Thought experiment

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Schrodinger's cat (1935) presents a cat that is in a superposition of alive and dead states, depending on a random quantum event. It illustrates the counter-intuitive implications of Bohr's Copenhagen interpretation when applied to everyday objects. Schrodingers cat.svg
Schrödinger's cat (1935) presents a cat that is in a superposition of alive and dead states, depending on a random quantum event. It illustrates the counter-intuitive implications of Bohr's Copenhagen interpretation when applied to everyday objects.

A thought experiment is a hypothetical situation in which a hypothesis, theory, [lower-alpha 1] or principle is laid out for the purpose of thinking through its consequences. The concept is also referred to as a Gedankenexperiment within the work of Ernst Mach [2] and includes thoughts about what may have occurred if a different course of action were taken as opposed to what did in fact occur. [3] [4] The importance of this ability is that it allows us to imagine what may occur in the future, as well as the implication of alternate courses of action. [5] [6]



The ancient Greek δείκνυμι, deiknymi, 'thought experiment', "was the most ancient pattern of mathematical proof", and existed before Euclidean mathematics, [7] where the emphasis was on the conceptual, rather than on the experimental part of a thought-experiment.

Johann Witt-Hansen established that Hans Christian Ørsted was the first to use the term Gedankenexperiment (from German: 'thought experiment') circa 1812. [8] [9] Ørsted was also the first to use the equivalent term Gedankenversuch in 1820.

By 1883, Ernst Mach used the term Gedankenexperiment in a different way, to denote exclusively the imaginary conduct of a real experiment that would be subsequently performed as a real physical experiment by his students. [10] Physical and mental experimentation could then be contrasted: Mach asked his students to provide him with explanations whenever the results from their subsequent, real, physical experiment differed from those of their prior, imaginary experiment.

The English term thought experiment was coined (as a calque) from Mach's Gedankenexperiment, and it first appeared in the 1897 English translation of one of Mach's papers. [11] Prior to its emergence, the activity of posing hypothetical questions that employed subjunctive reasoning had existed for a very long time (for both scientists and philosophers). The irrealis moods are ways to categorize it or to speak about it. This helps explain the extremely wide and diverse range of the application of the term "thought experiment" once it had been introduced into English.

Galileo's thought experiment concerned the outcome (c) of attaching a small stone (a) to a larger one (b). Thought-experiment-free-falling-bodies.svg
Galileo's thought experiment concerned the outcome (c) of attaching a small stone (a) to a larger one (b).

Galileo's demonstration that falling objects must fall at the same rate regardless of their masses was a significant step forward in the history of modern science. This is widely thought [12] to have been a straightforward physical demonstration, involving climbing up the Leaning Tower of Pisa and dropping two heavy weights off it, whereas in fact, it was a logical demonstration, using the 'thought experiment' technique. The 'experiment' is described by Galileo in Discorsi e dimostrazioni matematiche (1638) (from Italian: 'Mathematical Discourses and Demonstrations') thus:

Salviati. If then we take two bodies whose natural speeds are different, it is clear that on uniting the two, the more rapid one will be partly retarded by the slower, and the slower will be somewhat hastened by the swifter. Do you not agree with me in this opinion?

Simplicio. You are unquestionably right.

Salviati. But if this is true, and if a large stone moves with a speed of, say, eight while a smaller moves with a speed of four, then when they are united, the system will move with a speed less than eight; but the two stones when tied together make a stone larger than that which before moved with a speed of eight. Hence the heavier body moves with less speed than the lighter; an effect which is contrary to your supposition. Thus you see how, from your assumption that the heavier body moves more rapidly than the lighter one, I infer that the heavier body moves more slowly. [13]


The common goal of a thought experiment is to explore the potential consequences of the principle in question:

A thought experiment is a device with which one performs an intentional, structured process of intellectual deliberation in order to speculate, within a specifiable problem domain, about potential consequents (or antecedents) for a designated antecedent (or consequent). [14]

Given the structure of the experiment, it may not be possible to perform it, and even if it could be performed, there need not be an intention to perform it.

Examples of thought experiments include Schrödinger's cat, illustrating quantum indeterminacy through the manipulation of a perfectly sealed environment and a tiny bit of radioactive substance, and Maxwell's demon, which attempts to demonstrate the ability of a hypothetical finite being to violate the 2nd law of thermodynamics.

It is a common element of science-fiction stories. [15]

Thought experiments, which are well-structured, well-defined hypothetical questions that employ subjunctive reasoning (irrealis moods) – "What might happen (or, what might have happened) if . . . " – have been used to pose questions in philosophy at least since Greek antiquity, some pre-dating Socrates. [16] In physics and other sciences many thought experiments date from the 19th and especially the 20th Century, but examples can be found at least as early as Galileo.

In thought experiments, we gain new information by rearranging or reorganizing already known empirical data in a new way and drawing new (a priori) inferences from them or by looking at these data from a different and unusual perspective. In Galileo's thought experiment, for example, the rearrangement of empirical experience consists of the original idea of combining bodies of different weights. [17]

Thought experiments have been used in philosophy (especially ethics), physics, and other fields (such as cognitive psychology, history, political science, economics, social psychology, law, organizational studies, marketing, and epidemiology). In law, the synonym "hypothetical" is frequently used for such experiments.

Regardless of their intended goal, all thought experiments display a patterned way of thinking that is designed to allow us to explain, predict and control events in a better and more productive way.

Theoretical consequences

In terms of their theoretical consequences, thought experiments generally:

Practical applications

Thought experiments can produce some very important and different outlooks on previously unknown or unaccepted theories. However, they may make those theories themselves irrelevant, and could possibly create new problems that are just as difficult, or possibly more difficult to resolve.

In terms of their practical application, thought experiments are generally created to:


Temporal representation of a prefactual thought experiment The Prefactual Thought Experiment.jpg
Temporal representation of a prefactual thought experiment

Generally speaking, there are seven types of thought experiments in which one reasons from causes to effects, or effects to causes: [19] [20]


Prefactual (before the fact) thought experiments – the term prefactual was coined by Lawrence J. Sanna in 1998 [21] – speculate on possible future outcomes, given the present, and ask "What will be the outcome if event E occurs?". [22] [23]


Temporal representation of a counterfactual thought experiment The Counterfactual Thought Experiment.jpg
Temporal representation of a counterfactual thought experiment

Counterfactual (contrary to established fact) thought experiments – the term counterfactual was coined by Nelson Goodman in 1947, [25] extending Roderick Chisholm's (1946) notion of a "contrary-to-fact conditional" [26] – speculate on the possible outcomes of a different past; [27] and ask "What might have happened if A had happened instead of B?" (e.g., "If Isaac Newton and Gottfried Leibniz had cooperated with each other, what would mathematics look like today?"). [28] [29] [23]

The study of counterfactual speculation has increasingly engaged the interest of scholars in a wide range of domains such as philosophy, [30] psychology, [31] cognitive psychology, [32] history, [33] political science, [34] economics, [35] social psychology, [36] law, [37] organizational theory, [38] marketing, [39] and epidemiology. [40]


Temporal representation of a semifactual thought experiment The Semifactual Thought Experiment.jpg
Temporal representation of a semifactual thought experiment

Semifactual thought experiments – the term semifactual was coined by Nelson Goodman in 1947 [25] [41] – speculate on the extent to which things might have remained the same, despite there being a different past; and asks the question Even though X happened instead of E, would Y have still occurred? (e.g., Even if the goalie had moved left, rather than right, could he have intercepted a ball that was traveling at such a speed?). [42] [23]

Semifactual speculations are an important part of clinical medicine.


Temporal representation of prediction, forecasting and nowcasting Prediction, Forecasting and Nowcasting.jpg
Temporal representation of prediction, forecasting and nowcasting

The activity of prediction attempts to project the circumstances of the present into the future. [44] [45] According to David Sarewitz and Roger Pielke (1999, p123), scientific prediction takes two forms:

  1. "The elucidation of invariant – and therefore predictive – principles of nature"; and
  2. "[Using] suites of observational data and sophisticated numerical models in an effort to foretell the behavior or evolution of complex phenomena". [46]

Although they perform different social and scientific functions, the only difference between the qualitatively identical activities of predicting, forecasting, and nowcasting is the distance of the speculated future from the present moment occupied by the user. [47] Whilst the activity of nowcasting, defined as "a detailed description of the current weather along with forecasts obtained by extrapolation up to 2 hours ahead", is essentially concerned with describing the current state of affairs, it is common practice to extend the term "to cover very-short-range forecasting up to 12 hours ahead" (Browning, 1982, p.ix). [48] [49]


Temporal representation of hindcasting Hindcasting.jpeg
Temporal representation of hindcasting

The activity of hindcasting involves running a forecast model after an event has happened in order to test whether the model's simulation is valid. [44] [45]


Temporal representation of retrodiction or postdiction Retrodiction or Postdiction.jpg
Temporal representation of retrodiction or postdiction

The activity of retrodiction (or postdiction) involves moving backward in time, step-by-step, in as many stages as are considered necessary, from the present into the speculated past to establish the ultimate cause of a specific event (e.g., reverse engineering and forensics). [51] [45]

Given that retrodiction is a process in which "past observations, events, add and data are used as evidence to infer the process(es) that produced them" and that diagnosis "involve[s] going from visible effects such as symptoms, signs and the like to their prior causes", [52] the essential balance between prediction and retrodiction could be characterized as:

retrodiction : diagnosis :: prediction : prognosis

regardless of whether the prognosis is of the course of the disease in the absence of treatment, or of the application of a specific treatment regimen to a specific disorder in a particular patient. [53]


Temporal representation of backcasting Backcasting.jpg
Temporal representation of backcasting

The activity of backcasting – the term backcasting was coined by John Robinson in 1982 [55] – involves establishing the description of a very definite and very specific future situation. It then involves an imaginary moving backward in time, step-by-step, in as many stages as are considered necessary, from the future to the present to reveal the mechanism through which that particular specified future could be attained from the present. [56] [57] [58]

Backcasting is not concerned with predicting the future:

The major distinguishing characteristic of backcasting analyses is the concern, not with likely energy futures, but with how desirable futures can be attained. It is thus explicitly normative, involving 'working backward' from a particular future end-point to the present to determine what policy measures would be required to reach that future. [59]

According to Jansen (1994, p. 503: [60]

Within the framework of technological development, "forecasting" concerns the extrapolation of developments towards the future and the exploration of achievements that can be realized through technology in the long term. Conversely, the reasoning behind "backcasting" is: on the basis of an interconnecting picture of demands technology must meet in the future – "sustainability criteria" – to direct and determine the process that technology development must take and possibly also the pace at which this development process must take effect. Backcasting [is] both an important aid in determining the direction technology development must take and in specifying the targets to be set for this purpose. As such, backcasting is an ideal search toward determining the nature and scope of the technological challenge posed by sustainable development, and it can thus serve to direct the search process toward new – sustainable – technology.


Thought experiments have been used in a variety of fields, including philosophy, law, physics, and mathematics. In philosophy they have been used at least since classical antiquity, some pre-dating Socrates. In law, they were well known to Roman lawyers quoted in the Digest. [61] In physics and other sciences, notable thought experiments date from the 19th and, especially, the 20th century; but examples can be found at least as early as Galileo.


In philosophy, a thought experiment typically presents an imagined scenario with the intention of eliciting an intuitive or reasoned response about the way things are in the thought experiment. (Philosophers might also supplement their thought experiments with theoretical reasoning designed to support the desired intuitive response.) The scenario will typically be designed to target a particular philosophical notion, such as morality, or the nature of the mind or linguistic reference. The response to the imagined scenario is supposed to tell us about the nature of that notion in any scenario, real or imagined.

For example, a thought experiment might present a situation in which an agent intentionally kills an innocent for the benefit of others. Here, the relevant question is not whether the action is moral or not, but more broadly whether a moral theory is correct that says morality is determined solely by an action's consequences (See Consequentialism). John Searle imagines a man in a locked room who receives written sentences in Chinese, and returns written sentences in Chinese, according to a sophisticated instruction manual. Here, the relevant question is not whether or not the man understands Chinese, but more broadly, whether a functionalist theory of mind is correct.

It is generally hoped that there is universal agreement about the intuitions that a thought experiment elicits. (Hence, in assessing their own thought experiments, philosophers may appeal to "what we should say," or some such locution.) A successful thought experiment will be one in which intuitions about it are widely shared. But often, philosophers differ in their intuitions about the scenario.

Other philosophical uses of imagined scenarios arguably are thought experiments also. In one use of scenarios, philosophers might imagine persons in a particular situation (maybe ourselves), and ask what they would do.

For example, in the veil of ignorance, John Rawls asks us to imagine a group of persons in a situation where they know nothing about themselves, and are charged with devising a social or political organization. The use of the state of nature to imagine the origins of government, as by Thomas Hobbes and John Locke, may also be considered a thought experiment. Søren Kierkegaard explored the possible ethical and religious implications of Abraham's binding of Isaac in Fear and Trembling . Similarly, Friedrich Nietzsche, in On the Genealogy of Morals , speculated about the historical development of Judeo-Christian morality, with the intent of questioning its legitimacy.

An early written thought experiment was Plato's allegory of the cave. [62] Another historic thought experiment was Avicenna's "Floating Man" thought experiment in the 11th century. He asked his readers to imagine themselves suspended in the air isolated from all sensations in order to demonstrate human self-awareness and self-consciousness, and the substantiality of the soul. [63]


Scientists tend to use thought experiments as imaginary, "proxy" experiments prior to a real, "physical" experiment (Ernst Mach always argued that these gedankenexperiments were "a necessary precondition for physical experiment"). In these cases, the result of the "proxy" experiment will often be so clear that there will be no need to conduct a physical experiment at all.

Scientists also use thought experiments when particular physical experiments are impossible to conduct (Carl Gustav Hempel labeled these sorts of experiment "theoretical experiments-in-imagination"), such as Einstein's thought experiment of chasing a light beam, leading to special relativity. This is a unique use of a scientific thought experiment, in that it was never carried out, but led to a successful theory, proven by other empirical means.


Further categorization of thought experiments can be attributed to specific properties.


In many thought experiments, the scenario would be nomologically possible, or possible according to the laws of nature. John Searle's Chinese room is nomologically possible.

Some thought experiments present scenarios that are not nomologically possible. In his Twin Earth thought experiment, Hilary Putnam asks us to imagine a scenario in which there is a substance with all of the observable properties of water (e.g., taste, color, boiling point), but is chemically different from water. It has been argued that this thought experiment is not nomologically possible, although it may be possible in some other sense, such as metaphysical possibility. It is debatable whether the nomological impossibility of a thought experiment renders intuitions about it moot.

In some cases, the hypothetical scenario might be considered metaphysically impossible, or impossible in any sense at all. David Chalmers says that we can imagine that there are zombies, or persons who are physically identical to us in every way but who lack consciousness. This is supposed to show that physicalism is false. However, some argue that zombies are inconceivable: we can no more imagine a zombie than we can imagine that 1+1=3. Others have claimed that the conceivability of a scenario may not entail its possibility.

Causal reasoning

The first characteristic pattern that thought experiments display is their orientation in time. [64] They are either:

The second characteristic pattern is their movement in time in relation to "the present moment standpoint" of the individual performing the experiment; namely, in terms of:

Relation to real experiments

The relation to real experiments can be quite complex, as can be seen again from an example going back to Albert Einstein. In 1935, with two coworkers, he published a paper on a newly created subject called later the EPR effect (EPR paradox). In this paper, starting from certain philosophical assumptions, [65] on the basis of a rigorous analysis of a certain, complicated, but in the meantime assertedly realizable model, he came to the conclusion that quantum mechanics should be described as "incomplete". Niels Bohr asserted a refutation of Einstein's analysis immediately, and his view prevailed. [66] [67] [68] After some decades, it was asserted that feasible experiments could prove the error of the EPR paper. These experiments tested the Bell inequalities published in 1964 in a purely theoretical paper. The above-mentioned EPR philosophical starting assumptions were considered to be falsified by the empirical fact (e.g. by the optical real experiments of Alain Aspect).

Thus thought experiments belong to a theoretical discipline, usually to theoretical physics, but often to theoretical philosophy. In any case, it must be distinguished from a real experiment, which belongs naturally to the experimental discipline and has "the final decision on true or not true", at least in physics.


Thought experiments can also be interactive where the author invites people into his thought process through providing alternative paths with alternative outcomes within the narrative, or through interaction with a programmed machine, like a computer program.

Thanks to the advent of the Internet, the digital space has lent itself as a new medium for a new kind of thought experiments. The philosophical work of Stefano Gualeni, for example, focuses on the use of virtual worlds to materialize thought experiments and to playfully negotiate philosophical ideas. [69] His arguments were originally presented in his book Virtual Worlds as Philosophical Tools.

Gualeni's argument is that the history of philosophy has, until recently, merely been the history of written thought, and digital media can complement and enrich the limited and almost exclusively linguistic approach to philosophical thought. [69] [70] He considers virtual worlds to be philosophically viable and advantageous in contexts like those of thought experiments, when the recipients of a certain philosophical notion or perspective are expected to objectively test and evaluate different possible courses of action, or in cases where they are confronted with interrogatives concerning non-actual or non-human phenomenologies. [69] [70]







Computer science


See also


  1. "[C]onjectures or hypotheses ... are really to be regarded as thought "experiments" through which we wish to discover whether something can be explained by a specific assumption in connection with other natural laws." Hans Christian Ørsted ("First Introduction to General Physics" ¶16-¶18, part of a series of public lectures at the University of Copenhagen. Copenhagen 1811, in Danish, printed by Johan Frederik Schulz. In Kirstine Meyer's 1920 edition of Ørsted's works, vol.III pp. 151–190.) "First Introduction to Physics: the Spirit, Meaning, and Goal of Natural Science". Reprinted in German in 1822, Schweigger's Journal für Chemie und Physik36, pp. 458–488, as translated in Ørsted 1997, pp. 296–298

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Cognitive psychology is the scientific study of mental processes such as attention, language use, memory, perception, problem solving, creativity, and reasoning.

In its most common sense, philosophical methodology is the field of inquiry studying the methods used to do philosophy. But the term can also refer to the methods themselves. It may be understood in a wide sense as the general study of principles used for theory selection, or in a more narrow sense as the study of ways of conducting one's research and theorizing with the goal of acquiring philosophical knowledge. Philosophical methodology investigates both descriptive issues, such as which methods actually have been used by philosophers, and normative issues, such as which methods should be used or how to do good philosophy.

In quantum mechanics, counterfactual definiteness (CFD) is the ability to speak "meaningfully" of the definiteness of the results of measurements that have not been performed. The term "counterfactual definiteness" is used in discussions of physics calculations, especially those related to the phenomenon called quantum entanglement and those related to the Bell inequalities. In such discussions "meaningfully" means the ability to treat these unmeasured results on an equal footing with measured results in statistical calculations. It is this aspect of counterfactual definiteness that is of direct relevance to physics and mathematical models of physical systems and not philosophical concerns regarding the meaning of unmeasured results.

<span class="mw-page-title-main">Thought</span> Cognitive process independent of the senses

In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, and deliberation. But other mental processes, like considering an idea, memory, or imagination, are also often included. These processes can happen internally independent of the sensory organs, unlike perception. But when understood in the widest sense, any mental event may be understood as a form of thinking, including perception and unconscious mental processes. In a slightly different sense, the term thought refers not to the mental processes themselves but to mental states or systems of ideas brought about by these processes.

Reason is the capacity of applying logic consciously by drawing conclusions from new or existing information, with the aim of seeking the truth. It is associated with such characteristically human activities as philosophy, religion, science, language, mathematics, and art, and is normally considered to be a distinguishing ability possessed by humans. Reason is sometimes referred to as rationality.

Quantum suicide is a thought experiment in quantum mechanics and the philosophy of physics. Purportedly, it can falsify any interpretation of quantum mechanics other than the Everett many-worlds interpretation by means of a variation of the Schrödinger's cat thought experiment, from the cat's point of view. Quantum immortality refers to the subjective experience of surviving quantum suicide. This concept is sometimes conjectured to be applicable to real-world causes of death as well.

Eliminative materialism is a materialist position in the philosophy of mind. It is the idea that the majority of mental states in folk psychology do not exist. Some supporters of eliminativism argue that no coherent neural basis will be found for many everyday psychological concepts such as belief or desire, since they are poorly defined. The argument is that psychological concepts of behavior and experience should be judged by how well they reduce to the biological level. Other versions entail the nonexistence of conscious mental states such as pain and visual perceptions.

A philosophical zombie is a being in a thought experiment in philosophy of mind that is physically identical to a normal human being but does not have conscious experience.

<span class="mw-page-title-main">Mental model</span> Way of representing external reality within ones mind

A mental model is an internal representation (model) of external reality: that is, a way of representing reality within one's mind. Such models are hypothesized to play a major role in cognition, reasoning and decision-making. The term for this concept was coined in 1943 by Kenneth Craik, who suggested that the mind constructs "small-scale models" of reality that it uses to anticipate events.

Retrodiction is the act of making a prediction about the past. It is also known as postdiction.

In moral psychology, social intuitionism is a model that proposes that moral positions are often non-verbal and behavioral. Often such social intuitionism is based on "moral dumbfounding" where people have strong moral reactions but fail to establish any kind of rational principle to explain their reaction.

Niall Shanks was an English philosopher and critic of intelligent design.

Backcasting is a planning method that starts with defining a desirable future and then works backwards to identify policies and programs that will connect that specified future to the present. The fundamentals of the method were outlined by John B. Robinson from the University of Waterloo in 1990. The fundamental question of backcasting asks: "if we want to attain a certain goal, what actions must be taken to get there?"

<span class="mw-page-title-main">Outline of thought</span> Overview of and topical guide to thought

The following outline is provided as an overview of and topical guide to thought (thinking):

Counterfactual thinking is a concept in psychology that involves the human tendency to create possible alternatives to life events that have already occurred; something that is contrary to what actually happened. Counterfactual thinking is, as it states: "counter to the facts". These thoughts consist of the "What if?" and the "If only..." that occur when thinking of how things could have turned out differently. Counterfactual thoughts include things that – in the present – could not have happened because they are dependent on events that did not occur in the past.

<span class="mw-page-title-main">Theoretical physics</span> Branch of physics

Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena.

<i>The Conscious Mind</i> 1996 philosophy book by David Chalmers

The Conscious Mind: In Search of a Fundamental Theory was published in 1996, and is the first book written by David Chalmers, an Australian philosopher specialising in philosophy of mind. Although the book has been greatly influential, Chalmers maintains that it is "far from perfect", as most of it was written as part of his PhD dissertation after "studying philosophy for only four years".

John L. Pollock (1940–2009) was an American philosopher known for influential work in epistemology, philosophical logic, cognitive science, and artificial intelligence.

An index list of articles about the philosophy of science.

Defensive pessimism is a cognitive strategy in which an individual sets a low expectation for their performance, regardless of how well they have done in the past. Individuals use defensive pessimism as a strategy to prepare for anxiety-provoking events or performances. Defensive pessimists then think through specific negative events and setbacks that could adversely influence their goal pursuits. By envisioning possible negative outcomes, defensive pessimists can take action to avoid or prepare for them. Using this strategy, defensive pessimists can advantageously harness anxiety that might otherwise harm their performance.


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  19. Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). p. 138-159.
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  23. 1 2 3 Also, see Garbey, Joerger & Furr (2023), pp. 112, 126.
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  28. In 1748, when defining causation, David Hume referred to a counterfactual case: "…we may define a cause to be an object, followed by another, and where all objects, similar to the first, are followed by objects similar to the second. Or in other words, where, if the first object had not been, the second never had existed …" (Hume, D. (Beauchamp, T.L., ed.), An Enquiry Concerning Human Understanding, Oxford University Press, (Oxford), 1999, (7), p. 146.)
  29. See Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). pp.  139–140, 141–142, 143–144.
  30. Goodman, N., "The Problem of Counterfactual Conditionals", The Journal of Philosophy, Vol.44, No.5, (27 February 1947), pp. 113–128; Brown, R, & Watling, J., "Counterfactual Conditionals", Mind, Vol.61, No.242, (April 1952), pp. 222–233; Parry, W.T., "Reëxamination of the Problem of Counterfactual Conditionals", The Journal of Philosophy, Vol.54, No.4, (14 February 1957), pp. 85–94; Cooley, J.C., "Professor Goodman's Fact, Fiction, & Forecast", The Journal of Philosophy, Vol.54, No.10, (9 May 1957), pp. 293–311; Goodman, N., "Parry on Counterfactuals", The Journal of Philosophy, Vol.54, No.14, (4 July 1957), pp. 442–445; Goodman, N., "Reply to an Adverse Ally", The Journal of Philosophy, Vol.54, No.17, (15 August 1957), pp. 531–535; Lewis, D., Counterfactuals, Basil Blackwell, (Oxford), 1973, etc.
  31. Fillenbaum, S., "Information Amplified: Memory for Counterfactual Conditionals", Journal of Experimental Psychology, Vol.102, No.1, (January 1974), pp. 44–49; Crawford, M.T. & McCrea, S.M., "When Mutations meet Motivations: Attitude Biases in Counterfactual Thought", Journal of Experimental Social Psychology, Vol.40, No.1, (January 2004), pp. 65–74, etc.
  32. Kahneman, D. & Tversky, A., "The Simulation Heuristic", pp. 201–208 in Kahneman, D., Slovic, P. & Tversky, A. (eds), Judgement Under Uncertainty: Heuristics and Biases, Cambridge University Press, (Cambridge), 1982; Sherman, S.J. & McConnell, A.R., "Dysfunctional Implications of Counterfactual Thinking: When Alternatives to reality Fail Us", pp. 199–231 in Roese, N.J. & Olson, J.M. (eds.), What Might Have Been: The Social Psychology of Counterfactual Thinking, Lawrence Erlbaum Associates, (Mahwah), 1995;Nasco, S.A. & Marsh, K.L., "Gaining Control Through Counterfactual Thinking", Personality and Social Psychology Bulletin, Vol.25, No.5, (May 1999), pp. 556–568; McCloy, R. & Byrne, R.M.J., "Counterfactual Thinking About Controllable Events", Memory and Cognition, Vol.28, No.6, (September 2000), pp. 1071–1078; Byrne, R.M.J., "Mental Models and Counterfactual Thoughts About What Might Have Been", Trends in Cognitive Sciences, Vol.6, No.10, (October 2002), pp. 426–431; Thompson, V.A. & Byrne, R.M.J., "Reasoning Counterfactually: Making Inferences About Things That Didn't Happen", Journal of Experimental Psychology: Learning, Memory, and Cognition, Vol.28, No.6, (November 2002), pp. 1154–1170, etc.
  33. Greenberg, M. (ed.), The Way It Wasn't: Great Science Fiction Stories of Alternate History, Citadel Twilight, (New York), 1996; Dozois, G. & Schmidt, W. (eds.), Roads Not Taken: Tales of Alternative History, The Ballantine Publishing Group, (New York), 1998; Sylvan, D. & Majeski, S., "A Methodology for the Study of Historical Counterfactuals", International Studies Quarterly, Vol.42, No.1, (March 1998), pp. 79–108; Ferguson, N., (ed.), Virtual History: Alternatives and Counterfactuals, Basic Books, (New York), 1999; Cowley, R. (ed.), What If?: The World's Foremost Military Historians Imagine What Might have Been, Berkley Books, (New York), 2000; Cowley, R. (ed.), What If? 2: Eminent Historians Imagine What Might have Been, G.P. Putnam's Sons, (New York), 2001, etc.
  34. Fearon, J.D., "Counterfactuals and Hypothesis Testing in Political Science", World Politics, Vol.43, No.2, (January 1991), pp. 169–195; Tetlock, P.E. & Belkin, A. (eds.), Counterfactual Thought Experiments in World Politics, Princeton University Press, (Princeton), 1996; Lebow, R.N., "What's so Different about a Counterfactual?", World Politics, Vol.52, No.4, (July 2000), pp. 550–585; Chwieroth, J.M., "Counterfactuals and the Study of the American Presidency", Presidential Studies Quarterly, Vol.32, No.2, (June 2002), pp. 293–327, etc.
  35. Cowan, R. & Foray, R., "Evolutionary Economics and the Counterfactual Threat: On the Nature and Role of Counterfactual History as an Empirical Tool in Economics", Journal of Evolutionary Economics, Vol.12, No.5, (December 2002), pp. 539–562, etc.
  36. Roese, N.J. & Olson, J.M. (eds.), What Might Have Been: The Social Psychology of Counterfactual Thinking, Lawrence Erlbaum Associates, (Mahwah), 1995; Sanna, L.J., "Defensive Pessimism, Optimism, and Simulating Alternatives: Some Ups and Downs of Prefactual and Counterfactual Thinking", Journal of Personality and Social Psychology, Vol.71, No.5, (November 1996), pp. 1020–1036; Roese, N.J., "Counterfactual Thinking", Psychological Bulletin, Vol.121, No.1, (January 1997), pp. 133–148; Sanna, L.J., "Defensive Pessimism and Optimism: The Bitter-Sweet Influence of Mood on Performance and Prefactual and Counterfactual Thinking", Cognition and Emotion, Vol.12, No.5, (September 1998), pp. 635–665; Sanna, L.J. & Turley-Ames, K.J., "Counterfactual Intensity", European Journal of Social Psychology, Vol.30, No.2, (March/April 2000), pp. 273–296; Sanna, L.J., Parks, C.D., Meier, S., Chang, E.C., Kassin, B.R., Lechter, J.L., Turley-Ames, K.J. & Miyake, T.M., "A Game of Inches: Spontaneous Use of Counterfactuals by Broadcasters During Major League Baseball Playoffs", Journal of Applied Social Psychology, Vol.33, No.3, (March 2003), pp. 455–475, etc.
  37. Strassfeld, R.N., "If...: Counterfactuals in the Law", George Washington Law Review, Volume 60, No.2, (January 1992), pp. 339–416; Spellman, B.A. & Kincannon, A., "The Relation between Counterfactual ("but for") and Causal reasoning: Experimental Findings and Implications for Juror's Decisions", Law and Contemporary Problems, Vol.64, No.4, (Autumn 2001), pp. 241–264; Prentice, R.A. & Koehler, J.J., "A Normality Bias in Legal Decision Making", Cornell Law Review, Vol.88, No.3, (March 2003), pp. 583–650, etc.
  38. Creyer, E.H. & Gürhan, Z., "Who's to Blame? Counterfactual Reasoning and the Assignment of Blame", Psychology and Marketing, Vol.14, No.3, (May 1997), pp. 209–307; Zeelenberg, M., van Dijk, W.W., van der Plight, J., Manstead, A.S.R., van Empelen, P., & Reinderman, D., "Emotional Reactions to the Outcomes of Decisions: The Role of Counterfactual Thought in the Experience of Regret and Disappointment", Organizational Behavior and Human Decision Processes, Vol.75, No.2, (August 1998), pp. 117–141; Naquin, C.E. & Tynan, R.O., "The Team Halo Effect: Why Teams Are Not Blamed for Their Failures", Journal of Applied Psychology, Vol.88, No.2, (April 2003), pp. 332–340; Naquin, C.E., "The Agony of Opportunity in Negotiation: Number of Negotiable Issues, Counterfactual Thinking, and Feelings of Satisfaction", Organizational Behavior and Human Decision Processes, Vol.91, No.1, (May 2003), pp. 97–107, etc.
  39. Hetts, J.J., Boninger, D.S., Armor, D.A., Gleicher, F. & Nathanson, A., "The Influence of Anticipated Counterfactual Regret on Behavior", Psychology & Marketing, Vol.17, No.4, (April 2000), pp. 345–368; Landman, J. & Petty, R., ""It Could Have Been You": How States Exploit Counterfactual Thought to Market Lotteries", Psychology & Marketing, Vol.17, No.4, (April 2000), pp. 299–321; McGill, A.L., "Counterfactual Reasoning in Causal Judgements: Implications for Marketing", Psychology & Marketing, Vol.17, No.4, (April 2000), pp. 323–343; Roese, N.J., "Counterfactual Thinking and Marketing: Introduction to the Special Issue", Psychology & Marketing', Vol.17, No.4, (April 2000), pp. 277–280; Walchli, S.B. & Landman, J., "Effects of Counterfactual Thought on Postpurchase Consumer Affect", Psychology & Marketing, Vol.20, No.1, (January 2003), pp. 23–46, etc.
  40. Randerson, J., "Fast action would have saved millions", New Scientist, Vol.176, No.2372, (7 December 2002), p. 19; Haydon, D.T., Chase-Topping, M., Shaw, D.J., Matthews, L., Friar, J.K., Wilesmith, J. & Woolhouse, M.E.J., "The Construction and Analysis of Epidemic Trees With Reference to the 2001 UK Foot-and-Mouth Outbreak", Proceedings of the Royal Society of London Series B: Biological Sciences, Vol.270, No.1511, (22 January 2003), pp. 121–127, etc.
  41. Goodman's original concept has been subsequently developed and expanded by (a) Daniel Cohen (Cohen, D., "Semifactuals, Even-Ifs, and Sufficiency", International Logic Review, Vol.16, (1985), pp. 102–111), (b) Stephen Barker (Barker, S., "Even, Still and Counterfactuals", Linguistics and Philosophy, Vol.14, No.1, (February 1991), pp. 1–38; Barker, S., "Counterfactuals, Probabilistic Counterfactuals and Causation", Mind, Vol.108, No.431, (July 1999), pp. 427–469), and (c) Rachel McCloy and Ruth Byrne (McCloy, R. & Byrne, R.M.J., "Semifactual 'Even If' Thinking", Thinking and Reasoning, Vol.8, No.1, (February 2002), pp. 41–67).
  42. See Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). pp.  139–140, 141–142, 144.
  43. 1 2 Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). p. 145.
  44. 1 2 See Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). pp.  139–140, 141–142, 145.
  45. 1 2 3 Also, see Garbey, Joerger & Furr (2023), pp. 112, 127.
  46. Sarewitz, D. & Pielke, R., "Prediction in Science and Policy", Technology in Society, Vol.21, No.2, (April 1999), pp. 121–133.
  47. Nowcasting (obviously based on forecasting) is also known as very-short-term forecasting; thus, also indicating a very-short-term, mid-range, and long-range forecasting continuum.
  48. Browning, K.A. (ed.), Nowcasting, Academic Press, (London), 1982.
  49. Murphy, and Brown – Murphy, A.H. & Brown, B.G., "Similarity and Analogical Reasoning: A Synthesis", pp. 3–15 in Browning, K.A. (ed.), Nowcasting, Academic Press, (London), 1982 – describe a large range of specific applications for meteorological nowcasting over a wide range of user demands:
    (1) Agriculture: (a) wind and precipitation forecasts for effective seeding and spraying from aircraft; (b) precipitation forecasts to minimize damage to seedlings; (c) minimum temperature, dewpoint, cloud cover, and wind speed forecasts to protect crops from frost; (d) maximum temperature forecasts to reduce adverse effects of high temperatures on crops and livestock; (e) humidity and cloud cover forecasts to prevent fungal disease crop losses; (f) hail forecasts to minimize damage to livestock and greenhouses; (g) precipitation, temperature, and dewpoint forecasts to avoid during- and after-harvest losses due to crops rotting in the field; (h) precipitation forecasts to minimize losses in drying raisins; and (i) humidity forecasts to reduce costs and losses resulting from poor conditions for drying tobacco.
    (2) Construction: (a) precipitation and wind speed forecasts to avoid damage to finished work (e.g. concrete) and minimize costs of protecting exposed surfaces, structures, and work sites; and (b) precipitation, wind speed, and high/low-temperature forecasts to schedule work in an efficient manner.
    (3) Energy: (a) temperature, humidity, wind, cloud, etc. forecasts to optimize procedures related to generation and distribution of electricity and gas; (b) forecasts of thunderstorms, strong winds, low temperatures, and freezing precipitation minimize damage to lines and equipment and to schedule repairs.
    (4) Transportation: (a) ceiling height and visibility, winds and turbulence, and surface ice and snow forecasts minimize risk, maximize efficiency in pre-flight and in-flight decisions and other adjustments to weather-related fluctuations in traffic; (b) forecasts of wind speed and direction, as well as severe weather and icing conditions along flight paths facilitate optimal airline route planning; (c) forecasts of snowfall, precipitation, and other storm-related events allow truckers, motorists, and public transportation systems to avoid damage to weather-sensitive goods, select optimum routes, prevent accidents, minimize delays, and maximize revenues under conditions of adverse weather.
    (5) Public Safety & General Public: (a) rain, snow, wind, and temperature forecasts assist the general public in planning activities such as commuting, recreation, and shopping; (b) forecasts of temperature/humidity extremes (or significant changes) alert hospitals, clinics, and the public to weather conditions that may seriously aggravate certain health-related illnesses; (c) forecasts related to potentially dangerous or damaging natural events (e.g., tornados, severe thunderstorms, severe winds, storm surges, avalanches, precipitation, floods) minimize loss of life and property damage; and (d) forecasts of snowstorms, surface icing, visibility, and other events (e.g. floods) enable highway maintenance and traffic control organizations to take appropriate actions to reduce risks of traffic accidents and protect roads from damage.
  50. Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). p. 146.
  51. See Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). pp.  139–140, 141–142, 146.
  52. p. 24, Einhorn, H.J. & Hogarth, R.M., "Prediction, Diagnosis, and Causal Thinking in Forecasting", Journal of Forecasting, (January–March 1982), Vol.1, No.1, pp. 23–36.
  53. "…We consider diagnostic inference to be based on causal thinking, although in doing diagnosis one has to mentally reverse the time order in which events were thought to have occurred (hence the term "backward inference"). On the other hand, predictions involve forward inference; i.e., one goes forward in time from present causes to future effects. However, it is important to recognize the dependence of forward inference/prediction on backward inference/diagnosis. In particular, it seems likely that success in predicting the future depends to a considerable degree on making sense of the past. Therefore, people are continually engaged in shifting between forward and backward inference in both making and evaluating forecasts. Indeed, this can be eloquently summarized by Kierkegaard's observation that 'Life can only be understood backward; but it must be lived forwards' …"(Einhorn & Hogarth, 1982, p. 24).
  54. Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). p. 147.
  55. See Robinson, J.B., "Energy Backcasting: A Proposed Method of Policy Analysis", Energy Policy, Vol.10, No.4 (December 1982), pp. 337–345; Robinson, J.B., "Unlearning and Backcasting: Rethinking Some of the Questions We Ask About the Future", Technological Forecasting and Social Change, Vol.33, No.4, (July 1988), pp. 325–338; Robinson, J., "Future Subjunctive: Backcasting as Social Learning", Futures, Vol.35, No.8, (October 2003), pp. 839–856.
  56. See Yeates, Lindsay Bertram (2004). Thought Experimentation: A Cognitive Approach (Thesis). pp.  139–140, 141–142, 146147.
  57. Also, see Garbey, Joerger & Furr (2023), pp. 112, 127–128.
  58. Robinson's backcasting approach is very similar to the anticipatory scenarios of Ducot and Lubben (Ducot, C. & Lubben, G.J., "A Typology for Scenarios", Futures, Vol.11, No.1, (February 1980), pp. 51–57), and Bunn and Salo (Bunn, D.W. & Salo, A.A., "Forecasting with scenarios", European Journal of Operational Research, Vol.68, No.3, (13 August 1993), pp. 291–303).
  59. p. 814, Dreborg, K.H., "Essence of Backcasting", Futures, Vol.28, No.9, (November 1996), pp. 813–828.
  60. Jansen, L., "Towards a Sustainable Future, en route with Technology", pp. 496–525 in Dutch Committee for Long-Term Environmental Policy (ed.), The Environment: Towards a Sustainable Future (Environment & Policy, Volume 1), Kluwer Academic Publishers, (Dortrecht), 1994.
  61. Catholic Encyclopedia (1913)/Pandects "every logical rule of law is capable of illumination from the law of the Pandects."
  62. Plato. Rep. vii, I–III, 514–518B.
  63. Seyyed Hossein Nasr and Oliver Leaman (1996), History of Islamic Philosophy, p. 315, Routledge, ISBN   0-415-13159-6.
  64. Yeates, 2004, pp. 138–143.
  65. Jaynes, E.T. (1989).Clearing up the Mysteries, opening talk at the 8th International MAXENT Workshop, St John's College, Cambridge UK.
  66. French, A.P., Taylor, E.F. (1979/1989). An Introduction to Quantum Physics, Van Nostrand Reinhold (International), London, ISBN   0-442-30770-5.
  67. Wheeler, J.A, Zurek, W.H., editors (1983). Quantum Theory and Measurement, Princeton University Press, Princeton.
  68. d'Espagnat, B. (2006). On Physics and Philosophy, Princeton University Press, Princeton, ISBN   978-0-691-11964-9
  69. 1 2 3 Gualeni, Stefano (2015). Virtual Worlds as Philosophical Tools: How to Philosophize with a Digital Hammer. Basingstoke (UK): Palgrave MacMillan. ISBN   978-1-137-52178-1.
  70. 1 2 Gualeni, Stefano (2016). "Self-reflexive videogames: observations and corollaries on virtual worlds as philosophical artifacts". G a M e, the Italian Journal of Game Studies. 1, 5.
  71. While the problem presented in this short story's scenario is not unique, it is extremely unusual. Most thought experiments are intentionally (or, even, sometimes unintentionally) skewed towards the inevitable production of a particular solution to the problem posed; and this happens because of the way that the problem and the scenario are framed in the first place. In the case of The Lady, or the Tiger?, the way that the story unfolds is so "end-neutral" that, at the finish, there is no "correct" solution to the problem. Therefore, all that one can do is to offer one's own innermost thoughts on how the account of human nature that has been presented might unfold – according to one's own experience of human nature – which is, obviously, the purpose of the entire exercise. The extent to which the story can provoke such an extremely wide range of (otherwise equipollent) predictions of the participants' subsequent behaviour is one of the reasons the story has been so popular over time.

Further reading