to which it has threatened withdrawal, cut funding, and increased funding over the decades.

Similar entities

There are other creatures which feature in thought experiments about philosophy. One such creature is a

utility monster The utility monster is a thought experiment in the study of ethics created by philosopher Robert Nozick in 1974 as a criticism of utilitarianism. The thought experiment A hypothetical being, which Nozick calls the ''utility monster,'' receives m ...

, a creature which derives much more utility (such as enjoyment) from resources than other beings, and hence under a strict utilitarian system would have more or all of the available resources directed to it.

Newcomb's paradox In philosophy and mathematics, Newcomb's paradox, also known as Newcomb's problem, is a thought experiment involving a game between two players, one of whom is able to predict the future. Newcomb's paradox was created by William Newcomb of the Uni ...

supposes a being who is believed to be capable of predicting human behavior;

Robert Nozick Robert Nozick (; November 16, 1938 – January 23, 2002) was an American philosopher. He held the Joseph Pellegrino University Professorship at Harvard University,

References

{{reflist Thought experiments Fictional demons and devils