—Ethics from Estoppel (EE)—
The estoppel is the following concept:
Bob punches Alice, so now if Alice punches Bob back, if Bob tries to object to Alice punching, he contradicts himself, because Bob already set the norm that punching is justified.
Bob, by punching, is said to be 'estopped' from objecting to Alice's self-defense.

Some right-libertarians, specifically Hoppeans, argue such an estoppel implies the Non-Aggression Principle. This intuition is incorrect, because it assumes one action involving force is necessarily equivalent to any other action involving force.
That claim is only true if the NAP is true, thus it is begging the question.

Instead, we can think of the Estoppel as a measure of whether a coercive claim can be justified. Whenever a person invokes force, or any semblance of obligation upon others, including negative obligation, they advance a claim about what others may do, a claim about what others may be prevented from doing, or a claim about whose interests may be protected or overridden.

We can then think of this as the measure of whether it is justified or whether the actor in a situation is 'estopped' aka their justification can survive when the people involved are treated as interchangeable. If it cannot, then the claim defeats itself. This will be defended shortly.
The NAP is thus not the foundation of estoppel, but one possible consequence.

We will now argue that the acceptance of the estoppel as normatively binding, derives the Anti-Abuse Principle of Yoggism, that actions inherently frustrating and constituting intrinsic subordination of interests, are illegitimate.


—Estoppel Begins with Consistency—
The original case of punching, of violent aggression, reveals the first requirement for the estoppel.
An aggressor initiates force against another person, and when defensive force is used in response, the aggressor objects.

This aggressor's position contains two incompatible claims.
His action asserts that force is permissible under these circumstances, while his objection asserts similar force is impermissible under the same circumstances.
The aggressor attempts to reject the principle that his own action has already asserted, this is the source of the inconsistency of the objection.

However, this alone reveals a limitation in how the estoppel is used.


—The Problem of Special Pleading—
What if the aggressor simply claims, "Only I have the right to use force under these circumstances"? This claim may be internally consistent, but that causes the estoppel to stop working entirely.
If another person uses identical force against them, they suddenly can object because their new principle distinguishes between persons, granting them special privilege.

Following this logic, anyone could claim "my group may rule another group, uninhibited" and get off scot-free.
If this special pleading were sufficient, estoppel would no longer distinguish between justified and unjustified coercion. Any person could escape estoppel merely by defining themselves as uniquely immune to objection.
An account of estoppel that permits such arbitrary privilege is not an account of estoppel at all.

A true estoppel, and a true grounding of self-defense in the estoppel, is thus required to recognize that a justification needs to not just be consistent but also be valid independently of who happens to benefit from it. This is interchangeability, of persons.

This requirement is necessary and becomes clear as such through proportional defense.
Because estoppel is traditionally used to justify proportionate self-defense, it necessarily presupposes some criterion for determining when two claims are comparable.

Consider this question: "When are two conflicting claims similar enough that they should be evaluated under the same principle?"
There must be an answer to this question, otherwise proportionality has no coherent meaning.
The answer cannot simply be when two claims are identical in every way including subject.


—Estoppel Implies Interchangeability—
Imagine a disabled person stuck in a wheelchair. Due to his disability, he is unable to restrain or otherwise thwart a trespasser with an ordinary use of force, instead his only practical means of resistance may be limited to verbal objection and the use of a firearm within his reach.

Now imagine a drunk homeless person enters his home at night and begins stealing food from his refrigerator. To argue the disabled person is not allowed to use lethal force at all because the trespassers' life is worth more than the disabled person's property, is to deny the disabled person any property rights at all, simply due to his physical limitations.
The principle becomes: "A person's rights depend on their abilities"

This is not a self-defense right, and libertarians would immediately object to this and call this use of the estoppel invalid. The reason ultimately comes back to interchangeability of persons.
Just because the disabled person is disabled, doesn't change what claims are inconsistent to object to. If we apply interchangeability, this problem goes away.

Looking at interchangeability, if the positions were exchanged, the able-bodied person would not accept a rule that reduced his own rights merely because he occupied a disabled person's position.
Likewise, the intruder could not consistently object to the disabled person's defense while claiming that, if he were in the disabled person's position, he would still reject being denied the only effective means of protection.
If proportionality is not evaluated according to interchangeable claims, then the disabled person's rights become contingent upon his physical abilities rather than the principle being defended.

Proportionality itself becomes position-dependent, contradicting the reciprocal structure estoppel requires. Without interchangeability, the estoppel cannot distinguish between genuine justification and arbitrary privilege.
Any contradiction can always be avoided by assigning oneself a special exemption.

Therefore, proportionality cannot be determined by comparing physical acts alone. It must compare the competing justifications, by looking at claims, not the specific subjects of a justification.
This is precisely what interchangeability requires.


—Reciprocity, Interests, and the Structure of Claims—
Interchangeability reveals a deeper requirement. A difference between people can matter only if the reason for treating them differently survives exchanged positions.

Otherwise, the difference is reduced to a mere basis for privilege, violating interchangeability.
Once it is established that justifications must survive interchangeable positions for self-defense rights to apply via estoppel, reciprocity follows for the estoppel too.

A person cannot demand a principle for others that they would reject if they occupied the other position.
This does not imply all interests have equal priority though, what it does imply is that every person's interests must be capable of counting as reasons within the justification, which is equal standing, not equal result.
Every normative claim implicitly advances some account of which interests are protected, restricted, or overridden.
Bodily rights claims protect interests in physical security, property claims protect an interest in specific resources and objects, contract claims protect people's ability to communicate and act upon their own interests with others cooperatively.

Whenever force is invoked against a person, one person's interests are being protected against competing interests.
The actual question is, "Is this conflict resolved by a principle that can be accepted from either side, or does it depend upon one side being inherently privileged?"


—Subordination violates Interchangeability—
The truth derived from the estoppel is that not every property claim is automatically justified by someone claiming ownership over something.

Suppose a property owner claims that ownership alone automatically settles every conflict of interests involving that property. Such a case would fail interchangeability, it is the same special pleading as previously described, and creates the same problem relative to the estoppel. This logic can be taken further.

Consider a racist landlord who wants to evict a tenant simply for being black. The lease doesn't explicitly say the landlord can do that, but he wrote into the lease that he has the final say.
The relevant claim is not merely: "I wish to control my property".

That claim may be compatible with a general principle of ownership, but the claim is so general that it fails the aforementioned interchangeability. We must actually discuss the relevant claim at hand, and this claim coems out to be:
"My interest in racial exclusion overrides your interest in equal participation."
This claim violates interchangeability. Exchange races, suppose the landlord was black and the excluded tenants were white, and the justification immediately collapses.

The person defending exclusion would not accept the principle if they occupied the excluded position, the problem is therefore not property ownership itself but rather that the justification inherently subordinates one person's interests to another.
Such a claim defeats itself through estoppel.


—Intrinsic Subordination—
The estoppel does not imply all differences between people are illegitimate. Rather, different roles can be justified based on knowledge and claims of justified authority, a doctor may have limited authority in the context of medicine because the distinction rests on expertise and consent, a parent may have limited authority over a child due to the relationship involving responsibility and dependency, a property owner may have limited authority over a resource if the justification for that authority passes reciprocal evaluation.

A legitimate distinction is based on a reason that remains valid when positions are exchanged.
An illegitimate distinction is one whose justification depends upon assigning one person's interests inherently greater justificatory standing than another's.
The estoppel argument rejects the second distinction.


—Deriving the Anti-Abuse Principle—
The examples demonstrate the same underlying failure, the problem is not that interests conflict, as such conflict is avoidable. It is also not merely that outcomes differ, different outcomes may arise from legitimate reasons.

The problem is a specific type of coercive justification:
"A justification where the frustration of another person's interests is not merely an effect of the rule, but part of what the rule is fundamentally doing."

In such cases, the action or institution does not merely create an unequal result, but requires another person's interests be treated as having inferior standing in the justification itself. The frustration is built into the principle being defended.

The frustration of interests is not an accidental consequence of applying the norm, but rather a part of what the norm itself is built to accomplish.
Thus, from a correct account of estoppel, we derive the Anti-Abuse Principle of Yoggism:


—The Anti-Abuse Principle (AAP)—
Actions that are intrinsically frustrating to another's non-abusive fulfillment of interests, or inherently subordinate another's interests, constitute abuse, and are thus illegitimate.
Actions that proportionately defend against abuse, or inhibit conduct that is inherently frustrating of interests, are legitimate insofar as they constitute self-defense.


—Conclusion—
The use of "inherent" means the frustration of interests is intrinsic to the content and justification of the action itself, not merely an external consequence that isn't generalizable.

An action violates this principle when defending it requires saying: "this person's interests count less because this person occupies X position".
Such a claim cannot survive interchangeability, it cannot satisfy reciprocity.
Thus, such a claim defeats itself through the estoppel.

This estoppel argument does not only apply after rights are established, instead it can be used to derive rights through the AAP. Assuming rights to apply the estoppel to is begging the question and risks self-contradiction.
Rights are themselves claims, claims that face a justificatory burden when it comes to whether using force or otherwise to defend such rights is justified. That is not exempt from the estoppel.

To accept the estoppel as normative for justifying self-defense rights, thus implies some semblance of reciprocity such that the Anti-Abuse Principle is a consequence.
An action inconsistent with the AAP thus cannot be defended via estoppel.


—Universal Application—
The estoppel argument applies whenever a coercive claim is made against a sentient being whose interests are such that the claim's justification can be meaningfully evaluated.
For example, we can take the original example at the onset and reuse it with a non-human animal.

Bob punches a dog, so now if the dog hits Bob back, Bob loses the ability to consistently make a claim against the hit, because Bob already set the norm that hitting is justified.
Bob, by punching, is said to be 'estopped' from objecting to the dog's self-defense.

Any argument that Bob being a special species is a direct recreation of the interchangeability problem from before, creating the same problem as saying Bob is a special sex or Bob is a special person who has the right to punch anyone but nobody else is allowed to punch him.

Suppose Bob claims humans may abuse dogs because they are humans. If positions are exchanged by species, Bob would no longer accept the principle. The justification thus depends on which party occupies the privileged role rather than upon a reciprocal reason.
This violates interchangeability.

If defensive force is justified because the coercive claim fails estoppel, then that failure does not depend on who performs the defensive act. The same failed justification may thus be resisted by third parties acting to defend the victim.

Therefore, accepting the dog has the right to defend themselves, also implies via estoppel that other beings, including other humans, are allowed to defend the dog from unjustified transgressions.
The estoppel therefore is not restricted to human beings. It applies whenever there exists a sentient being whose interests are capable of being the object of a coercive claim that can be said to be justified or unjustified.

A being need not consciously formulate moral arguments for this to be true, rather it is enough that the being possesses interests and preferences such that it is meaningful to ask whether another person's claim against those interests is justified.

If it is meaningful to evaluate a claim against a being as justified or unjustified,  that abuse against them is unjustified, or that it is inconsistent to object to that being's proportionate defense, then estoppel already applies. Restricting estoppel only to members of a particular species would simply recreate the same arbitrary privilege that interchangeability rejects.


—The Absolute Interest Conclusion—
This directly implies by the estoppel that animal cruelty is unjustifiable and impossible to consistently defend. If we accept animal cruelty as unjustifiable this implies a human attacking another human for abusing an animal, is justified, and if the animal abuser pulls out a weapon, the other human gains the right to defend themselves with lethal force.
This implies humans have the right to defend animals from other humans with lethal force.

If every sentient being possesses interests that cannot be assigned lesser justificatory standing merely because of species or other arbitrary classification, then ethical justification must treat the recognition of the value of their interests as universal.

From this we derive the Absolute Interest Conclusion:
It is utmost rational to uphold the fulfillment of interests of all sentient beings, across all possible reference frames; with priority to existent, rational, inherent interests, as a value.
This conclusion is not an optimization principle, but an upholding of interests as a value.


—The Problem with Utilitarianism vs. Principles—
This also functions as an argument against Utilitarianism and similar consequentialist arguments. Under Utilitarianism, in an isolated circumstance, we are forced to conclude that if a human attacks an animal, they must not be stopped with lethal force, because killing a human is worse than killing an animal at least if the animal will have a shorter lifespan than the human.

Estoppel Ethics goes in direct contradiction of this by claiming based on principle, that consequences are not the end all be all of ethics, and animal rights are derived from principle.
Thus even in a isolated circumstance, killing a human to defend an animal is justified if necessary.


–Deduction of Estoppel Ethics–
–Definitions:
(Estoppel): A person is estopped when they cannot consistently object to a principle that their own conduct has already asserted.
(Proportionality): The requirement that a defensive response bear an appropriate relationship to the conduct it answers.
(Right): A right is a guaranteed permission that an action, interest, or property is justified, together with the normative validity of defending it as necessary.

–Premises:
(P1): Estoppel rejects any justification that requires a special exemption from the principle it invokes.
(P2): Estoppel grounds the justified self-defense of existing rights.
(P3): Differences in physical ability can prevent equally situated persons from using equivalent defensive acts or escalating force in the same manner.
(P4): Any account of proportionality that denies self-defense rights solely because of physical ability or social position undermines the rights estoppel is meant to justify.
(P5): Estoppel evaluates whether the claims involved in coercive conflicts are justified.
(P6): A coercive justification inherently subordinates another person's interests when it gives those interests lesser justificatory standing solely because of that person's position.
(P7): A coercive action is legitimate only if its justification survives estoppel.

–Logic:
(L1): From (P2 + P4), if estoppel grounds rights, then proportionality cannot deny self-defense rights solely because of physical ability or social position.
(L2): From (L1 + P3), proportionality cannot be determined solely by comparing equivalent physical acts, because physical differences would make the availability of self-defense depend upon ability.
(L3): From (P2 + L2), the standard used to determine proportionality must preserve the justified self-defense of rights rather than depend upon differences in physical ability.
(L4): From (P5 + L3), proportionality must evaluate the justification of defensive actions rather than merely the physical equivalence of those actions.
(L5): From (P1 + L4), a justification that depends only upon who holds a position rather than independent reasons supporting the position implies a special exemption and fails estoppel.
(L6): From (P6 + L4), a coercive justification that inherently subordinates interests depends upon treating one person's interests as having lesser justificatory standing because of their position.
(L7): From (L5 + L6), coercive justifications that inherently subordinate interests fail estoppel because they rely on position-dependent standards.
(L8): From (L7 + P7), coercive actions based on inherently subordinating justifications are illegitimate, while proportionate resistance to such conduct is legitimate.

–Conclusion:
From (L6 + L7): Therefore, actions that inherently subordinate another person's interests are illegitimate, while proportionate resistance to such conduct is legitimate as self-defense.