Read This First
If this page feels abrupt, start here
These links provide the wider frame, earlier distinction, or branch map that makes the current page easier to enter.
-
Metaphysics Branch Guide
If this page feels abrupt, start with the Metaphysics branch guide so the wider map is visible before the close reading begins.
Read This Next
If the page clicked, continue here
These are not just nearby pages. They are the strongest next moves if you want the pressure of this page to keep unfolding.
-
Metaphysics – Core Concepts
Metaphysics – Core Concepts keeps the same branch pressure in view but turns it from a different angle.
-
What is Metaphysics?
What is Metaphysics? keeps the same branch pressure in view but turns it from a different angle.
-
Ontological Domains
Ontological Domains keeps the same branch pressure in view but turns it from a different angle.
Prompt 1: Consider the following types of impossibility. Do they fall into a nested order? Are there other significant types of impossibility that should be considered in metaphysics?
Are there other significant types of impossibility that should be considered in metaphysics?
Keep Types of Impossibility, Logical Impossibility, and Metaphysical Impossibility in the same frame. Each piece is doing a different job, and the page gets muddy if the reader cannot say what is being identified, what is being tested, and what would change if one piece disappeared.
In plain terms: In metaphysics, the following types of impossibility are often discussed.
Keep Types of Impossibility distinct from Logical Impossibility. They are not interchangeable bits of vocabulary; they point the reader toward different judgments, objections, or next steps.
A quick way to test the page is to imagine an ordinary disagreement in which A Taxonomy of Impossibilities matters. What would a careful reader now say, test, or withhold because Types of Impossibility and Logical Impossibility has been made clearer? If the page cannot answer that, it still needs more contact with life.
The first move should give the reader something firm to hold. Then the later prompts can deepen the issue instead of circling it.
A fair pushback is that the familiar way of speaking about the familiar reading already seems good enough. The page should answer that in plain language: what mistake does the familiar wording invite, and what becomes clearer if we tighten the distinction?
Treat Types of Impossibility, Nested Order, and Other Significant Types of Impossibility as handles, not slogans. The question should remain open enough for revision but structured enough that disagreement is not mere drift. The metaphysical pressure is to distinguish what must be true, what may be true, and what language merely makes easy to imagine.
This sits at the foundation. It refers to things that violate the basic laws of logic. Statements like “A square circle exists” or “It’s raining and not raining at the same time” are logically impossible because they contradict themselves.
Building on logic, this deals with things that are impossible based on the fundamental nature of reality. If, for example, our reality is based on the laws of physics as we understand them, then things like perpetual motion machines or traveling faster than light might be considered metaphysically impossible.
This is the most specific category. It refers to things that are impossible given the current state of the physical world and our understanding of its laws. Cloning humans might be physically impossible today, but not necessarily metaphysically impossible. With advancements in science, it could become physically possible in the future.
This refers to things that we cannot know for certain, even if they might be logically or metaphysically possible. For instance, the existence of life on other planets might be epistemically impossible with our current technology.
This deals with actions that are considered fundamentally wrong, even if physically possible. Torture or genocide might be considered morally impossible.
This refers to statements or propositions that are self-contradictory or violate the fundamental laws of logic. For example, the statement “A is both B and not B at the same time and in the same respect” is logically impossible, as it violates the law of non-contradiction. Logical impossibilities are considered the most fundamental and encompassing form of impossibility, as they contradict the very foundations of rational thought and discourse.
This category includes statements or propositions that are not self-contradictory in a purely logical sense but are still considered impossible based on our understanding of the fundamental nature of reality or existence. For example, the claim “A thing can exist and not exist at the same time and in the same respect” might be considered metaphysically impossible, even though it is not strictly logically impossible. Metaphysical impossibilities are typically seen as a subset of logical impossibilities, as they still violate certain metaphysical principles or laws that are considered necessary truths about reality.
This refers to events, processes, or states of affairs that are impossible according to the known laws of physics or the observable regularities of the natural world. For example, the claim “An object can travel faster than the speed of light” is considered physically impossible based on our current understanding of physics. Physical impossibilities are generally considered a subset of metaphysical impossibilities, as they are ruled out by the broader metaphysical framework within which the laws of physics operate.
This refers to propositions or ideas that are impossible because they involve incoherent or contradictory concepts, even if they are not strictly logically impossible. For example, the idea of a “married bachelor” might be considered conceptually impossible, as it involves a contradiction in the definitions of the concepts involved.
This category refers to events or states of affairs that are impossible given the actual laws of nature that govern our universe, even if they are not logically or metaphysically impossible in an absolute sense. This category is sometimes distinguished from physical impossibility, which is based on our current understanding of physics, while nomological impossibility is based on the actual (and potentially unknown) laws of nature.
This category encompasses propositions or statements that are impossible to know or verify given our cognitive limitations or the available evidence, even if they are not necessarily impossible in an absolute sense.
- Types of Impossibility: In metaphysics, the following types of impossibility are often discussed.
- Logical Impossibility: Logical Impossibility refers to something that is contradictory or violates the laws of logic, such as the law of non-contradiction.
- Metaphysical Impossibility: Metaphysical Impossibility encompasses scenarios that are logically consistent but cannot exist in any possible world due to the nature of reality itself.
- Physical Impossibility: Physical Impossibility pertains to phenomena that violate the laws of physics in the actual world.
- Nested Order: Logical Impossibility is the broadest category because anything logically impossible is also metaphysically and physically impossible.
- Other Significant Types of Impossibility: There are other types of impossibility considered in metaphysics and related fields.
Prompt 2: Create a table that coherently organizes these types of impossibility and specifies their relationship to the other types.
The real issue is what Relationships of Impossibility Types changes once it becomes precise.
Keep Relationships of Impossibility Types and Types of Impossibility in the same frame. Each piece is doing a different job, and the page gets muddy if the reader cannot say what is being identified, what is being tested, and what would change if one piece disappeared.
In plain terms: This table highlights the nested nature of logical, metaphysical, and physical impossibility while acknowledging the contextual nuances of epistemic, nomological, and practical impossibility.
Keep Relationships of Impossibility Types distinct from Types of Impossibility. They are not interchangeable bits of vocabulary; they point the reader toward different judgments, objections, or next steps.
A quick way to test the page is to imagine an ordinary disagreement in which A Taxonomy of Impossibilities matters. What would a careful reader now say, test, or withhold because Relationships of Impossibility Types and Types of Impossibility has been made clearer? If the page cannot answer that, it still needs more contact with life.
This middle step keeps the thread moving. It carries the pressure already on the table toward the next distinction instead of letting the page break into separate mini-essays.
A fair pushback is that the familiar way of speaking about the familiar reading already seems good enough. The page should answer that in plain language: what mistake does the familiar wording invite, and what becomes clearer if we tighten the distinction?
A Taxonomy of Impossibilities should remain tied to a live intellectual practice. The response earns its keep when the central distinction changes how the reader would question, compare, or revise a neighboring claim.
| Type of Impossibility | Description | Relationship to Other Types |
|---|---|---|
| Logical Impossibility | Violates the laws of logic, such as contradictions. | Broadest category. Anything logically impossible is also metaphysically and physically impossible. |
| Metaphysical Impossibility | Consistent with logic but cannot exist in any possible world. | Nested within logical impossibility. Anything metaphysically impossible is also physically impossible. |
| Physical Impossibility | Violates the laws of physics in the actual world. | Nested within metaphysical impossibility. It does not include phenomena that are logically and metaphysically possible but are prohibited by actual physics. |
| Epistemic Impossibility | Cannot be known given the current state of knowledge. | Independent of logical, metaphysical, and physical impossibility but can overlap. |
| Nomological Impossibility | Impossible according to the laws of nature as understood. | Related to physical impossibility, focusing on natural laws rather than specific physical scenarios. |
| Practical Impossibility | Infeasible given current technology, resources, or capabilities. | Context-dependent and can overlap with physical and nomological impossibility. |
| Type of Impossibility | Description | Relationship |
|---|---|---|
| Logical Impossibility | Violates the basic laws of logic (e.g., “A square circle exists”). | Foundation for all other impossibilities. Cannot exist in any reality. |
| Metaphysical Impossibility | Impossible based on the fundamental nature of reality (e.g., perpetual motion machines, given our understanding of physics). | Depends on logical laws. Informs physical and potentially epistemic impossibility. |
| Physical Impossibility | Impossible given current knowledge and physical laws (e.g., cloning humans today). | Most constrained by current knowledge within the metaphysical framework. May become possible with advancements. |
| Epistemic Impossibility | We cannot know for certain, even if logically or metaphysically possible (e.g., the existence of life on other planets with our current technology). | Limited by our current knowledge and capabilities. May become knowable with advancements. |
| Moral Impossibility | Actions considered fundamentally wrong, even if physically possible (e.g., torture, genocide). | Not directly related to logic or metaphysics, but may be influenced by them. |
| Type of Impossibility | Description | Relationship to Other Types |
|---|---|---|
| Logical Impossibility | Statements or propositions that are self-contradictory or violate the fundamental laws of logic. | Encompasses all other types of impossibility. |
| Metaphysical Impossibility | Statements or propositions that violate the fundamental nature or necessary truths about reality or existence, even if not strictly self-contradictory. | A subset of logical impossibility, but broader than physical impossibility. |
| Nomological Impossibility | Events or states of affairs that are impossible given the actual laws of nature that govern our universe. | A subset of metaphysical impossibility, but potentially broader than physical impossibility based on our current scientific understanding. |
| Physical Impossibility | Events, processes, or states of affairs that are impossible according to the known laws of physics or observable regularities of the natural world. | A subset of both metaphysical impossibility and nomological impossibility. |
| Conceptual Impossibility | Propositions or ideas that involve incoherent or contradictory concepts, even if not strictly logically impossible. | Potentially overlaps with logical impossibility, but may be considered a distinct category. |
| Epistemic Impossibility | Propositions or statements that are impossible to know or verify given our cognitive limitations or available evidence. | Not necessarily related to other types of impossibility, as it concerns epistemic limitations rather than impossibility in an absolute sense. |
- Relationships of Impossibility Types: This table highlights the nested nature of logical, metaphysical, and physical impossibility while acknowledging the contextual nuances of epistemic, nomological, and practical impossibility.
- Types of Impossibility: A table that organizes the different types of impossibility and specifies their relationships.
- Central distinction: A Taxonomy of Impossibilities helps separate what otherwise becomes compressed inside A Taxonomy of Impossibilities.
- Best charitable version: The idea has to be made strong enough that criticism reaches the real view rather than a caricature.
- Pressure point: The vulnerability lies where the idea becomes ambiguous, overextended, or dependent on background assumptions.
Prompt 3: Create a list of non-trivial facts about these types of impossibility.
The map of Trivial facts about these types of impossibility becomes useful once the parts stop doing different work.
Keep Practical Impossibility and Non-Trivial Facts about Types of Impossibility in the same frame. Each piece is doing a different job, and the page gets muddy if the reader cannot say what is being identified, what is being tested, and what would change if one piece disappeared.
In plain terms: These facts illustrate the nuanced and context-dependent nature of different types of impossibility, emphasizing their relevance in various philosophical and scientific discussions.
Keep Practical Impossibility distinct from Non-Trivial Facts about Types of Impossibility. They are not interchangeable bits of vocabulary; they point the reader toward different judgments, objections, or next steps.
Take one concrete case and run it through Practical Impossibility and Non-Trivial Facts about Types of Impossibility. Ask what depends on it, what it rules out, and what else has to move if you revise it. That is usually where the map stops looking decorative and starts earning its keep.
This middle step keeps the thread moving. It carries the pressure already on the table toward the next distinction instead of letting the page break into separate mini-essays.
A fair question is why this map is needed at all. Why not just keep trivial facts about these types of impossibility in one loose pile and move on? The section has to answer by showing what confusion appears when the parts are not separated.
A map is an argument about importance. What it puts at the center, what it treats as derivative, and what it leaves unstable all shape how A Taxonomy of Impossibilities will be understood.
For a companion resource on calibration, credence, and structured rational judgment, see Credencing.com.
In some non-classical logical systems, such as paraconsistent logics, contradictions can be true without leading to a collapse of the entire logical system.
Logical impossibility is crucial in modal logic, which studies necessity and possibility. A proposition that is logically impossible is necessarily false in all possible worlds.
Metaphysical impossibility often relates to the essential properties of objects. For example, it is metaphysically impossible for a triangle to have four sides because having three sides is an essential property of triangles.
In the framework of possible worlds, something metaphysically impossible does not exist in any possible world. This contrasts with physical impossibility, which is restricted to the actual world.
Physical impossibility is contingent upon the current understanding of the laws of physics, which can evolve over time. For instance, what was once thought physically impossible, such as heavier-than-air flight, became possible with advancements in technology.
Some scenarios deemed physically impossible in our universe could be physically possible in a hypothetical universe with different physical laws, highlighting the context-dependent nature of physical impossibility.
Gödel’s incompleteness theorems show that in any sufficiently powerful logical system, there are true statements that cannot be proven within the system, illustrating a form of epistemic impossibility.
The Heisenberg Uncertainty Principle in quantum mechanics implies that certain pairs of physical properties, like position and momentum, cannot be simultaneously known to arbitrary precision, presenting a fundamental epistemic limit.
Nomological statements often include “ceteris paribus” (all else being equal) clauses. Something nomologically impossible under such conditions might become possible if other factors change.
What is considered nomologically impossible can shift with changes in scientific paradigms. For instance, Newtonian physics considered certain phenomena impossible that quantum mechanics or relativity theory do not.
Practical impossibility is often tied to technological limits. What is practically impossible today, such as human colonization of distant planets, may become feasible with future technological advancements.
Practical impossibility can result from resource constraints, such as the economic or material resources required for a large-scale project, regardless of its physical or logical possibility.
These theorems prove that any sufficiently powerful formal system will always have true statements that cannot be proven within that system. This highlights that even within logic, limitations might exist on what we can definitively prove or disprove.
If the multiverse theory holds true, what’s metaphysically impossible in our universe might be possible in another. This challenges the idea of a single, absolute definition of metaphysical impossibility.
The second law of thermodynamics suggests perpetual motion machines (violating the law) might be physically impossible. Yet, on a quantum level, time reversibility is observed. This raises questions about the limits of our understanding of physical impossibility.
Epistemic impossibility can become epistemic possibility with advancements. For example, the existence of bacteria was once epistemically impossible due to a lack of microscopes.
What’s considered morally impossible can evolve over time. Human slavery was once widely accepted, but now it’s seen as morally impossible. This reflects the interplay between morals and changing social norms.
Sometimes, different types of impossibility can interact. For example, something might be physically impossible today (cloning humans) but not logically or metaphysically impossible. Advancements in science could turn the physical impossibility into a possibility.
- Practical Impossibility: These facts illustrate the nuanced and context-dependent nature of different types of impossibility, emphasizing their relevance in various philosophical and scientific discussions.
- Non-Trivial Facts about Types of Impossibility: Logical impossibilities are considered the most fundamental and encompassing form of impossibility, as they violate the foundational principles of rational thought and discourse.
- Central distinction: Trivial facts about these types of impossibility helps separate what otherwise becomes compressed inside A Taxonomy of Impossibilities.
- Best charitable version: The idea has to be made strong enough that criticism reaches the real view rather than a caricature.
- Pressure point: The vulnerability lies where the idea becomes ambiguous, overextended, or dependent on background assumptions.
Prompt 4: Comment on and give examples of the confusion that an entanglement of different notions of impossibility can create.
A concrete case shows what Confusion from Entanglement of Different Notions of Impossibility explains and where it strains.
Keep Confusion from Entanglement of Different Notions of Impossibility and Logical vs. Practical Impossibility in the same frame. Each piece is doing a different job, and the page gets muddy if the reader cannot say what is being identified, what is being tested, and what would change if one piece disappeared.
In plain terms: The entanglement of different notions of impossibility can lead to significant confusion in philosophical, scientific, and everyday discussions.
Keep Confusion from Entanglement of Different Notions of Impossibility distinct from Logical vs. Practical Impossibility. They are not interchangeable bits of vocabulary; they point the reader toward different judgments, objections, or next steps.
Do not let the example sit there like a decorative vase. Ask what Confusion from Entanglement of Different Notions of Impossibility and Logical vs. Practical Impossibility makes easier to see in the concrete case that was easy to miss in abstraction. If nothing new becomes visible, the example has not yet done its job.
The earlier sections should already have put trivial facts about these types of impossibility in motion. The last prompt should gather that pressure into a closing judgment rather than tagging on an answer that never quite joins the rest.
A fair pushback is that the familiar way of speaking about the familiar reading already seems good enough. The page should answer that in plain language: what mistake does the familiar wording invite, and what becomes clearer if we tighten the distinction?
A Taxonomy of Impossibilities should remain tied to a live intellectual practice. The response earns its keep when the central distinction changes how the reader would question, compare, or revise a neighboring claim.
A debate about the nature of God often involves confusing logical and metaphysical impossibility. Some argue that a being omnipotent, omniscient, and benevolent cannot exist due to the problem of evil. This can lead to conflated arguments:
Arguing that the existence of such a being is logically contradictory.
Arguing that, while not logically contradictory, such a being is metaphysically impossible due to the nature of the world and the existence of evil.
Clarifying whether the impossibility is due to logical contradictions or metaphysical constraints can lead to more precise and fruitful discussions.
Discussions about faster-than-light travel can entangle metaphysical and physical impossibility. Some might argue it’s absolutely impossible, confusing:
Faster-than-light travel is impossible in any possible world.
Faster-than-light travel is impossible according to the current laws of physics in our universe.
Recognizing that faster-than-light travel is physically impossible in our universe but not necessarily metaphysically impossible helps delineate scientific constraints from broader metaphysical considerations.
Consider discussions about predicting future events, such as the exact state of the weather in a month. This can mix up:
Predicting future weather with absolute certainty is epistemically impossible due to the complexity and chaotic nature of weather systems.
Some might mistakenly argue that it is physically impossible to predict weather, whereas it’s more accurately epistemically limited by current knowledge and computational power.
Distinguishing between what we cannot know (epistemic limits) and what cannot happen (physical limits) provides clarity in scientific discussions and expectations about predictability.
The feasibility of space colonization often conflates nomological and practical impossibility:
Space colonization is impossible due to fundamental laws of nature.
Space colonization is infeasible given current technology, resources, and logistics.
Understanding that space colonization is practically impossible with today’s technology but not necessarily nomologically impossible opens up avenues for future exploration and innovation without dismissing the concept outright.
Discussing the implementation of a perfect justice system often mixes logical and practical impossibility:
Creating a perfect justice system might be seen as logically impossible if it involves inherent contradictions.
- Confusion from Entanglement of Different Notions of Impossibility: The entanglement of different notions of impossibility can lead to significant confusion in philosophical, scientific, and everyday discussions.
- Logical vs. Practical Impossibility: The entanglement of different notions of impossibility can create misunderstandings and hinder productive discussions.
- Central distinction: A Taxonomy of Impossibilities helps separate what otherwise becomes compressed inside A Taxonomy of Impossibilities.
- Best charitable version: The idea has to be made strong enough that criticism reaches the real view rather than a caricature.
- Pressure point: The vulnerability lies where the idea becomes ambiguous, overextended, or dependent on background assumptions.
What ties this page together.
A good route is to identify the strongest version of the idea, then test where it needs qualification, evidence, or a neighboring concept.
The main pressure comes from treating a useful distinction as final, or treating a local insight as if it solved more than it actually solves.
Keep Types of Impossibility, Nested Order, and Other Significant Types of Impossibility in the same frame. That is what shows what the page is claiming, where it gets tested, and what would have to change if the claim is right.
Read this page as part of the wider Metaphysics branch: the prompts point inward to the topic, but they also point outward to neighboring questions that keep the topic honest.
- How does physical impossibility differ from logical impossibility?
- Why is faster-than-light travel considered physically impossible?
- What confusion might arise from entangling logical and metaphysical impossibility in a debate about the nature of God?
- Which distinction inside A Taxonomy of Impossibilities is easiest to miss when the topic is explained too quickly?
- What is the strongest charitable reading of this topic, and what is the strongest criticism?
Deep Understanding Quiz Check your understanding of A Taxonomy of Impossibilities
This quiz checks whether the main distinctions and cautions on the page are clear. Choose an answer, read the feedback, and click the question text if you want to reset that item.
Future Branches
Where this page naturally expands
Nearby pages in the same branch include Metaphysics – Core Concepts, What is Metaphysics?, Ontological Domains, and Dualism vs Materialism; those links are not decorative, but suggested continuations where the pressure of this page becomes sharper, stranger, or more usefully contested.