Possibility: what is conceivable, probable, and physically admissible

Epigraph

“The contrary of every matter of fact is still possible […]”

David Hume, An Enquiry Concerning Human Understanding, E 4.2, SBN 25–26. A checked opening clause; the omission is marked. Hume next discusses contradiction and distinguishes evidence for matters of fact from relations of ideas. This historical philosophical formulation is not a complete contemporary criterion of physical admissibility. Context.

What this article is about

The word “possible” can open a discussion or conceal a missing justification. We imagine an event, find no contradiction in its description, assign it a nonzero probability, or examine its physical conditions—and use the same word for all four results. Yet these are different achievements. An imagined route may remain unavailable to a traveller; two named outcomes need not be equally probable; an intelligible picture need not describe an admissible physical process.

This article clarifies possibility through the question being asked, the conditions stated, and the kind of check available. We compare bounded passages from Hume, Descartes, and Laplace, then examine a physical boundary through Einstein’s definition of simultaneity. These authors do not provide one shared theory: their differences reveal transitions requiring additional grounds. Ordinary hypothetical examples separate thought from existence, probability from enumeration, and practical access from a general description. The final practice invites you to examine one claim about a possible event while preserving both open questions and established limits.

I. Possibility belongs to a particular question

Imagine someone suggesting that a small meeting be moved to another room. One participant says, “That is possible.” Another hears that the room is available; a third assumes that the group fits; a fourth thinks the organiser has approved the move. Yet the reply may mean only that no obvious objection has occurred to the speaker. Several questions have been compressed into one short sentence. Naming the actual result—capacity, access, consent, or merely an idea—makes the remaining conditions visible without accusing anyone of careless speech.

A claim of possibility usually needs a qualification: under what conditions, for whom, and in what respect? A room may be large enough but locked at the required hour. The move may be technically feasible without having been agreed. Someone can describe a sequence of actions while lacking the time to carry it out. There is no need to select one correct meaning for every situation. We need to retain the meaning relevant to this question; otherwise, people dispute different things while believing that they are considering the same fact.

We will use several working distinctions. Conceivability means that an option has been imagined or described. The absence of an established contradiction concerns the consistency of that description. Physical admissibility requires specified laws, quantities, and conditions. Probability belongs to a model and the information used with it. Practical availability adds the resources and constraints of a particular action. This arrangement is our way of reading the examples, not a quotation from a common doctrine of the four authors. It does not exhaust every philosophical use of “possible,” but helps us examine transitions between them.

A small replacement can begin the process: instead of “the move is possible,” say, “this room has enough seats, but access has not been confirmed.” The claim becomes more modest and more useful at once. We preserve an established fact without presenting it as a solution to the whole problem. The next step is also clear: establish access rather than prove capacity again. This way of speaking does not require complete certainty in advance. It permits action with partial knowledge while retaining its boundaries and without making uncertainty a prohibition on every initiative.

II. A consistent description does not establish a fact

At the beginning of the fourth section of the Enquiry, Hume distinguishes relations of ideas from matters of fact, E 4.1–4.2. His arithmetic example concerns a relationship between numbers; denying that relationship differs from making the contrary claim about an event. The familiar example of tomorrow’s sunrise illustrates different grounds of judgment: an intelligible contrary description is not proof that the contrary event actually occurs. We do not treat his historical formulation as a complete classification of physical possibilities. Our question concerns the transition from a coherent thought to knowledge of what happens.

Consider a closer hypothetical case. “The parcel arrived yesterday” contains no obvious contradiction. “The parcel has not arrived” is equally intelligible. Their intelligibility does not establish that both describe the same fact at the same time and in the same sense. We need delivery evidence, a clarified address, or an inspected record. Imagination helps us formulate alternatives; information helps us discriminate between them. These activities can support one another, but neither automatically replaces the other. Understanding a sentence and establishing its truth remain separate tasks even when the sentence feels entirely ordinary.

We can also miss a contradiction because a description is incomplete. An “always open closed room” sounds inconsistent until we learn that it is open during the day and closed at night. The clarification removes that apparent conflict. If both words concern the same entrance at the same moment, the description needs further revision. It is therefore useful to distinguish a failure to notice an error from an actual consistency check. The former often records only an initial result of attention. It does not permit us to treat an intelligible account as a rigorous proof that any event is admissible.

Everyday conversation need not become an exercise in formal logic. Retaining the object and time of a claim can suffice. “We may still be able to collect this parcel today” is a reasonable hypothesis if opening hours are unknown. Confirmation that the office has closed changes the plan’s status. We need not call the original thought meaningless: it helped formulate a question that could be checked. But we cannot set the new information aside merely because the option remains easy to imagine. An intelligible picture does not release a factual claim from attention to actual conditions.

III. Imagining existence does not confirm it

In Part IV of the Discourse on Method, Descartes considers a geometrical triangle. He separates conclusions about the properties of the conceived figure from assurance that such a figure exists in the world. The passage belongs to his argument about God and certainty; we do not transfer that entire argument into contemporary fact-checking. Its local distinction nevertheless helps us ask what our description provides: a relationship between properties or evidence that an object exists. These results may require different grounds even when their descriptions closely resemble one another.

Suppose we design a cabinet with specified compartments. Its drawing has consistent dimensions, its modelled doors open, and other people understand the design. All this may represent good work on a project. It does not establish that the cabinet has been manufactured, that the required material is available, or that it fits a particular home. Some information concerns the proposed construction; other information concerns an existing object and its intended location. Confusing them turns a useful achievement into a broader promise that has not yet been checked by anyone involved in the project.

Conversely, an object’s presence does not confirm every property attributed to it. We can see a cabinet while knowing neither its exact dimensions nor the load a particular shelf can support. The distinction operates in both directions: an intelligible description does not prove existence, and encountering something does not complete the investigation of its characteristics. In our hypothetical example, dimensions can be measured and checked manufacturer information consulted. Those checks concern particular claims. They do not require us first to settle the general philosophical question of whether an external world exists at all.

The distinction is particularly useful when discussing future projects. “We can describe it,” “we have a consistent model,” and “the conditions for manufacture have been confirmed” are separate results. Acknowledging the first does not devalue it: many tasks become discussable only through a description. Yet a model need not be defended by inventing an existing fact. Naming the stage honestly allows the work to continue—establish the material, check dimensions, identify the unknown. Possibility becomes a question about which transitions have grounds and which remain open, rather than a reward for speaking with confidence.

IV. A physical claim needs physical conditions

In the first section of his 1905 paper, Einstein examines time and simultaneity. Clocks at different locations require a stated procedure of synchronisation using light signals. Saying “at the same time” is insufficient without explaining how the comparison is made. We use Perrett and Jeffery’s English translation with Walker’s editorial corrections; the definition is considered here without independently reproducing every conclusion in the paper. This is an example of an understandable everyday expression acquiring conditions that make a physical claim workable and its grounds available for discussion.

It is easy to imagine two lamps flashing simultaneously. A check nevertheless needs clock locations, the method used to compare their readings, and a definition of the events’ times. The imagined picture does not already contain all that information. The example establishes neither that time is an arbitrary personal fantasy nor that every inconsistent description is equally admissible. Rather, a procedure makes some assumptions explicit. We can discuss how a conclusion was reached instead of treating the strength of an inward impression as if it were a physical measurement.

The physical side of our hypothetical cabinet project also appears through parameters. We need the passage dimensions, a component’s mass, material properties, and a construction method. “I can picture the cabinet going through the doorway” does not replace measurement. Yet measuring one doorway does not finish the task: the route may include a turn omitted from the check. We are not deriving construction standards from relativity. The comparison concerns the organisation of a question: physical claims need specified objects, quantities, and conditions, rather than an imagined picture that happens to feel convincing.

Not knowing the conditions is also different from establishing impossibility. If the turn has not been measured, the appropriate status is an open question. Measurements showing incompatible dimensions change that status: this option fails under these conditions. The construction or route might be revised, but that would be a new option with new assumptions. This precision preserves room for exploration while respecting an established constraint. We can revise a plan without declaring every inconvenient result a mere convention, and without treating each unfinished check as a final prohibition on proceeding.

V. Probability does not arise from a single word

In Chapter II of the Philosophical Essay on Probabilities, Laplace connects probability with knowledge and ignorance. His urn examples specify the composition of cases and the available information. The opening of Chapter III separately introduces a condition of equal possibility. We use Truscott and Emory’s 1902 translation, not the French original. These passages help distinguish listing alternatives from constructing a probability model. Laplace’s ideal of an all-knowing intelligence does not imply that a person already possesses every item of information required for a numerical forecast.

Imagine an opaque box containing four identically shaped cards: three marked with a circle, one with a square. Our hypothetical rule explicitly gives every card an equal chance of being drawn. The two named shapes then have unequal probabilities: the circle corresponds to three of four cases and the square to one. That result follows from the specified contents and rule, not from the number of words in the question. If the drawing method differs or the contents are unknown, we cannot transfer the calculation without checking. It describes this model rather than every possible box.

“This can happen” tells us much less. It may mean only that an option has entered the discussion. Calling it probable requires an additional meaning of that word and appropriate information. In conversation, “probably” sometimes expresses an expectation without assigning a number; stating its grounds can be useful. In a formal model, a number acquires meaning through the trial’s construction. We cannot take a nonzero probability from an unspecified model and present it as a guarantee of an event’s real-world existence. The relationship between model and subject also needs justification beyond the model’s internal calculations.

A number does not become reliable through precise typography. Assigning many decimal places without data or a calculation rule merely conceals the difficulty. “Not yet estimated,” by contrast, can accurately describe the work’s status. In our meeting example, the probability of agreement does not follow from the presence of two answers, “yes” and “no.” Discussing an expectation might involve asking participants about their views and the conditions of a decision. One participant’s opinion is not a random card draw; consent cannot be calculated from a symmetry between two words used to describe it.

VI. Missing information does not establish equal alternatives

It can seem fair to give equal weight to everything about which little is known. Yet missing information about a difference does not establish equality. If we do not know the box’s contents, saying “half the cards have circles” adds information we do not possess. We can temporarily adopt such a model to explore its consequences. If we do, the assumption must remain visible rather than being presented as a discovered composition. Conditional calculation and checked observation remain distinct even when an assumption looks simple, familiar, and convenient for the conversation taking place.

Return to the meeting. We may not know whether the room is available and consider two states: free or occupied. That ignorance does not show that the schedule divides equally between them. Other relevant states might include free but locked, accessible only with a supervisor, or not yet designated for events. Our first division may have omitted distinctions relevant to the decision. Before evaluating alternatives, we should examine which differences matter. In some tasks, asking one clarifying question provides more useful information than completing a calculation based on two arbitrarily selected outcomes that do not cover the actual situation.

An established constraint should also remain within its scope. A room occupied in the morning does not establish that the meeting cannot happen in the evening. If it is locked throughout the day, this option fails for that day, but not every version of the meeting is excluded. We clarify time, access, and the subject of the claim. This is not wordplay that dismisses an inconvenient fact. The fact is retained within its domain; a different time starts a separate question. A reliable constraint does not become universal simply because a failed plan feels upsetting to someone involved.

We can record three statuses: established, provisionally assumed, and unknown. A checked schedule belongs to the first; an assumed duration to the second; agreement not yet obtained to the third. The next step then becomes easier to identify. A changed assumption calls for a revised conditional conclusion; new information removes some uncertainty. The record neither makes anyone infallible nor turns the task into a numerical model. It helps us avoid replacing missing information with invented symmetry, and prevents an appropriate expression of caution from being mistaken for knowledge already acquired through a check.

VII. An admissible option may be unavailable here

Physical admissibility and practical availability differ even in ordinary tasks. A meeting can fit a room of a certain size while this group cannot obtain that room on the required day. We can describe an object without finding a contradiction, while its manufacture still requires material, time, and skill. These additional conditions do not turn the general idea into a mistake. They show that possibility for a particular person involves more than a proposed construction’s admissibility. Identifying the missing condition helps before issuing a final judgment about the whole task and all its potential forms.

Practical availability also involves other people. An organiser cannot treat their consent as a resource already possessed merely because a request has been phrased reasonably. We can propose an option, explain its conditions, hear a refusal, or consider a counterproposal. An opportunity to ask is not a right to determine another person’s decision. Our working arrangement preserves the difference between one’s own action and an anticipated response. This is the article’s ethical judgment about a hypothetical meeting, not an instruction on relationships attributed to Hume, Descartes, or Einstein from the passages used here.

Some constraints can be changed: choose another time, simplify a construction, or find an accessible location. Each revision nevertheless has a cost and further conditions. An imaginable workaround does not by itself make an option available. We must establish whether it suits the participants, how much time it requires, and what constraints it introduces. Nor must every conceivable workaround be investigated. Someone can conclude that this project does not fit the present situation and stop searching. The possibility of continuing a discussion does not become an obligation to prove one’s determination indefinitely through further attempts.

Clarification is not intended to reduce the scale of someone’s wishes in advance. It connects a proposal to conditions relevant to action. “I want to try” and “I confirm the result” can honestly belong to different stages. The former leaves room for experience and agreement; the latter requires evidence. Preserving that boundary allows a small check without a promise of complete success. Acknowledging constraints need not cancel initiative. It can help someone choose a concrete form for it: propose, measure, ask, compare, or postpone for a reason that is both understandable and specific.

VIII. Moving between meanings requires further grounds

A quiet chain can form in conversation: an option is imaginable, therefore admissible; admissible, therefore probable; probable, therefore about to happen. Each transition needs its own grounds. A coherent description does not automatically provide a physical check. Physical admissibility does not establish high probability in this particular situation. High probability in a justified model does not guarantee an individual outcome. Where grounds are absent, the chain can stop at the result actually obtained. This does not prohibit the next question; it identifies what work would be needed to investigate it with more than a confident assertion.

The historical authors help reveal different transitions, but combining them into one answer would lose their differences. Hume’s selected passage concerns evidence for facts; Descartes considers a conceived figure within another philosophical argument. Laplace discusses probability and completeness of knowledge; Einstein defines a comparison of times. The connection belongs to our question about a conclusion’s assumptions. It does not establish that the authors understood knowledge, existence, physical law, or human reason in the same way. Their usefulness for this comparison cannot be turned into proof of agreement across their entire subjects or philosophical projects.

Suppose our cabinet drawing has passed a dimensional check. Material is the next question. Without information about it, “the construction has been fully confirmed” exceeds the check’s scope. If material is selected but availability is unknown, one particular question remains open. We can organise these questions without creating an endless demand for an absolute guarantee. A small reversible trial may require one level of information, a substantial commitment another. This proportionate judgment concerns the consequences of an error and the actual task. It does not follow merely from how strongly someone believes in the proposed option’s possibility.

Distinguishing a model’s limitations from the world’s properties is especially helpful. A model may omit a factor without showing that the factor is absent in reality. It may permit several options without establishing which one occurred. Finally, a model may contain an assumption that does not fit the task. Increasing confidence cannot solve that problem. We need to revise the description, check its relationship to the subject, or acknowledge that the available information does not support this conclusion. Clarifying the grounds can reveal a boundary and a next step together, rather than forcing a choice between them.

IX. An open possibility need not become a promise

Possibility often enters a conversation through hope. Someone wants to preserve an option that information has not yet confirmed. That relationship to the option can be respected without being presented as proof. “I want this meeting to happen” describes a wish; “the room and time have been confirmed” describes checked conditions. Neither sentence must replace the other. We can support an idea while clarifying its open questions. This allows discussion of a next step without requiring anyone to accept another person’s confidence as an obligatory description of the facts or of their own position.

Missing a guarantee does not make an attempt meaningless. In our hypothetical example, sending a request, checking a schedule, and establishing access can produce information even if the original option fails. A new decision then has grounds: change the time, select another format, or stop. A check’s value does not depend on always confirming the desired outcome. A failure concerning one condition may improve the task’s description. It does not establish a general deficiency in a person, an inability to act, or the uselessness of every future proposal that has not yet been considered in its own circumstances.

The reverse boundary also matters: one successful check does not guarantee the whole project. An available room leaves the question of group agreement; agreement may leave organisational details. We need not worry in advance about every imaginable obstacle. Identifying the substantial conditions of the present decision and a way to investigate the unknown can suffice. The appropriate attention depends on the task and the consequences of error. The record suggested here supports a discussion of conditions, but its psychological or educational efficacy has not been studied. It is not an obligatory thinking method for every reader encountering an uncertain choice.

Possibility becomes clearer when a proposal ends with a precise verb: imagine, check, calculate, propose, or carry out. These activities can support one another while retaining different results. Imagination supplies an option for discussion; a check establishes something about a condition; calculation operates within a stated model; a proposal leaves room for another person’s response; execution requires available conditions for action. Such a conversation accommodates imagination, knowledge, and choice. We need not declare every dream already feasible, or every unknown already impossible, to begin an honest and appropriately small next step in the task before us.

What this means in practice

Select one ordinary statement containing “possible,” such as a proposal about the location or time of a small meeting. Write down what should happen and when. Then clarify what the word means here. Have you merely imagined an option, checked a particular inconsistency, established physical conditions, constructed a probability model, or confirmed access to an action? Several results can be recorded while remaining separate. The example need not concern health, safety, or another person’s private circumstances to make this practice meaningful and sufficiently concrete for examination.
Name one established condition and one unknown. If information came from a schedule, retain the relevant day and entry; if it came from a person, retain the actual meaning of the reply. Do not turn “perhaps” into consent or add an unstated promise. Record your own assumption separately. This does not prove that the entire task will succeed, but reveals where a conclusion rests on information and where it depends on a provisional description. If a substantial constraint is already known, preserve it without inventing a reassuring exception that has not been checked.
Examine one transition. Have you inferred existence from an intelligible description, complete success from one available condition, or equal probability from two named answers? State the additional grounds that would be needed. Then choose a proportionate step: consult an applicable record, measure a relevant quantity, ask an ordinary question, or revise the option. You need not perform every imaginable check. Select the next one relevant to a substantial condition of this decision and acceptable to the participants without putting pressure on the answer they should give you.
Finish with two sentences: “What is established now is…” and “The next question is…” If the question has been settled negatively, you can add, “This option does not fit these conditions.” If it remains unsettled, retain that status instead of inventing a number. You may revisit the record when information arrives and change only the relevant conclusion. The practice offers a way to clarify a discussion, rather than promising a particular psychological result. It can be shortened, adapted, or left without further steps once the task is sufficiently clear for your next action.

Key quotation

“Probability is relative […]”

Pierre-Simon Laplace, A Philosophical Essay on Probabilities, II, F. W. Truscott and F. L. Emory’s 1902 translation. The checked opening clause is excerpted with a marked omission; the continuation relates probability to ignorance and knowledge. This permits neither arbitrary numbers nor the claim that every opinion has equal grounds. The French original was not checked. Context.

Connections between traditions

Comparison	Working connection	Boundary
Hume, E 4.1–4.2 / Descartes, IV, the geometrical triangle	Distinguish a conceived relationship of properties from evidence of fact or existence.	Hume’s account of evidence and Descartes’s argument about certainty differ; no shared metaphysics is established.
Descartes, IV, conception and existence / Laplace, II, ideal intelligence	Describing a thought construction does not make its knowledge available to a person.	A geometrical figure and an ideal of complete knowledge serve different purposes; the comparison belongs to this article.
Hume, E 4.3–4.6 / Laplace, II, urn information	An inference about a case needs stated evidence, or a model and information.	A philosophical account of expectation is not a numerical probability calculation.
Hume, E 4.2, contrary description / Einstein, §1, clock synchronisation	An intelligible event description does not already contain its physical checking procedure.	Hume supplies no criterion of modern relativity; defining physical time does not settle every question about facts.
Laplace, III, second principle / Einstein, §1, clocks A and B	Equal possibility of cases and a comparison of times require stated conditions rather than two words.	A probability assumption and a physical synchronisation procedure are different mechanisms.
Descartes, IV, a figure’s properties / Einstein, §1, defining time	Clarify which relationships have been specified for the kind of claim being made.	A geometrical example in philosophical argument is not a clock experiment; no common doctrine is asserted.

Six original comparisons of specified passages, without a claim of a shared project or historical borrowing.

Primary sources

David Hume, An Enquiry Concerning Human Understanding, E 4.1–4.6, original English in Hume Texts Online, E/SBN locators. These paragraphs were read completely; E 4.7 only in its opening. This page’s print edition was not established here.
René Descartes, Discourse on Method, IV, John Veitch’s translation, Project Gutenberg 59. Complete IV and the specified opening of I read during this task; the triangle passage is used. The French original was not checked.
Pierre-Simon Laplace, A Philosophical Essay on Probabilities, Truscott/Emory, 1902, from the sixth French edition. Complete I–II and the first three principles of III read. The remainder and French text were not checked.
Albert Einstein, On the Electrodynamics of Moving Bodies, 1905, Perrett/Jeffery, 1923, Walker’s 1999 edition. Introduction and §1 read completely; §2 only in its opening. German original and subsequent proofs were not independently checked.

About the authors

Andrey Zarinsh is the author and founder of United Wisdom. He explores inner transformation, the unity of traditions, intercultural dialogue, and contemporary spiritual discipline. Instagram: @andrey.zarinsh.

Maria Evilkut is a co-author of United Wisdom. Alongside her research, she seeks to test these ideas in practice and observe how principles of unity and mutual understanding work in real life between people and cultures. Instagram: @ilkutki.