Can we say, with respect to reality, that "I AM not just What I AM"? That, aside from things actually existing or having been in the past, the real possibilities too must be treated as part of reality for all intents and purposes -- for example, to exert free will as a conscious choice?

Does modern philosophy has the concept of "real possibility"?

Also, following up on comments, "How do we know something was, in fact, possible since it did not happen?"

There are two ways to word the answer. Using modern terms, this particular superpower -- knowing what's possible -- is something we have evolved as humans. No other species on the planet have it. It was the purpose of our genus' evolution over the course of the last 5 million years, and it makes us who we are -- for better or worse.

At the heart of our humanity lies the highly specialized computing hardware of our prefrontal cortex. The rest of the brain we have inherited from our animal ancestors as-is, and it is a good ole Neural Network supercomputer. However, the prefrontal cortex resembles traditional architecture: a rather basic arithmetic/logic unit paired with a much more capable graphics processor. It's good for imagining (or daydreaming) virtual realities -- from pure fantasies to realistic real-world simulations. The latter could mean seeing those "real possibilities", given that the person possesses the necessary skills and their knowledge of the real world is reasonably complete and accurate... None of which we are, sadly, born with (so much for intelligent design).

Instead, we are simply given extra 4-5 years of childhood to allow for the essential skills and knowledge to be shared with us by supportive adults and older children. And they have been, for most of our history, teaching that art to every child -- the art of being your rational, conscious Self. Back then, we didn't know about evolution, we didn't know how exactly it works, but we knew that every person -- their Self, their human soul -- is made in the Ultimate Reality's own image, and that's how they can know the world!

But it is no coincidence that our prefrontal cortex is hardwired for 3-dimensional space, with the rules of inference, logic, and reason that we find behind every act of creation, the rules that make the world go round. We end up this way because we have evolved being a part of this world, this reality:

"Through [the Logos] all things were made; without it, nothing was made that has been made."

In other words, as children, we should have been taught to use our rational minds properly. However, for reasons too sad to mention we weren't... so we aren't!

"... In it was life, and the life was the light of men. And the light in darkness shineth; and the darkness comprehended it not."

  • What would be the difference between a real possibility and a normal one ?
    – armand
    Commented Jan 18, 2021 at 23:05
  • Are you including foreseeable risk as a “real possibility”? Commented Jan 18, 2021 at 23:13
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    Lewis treats possible worlds as "real", but I doubt they are relevant to your ethical angle. Your "real possible" sounds more like what Aristotle called "potential", and Deleuze "virtual", see How does the concept of the 'virtual' (Deleuze) relate to 'counterfactuals' (Lewis)? Also, Peirce's "real generals" and "would bes" might be of this sort.
    – Conifold
    Commented Jan 18, 2021 at 23:20
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    @armand -- the distinction is between real possibility and fantasy. Both are products of our imagination. A real possibility is a what-if -- an outcome that would exist in reality as a result of different initial conditions (e.g. us making a different choice). Otherwise, it's just a fantasy. Commented Jan 19, 2021 at 2:37
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    @Conifold -- thanks, Deleuze concept of the virtual part of reality is what I meant by "real possibility" Commented Jan 19, 2021 at 2:45

3 Answers 3


The general area is the topic of counterfactuals.

Statistical probabilities derived from the past are inherently based on counterfactuals, which works when there are simple constituents which we can rely on to be unbiased, and equivalent: coins being flipped, fundamental particles. Bayesian probability works instead by comparing expectations which can come from reasoning alone, with outcomes.

When we consider counterfactuals about our own lives, we rely on proposing different outcomes that are similar enough, which is to say models based on valid abstractions.

We understand solid bodies, intuitively, through what will happen if they are rotated or translated, interacting with other objects, like our hands. I'd say it's reasonable to say those qualities are part of an object: it's mass, binding energy, and so on will impact these behaviours. They result from symmetries, the most fundamental idea we have in physics about what things are.

Yes choice-making is fundamentally dependent on that, tuned by evolution/biology and reasoning and experience, selecting between outcomes. Sets of possible outcomes relate in a deep way to what things are, and correctly judging them constitutes real knowledge about the world, and underpins our intentions.

General Relativity addresses 4D. The Holographic Principle deals with an additional fractional dimension. String Theory proposes 11D. Our intuitions may be tuned to 3D, but I'd say there is a fundamental flexibility to awareness, not limited to that.


The quick answer is that if a possibility is real, then an adequate description of reality includes it. But that's probably a bit too quick.

I would approach the question by way of an example. Suppose I am offered a choice between options 1 and 2. Suppose further that I can make a choice and I actually decide on option 2. If I was genuinely able to choose between options 1 and 2, so that the state of the world and the laws of nature did not foreclose either option, then an adequate description of the world, of reality, includes and must include the possibility of my choosing option 1 instead. That this possibility was unrealised, since I chose option 2, does not affect its status as a possibility - and as such it is or rather was 'a part of reality'.

A determinist for whom the future is foreclosed, so that I could not have chosen other than I did, would deny that there was any possibility of my choosing option 1. On this approach, there was no possibility to be realised and so no possibility to be 'a part of reality'.

The moral is that this is not a free-standing question. Its answer depends on a metaphysical position - in my example, that position is one's stance on determinism. (Or the version of determinism I have lightly sketched or rather assumed.)

If David Lewis's modal realist theory of possible worlds is correct and possible worlds are real, really existent, then the possibilities they contain are real - and so 'a part of reality'. You pays your money and takes your choice (but on 'choice' see above). For myself and like Kit Fine, I have never been able to accept that 'possible worlds and their inhabitants are just as real as the actual world and its inhabitants' (K. Fine, Modality and Tense, Oxford: Oxford University Press, 2005:1). Perhaps this is just a failure of imagination, or perhaps Lewis's imagination was too strong.

  • There is no concept of "possibility" or "option" or "choice" in determinism. There is no uncertainty of any kind. Determinism is not a description of reality at all. Commented Aug 11, 2021 at 6:55
  • This is consistent with my answer. A determinst still has access to the concepts of possibility, choice, and option: and denies that they have application.
    – Geoffrey Thomas
    Commented Aug 11, 2021 at 7:05
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    A determinist is an illogical creature. He entertains the possibility that there is no concept of possibility. He chooses to ignore all opportunities to choose. Commented Aug 11, 2021 at 7:41
  • @PerttiRuismäki: Pribabilities are still meaningful where data is limited. Eg, a dice roll or roulette wheel outcome are fully predictable from initial conditions (even in a quantum world), but probability theory is still useful where those, as in the usual case, are not known. Ideal gas theory & thermodynamics in general, come from large assemblies considered statistically, so the existence of true data about atoms cannot be said to make probabilities related to them lack application.
    – CriglCragl
    Commented Sep 10, 2021 at 16:17

Possibilities are taken into evidentiary account by the law.

For example, an accused's psychological state - Eg: remorseful, unstable, defiant, delusional - is considered as a means by which to evaluate the likelihood of certain future behaviours, especially reoffending.

Evidence is taken into account during this process - such as evidence of past behaviour and evidence provided by character references - and as such it could be considered that these evidences constitute evidence useful to the calculation of a likelihood of future behaviour; in other words, as evidence for certain possibilities.

Imagine a scenario in which a person stands accused of having committed a serious assault. There is a bail hearing, in which the judge is tasked with determining whether or not the accused presents an unacceptable risk to the community. The judge receives evidence which shows the accused had a spotless record prior to the assault, and that the assault was allegedly perpetrated against a specific person, for a very specific reason (ie. that the victim had been caught breaking into the accused's child's bedroom). The accused expresses seemingly sincere remorse for the injuries inflicted, has strong ties to the local community, and presents no obvious danger to anyone else. Based upon this information, the judge assesses the possibility of future violent offending as acceptably low and releases the accused on bail, back into the community to await the next court hearing.

In other words, in the absence of foreknowledge, many, many things may be deemed as real possibilities (for example, that the accused might still harbour ill-will towards the victim and seek to assault him again), but they are weighed against other possibilities in an attempt to more accurately determine what is actually possible and may be likely to occur. ​

So, insofar as 'real possibilities' are defined as 'those things which, in the absence of foreknowledge, might be able to occur', then yes, they are considered as part of a reality; a reality in which imagined events prove useful to the determination of what will actually eventuate.

Possibilities are derived from evidence and employed as a worthwhile predictive tool, but they also constitute evidence, for evidence can take the form of statements of fact about what is possible. If the victim's lawyer was able to demonstrate that the accused had the means, the motive and the opportunity to assault the victim again if released on bail, the 'real possibility' of the assault becomes evidence pertinent to the judge's final decision.

So... in this way, the accused becomes more than what he is, he becomes a potential person; and this potential person must be acknowledged by the court if it is to best address its responsibilities to the community.

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