Why Should Japan’s Emperor Remain Patrilineal?
Not because men are superior, but because no one should get to choose the Emperor
Patrilineal succession cannot be justified by differences in ability between men and women, or by the Y chromosome. If there is still a reason to preserve it, perhaps that reason is not to select the person best suited to be Emperor, but to prevent us from selecting an Emperor according to our preferences. Hume, Weber and Oakeshott illuminate the meaning of this ‘irrational boundary.’
The “male in the male line” rule survived reform
On July 17, 2026, Japan’s Diet enacted amendments to the Imperial House Law intended to secure the number of Imperial Family members. The law was promulgated on July 24.
The amendments allow Imperial princesses to retain royal status after marriage and permit male-line descendants of the eleven former collateral branches of the Imperial Family to be adopted into the family. Yet Article 1 of the Imperial House Law, which limits succession to “a male offspring in the male line belonging to the Imperial Lineage,” remains unchanged. House of Representatives, “Bill to Amend the Imperial House Law and Related Acts”; e-Gov, Imperial House Law
A legislative agreement reached shortly before the bill likewise confirmed that the present line of succession—from Emperor Naruhito to Crown Prince Akishino and then Prince Hisahito—should not be disturbed. At the same time, it called for continued consideration of how to secure stable succession after Prince Hisahito. Summary by the presiding officers of both houses, June 10, 2026
The debate has not ended.
If anything, the reform forces us to ask the question again.
Why should the imperial line remain patrilineal?
“Patrilineal” and “male-only” are not the same
We must begin by distinguishing a female Emperor from a matrilineal Emperor.
Patrilineal succession traces descent through a person’s father, the father’s father and so on until it reaches a previous Emperor. It is therefore logically possible for a woman in the male line to become Emperor.
Japan has in fact had eight female sovereigns across ten reigns, including Emperors Suiko, Jitō, Genmei, Genshō and Kōken. All were women descended from the imperial line through their fathers. Advisory Council Report on the Imperial House Law, held by the National Diet Library
A matrilineal Emperor, by contrast, would descend from an Emperor through the mother but not through the father.
The present system therefore contains two separate restrictions.
One is a male-only rule, under which a woman cannot accede to the throne.
The other is a patrilineal rule, under which succession depends on descent through the father’s line.
When these restrictions are collapsed into a single argument about “sex discrimination versus tradition,” the central issue disappears.
It is possible to abolish the male-only rule and recognize a female Emperor while preserving patrilineal descent as the principle that defines the dynasty.
The Y chromosome cannot justify patrilineal succession
Defences of the male line sometimes invoke the Y chromosome.
Because a man inherits his Y chromosome from his father, the argument runs, men in the imperial male line carry a Y chromosome transmitted from past Emperors.
But this claim weakens rather than strengthens the case for patrilineal succession.
Imperial legitimacy has never been certified by genetic testing. The Y chromosomes of successive Emperors have not been scientifically verified, and a female Emperor does not possess a Y chromosome at all.
Yet Japan’s historical female Emperors are not regarded as having left the imperial lineage.
The imperial line is not a piece of biological material.
It is an institutional relationship constituted by genealogy, ritual, law, social recognition and memory carried from one generation to the next.
Nor can the rule be defended by claiming that men are better rulers. Under Japan’s present Constitution, the Emperor is not a political ruler but “the symbol of the State and of the unity of the People.” The historical existence of female Emperors also makes it impossible to argue that a woman cannot perform the role.
If there is a reason to preserve the male line, it is not that the male body is superior.
It may instead be that patrilineal descent has nothing to do with ability or popularity.
The Emperor is not a job for “the best person”
Politicians, researchers and athletes are selected.
We assess ability and achievement and choose the person considered most suitable for a role. Selection is often unfair in practice, but its stated aim is at least to identify the more capable candidate.
The Emperor is not such an occupation.
No one becomes Emperor by passing an examination. There is no election for national popularity, and no candidate can volunteer for the position.
That may appear to be an undemocratic defect.
But it is possible to see the arrangement in reverse.
In a democracy, the people choose those who exercise political power. Perhaps that is precisely why a symbol without political power should not be placed in the same competition.
If the Emperor were selected for competence, character, popularity or conformity with contemporary values, comparisons among candidates would begin.
Who is most liked by the public?
Who is best suited to diplomacy?
Who embodies a “new Japan”?
At that moment, imperial succession would become an election without ballots.
Citizens, media outlets and political parties would each begin promoting the Imperial Family member they considered most suitable. Even if that person said nothing political, others could turn them into a political standard-bearer.
The first meaning of patrilineal succession is not that it selects an excellent man.
It is that it deliberately denies us the right to choose the Emperor.
Weber: do not turn a symbol into a popularity contest
Max Weber distinguished three ideal types of authority according to the grounds on which people accept it: traditional, charismatic and legal-rational authority.
Traditional authority rests on continuity—on the fact that something has long been done in a particular way. Charismatic authority arises from a person’s exceptional appeal or ability. Legal-rational authority rests on confidence in laws and procedures. Stanford Encyclopedia of Philosophy, “Political Legitimacy”
Government in contemporary Japan is conducted through legal institutions: the Diet, the Cabinet and the courts. The Emperor has no powers related to government.
For the symbolic monarchy to remain relatively stable, the Emperor must therefore avoid competing for the same kind of legitimacy as politicians.
If an Emperor gained the position through personal appeal or national popularity, the office would approach charismatic authority. Place a popular Emperor beside an unpopular government, and the symbol could easily become a rival source of political authority.
If the throne is inherited irrespective of the occupant’s ability or opinions, however, an Emperor cannot claim: “The people selected me, so I am entitled to lead them.”
The irrationality of heredity deprives the Emperor of the language of political self-justification.
Here lies a strange paradox.
Hereditary succession is not democratic. Yet by placing the Emperor outside democratic competition, it prevents the throne from competing with democratic government.
Hume: conventions do not endure because they are “correct”
But even if succession is hereditary, why could it not be matrilineal?
Absolute primogeniture would not create a popularity contest either. This objection is correct.
The principle of “not choosing the Emperor” explains heredity, but it does not by itself explain patrilineal descent.
We must therefore consider the value of convention.
David Hume explained institutions such as property, promises and government through conventions that arise before people ever sign an explicit social contract.
When two people row the same boat, they do not need to negotiate a contract before every stroke. But the boat will not move unless each adjusts to the other. A convention is not a correct answer written into nature. It is a pattern of common action that each person can follow because they expect others to follow it too. Stanford Encyclopedia of Philosophy, “Convention”
Natural science cannot tell us whether patrilineal or matrilineal succession is correct.
We can trace fathers, mothers or both.
Had Japan’s Imperial House consistently descended through women, the same argument would support preserving the female line.
The reason to maintain the patrilineal line is not that it is universally right.
It is that this line has already been drawn and has sustained a shared understanding over a long period that “the same imperial lineage continues.”
Just as the value of money does not reside in the material of a banknote, the value of patrilineal succession does not reside inside the male body.
It resides in shared time: in generations of people recognizing the same genealogy as the imperial line.
Other rules of succession could also function as institutions.
But changing the rule would not merely enlarge the pool of candidates. It would alter the definition of what counts as the continuation of the same dynasty.
Change is not impossible.
The point is that what change would lose should not be assigned a value of zero by dismissing it as mere superstition.
Oakeshott: tradition is a practice, not a blueprint
Michael Oakeshott criticized rationalism in politics and argued that knowledge includes not only “technical knowledge” that can be written down, but also practical knowledge acquired by participating in a tradition.
An institution is not a machine that can be designed from scratch by listing its aims and effects. Over time it develops unwritten habits, restraints, symbols and distances between itself and the public. Stanford Encyclopedia of Philosophy, “Michael Oakeshott”
The Imperial House is not constituted by the text of the Imperial House Law alone.
It also depends on what an Emperor does not say.
How far the institution remains from political conflict.
When citizens become conscious of the Emperor.
How members of the Imperial Family are prepared for public duties.
The accumulated practice of these things sustains Japan’s symbolic monarchy.
Patrilineal descent is a thin thread running through that practice.
The thread has no scientific force. But we cannot prove in advance that cutting it would leave the entire fabric exactly the same.
Oakeshott’s argument does not make tradition absolute. Traditional knowledge can be mistaken, and mere longevity cannot justify discrimination or suffering.
Those who change an institution nevertheless bear a burden of explanation.
It is not enough to show that a new arrangement is equal in the abstract. They must also explain how the Imperial House will maintain its distance from political competition after the change.
Preserving the male line must not symbolize male supremacy
Any defence of patrilineal succession must meet a serious condition.
It must not communicate that men are more worthy than women.
The male line is a boundary confined to the exceptionally narrow institution of imperial succession. It is not a principle that can justify male dominance in politics, employment, education or family life.
If we distinguish a female Emperor from a matrilineal Emperor, granting succession rights to a woman in the male line is not necessarily inconsistent with preserving patrilineal descent.
There is no need to treat the rule “a woman cannot become Emperor” as the essence of the male line.
Still more important are the lives of individual members of the Imperial Family.
No particular person should be required to marry or have children in order to preserve the patrilineal line. The moment “giving birth to a boy” becomes an individual duty, tradition ceases to be an institution that protects human beings and becomes a mechanism that consumes them as material for the institution.
The male line may have value worth preserving.
But it is not an absolute value to be maintained at the expense of a person’s freedom and dignity.
The imperial throne itself, under Article 1 of the Constitution, derives its position “from the will of the people with whom resides sovereign power.” If the male-line convention loses public understanding, imposes unbearable burdens on the Imperial Family and makes succession impossible, it will have forfeited its own public function. e-Gov, Constitution of Japan
To preserve a tradition is not to force precisely the same form to continue whatever happens.
It is to understand why the tradition existed and to let it change without destroying that purpose.
The male line is not a “right,” but a boundary that keeps the Emperor empty
The strongest justification for the male line is neither purity of blood nor male superiority.
It is that the Emperor should not be selected for ability, popularity or ideology.
In democratic politics, citizens choose who should exercise power.
In a symbolic monarchy, the majority of a particular era does not choose who it would prefer as the symbol.
The historical boundary of patrilineal descent makes it harder for us to project our current ideal of a person onto the Imperial House and politically sort its members.
In that sense, the rule does not elevate the most excellent person.
It prevents anyone from saying, “I became Emperor because I am superior.”
Precisely because the male line is irrational, no claim of personal superiority can be derived from it.
And because the office remains empty of that claim, politicians can compete over policy while citizens retain their position as the sovereign power that chooses politics.
If there is a reason why the Emperor should remain patrilineal, it is not to make men a special class of human beings. It is to prevent the Emperor from becoming a special political personality selected by someone.
This question
Would allowing the public to choose its ideal Emperor democratize the institution?
Or would it force a symbol that is supposed to lack political power into a new contest for popularity?
If we abolish the irrational convention of the male line, do we remove discrimination alone?
Or do we also lose another irrational arrangement: a symbol chosen by no one?
References
- e-Gov, Constitution of Japan
- e-Gov, Imperial House Law
- House of Representatives, “Bill to Amend the Imperial House Law and Related Acts”
- Summary of the legislature’s response by the presiding officers of both houses
- Advisory Council Report on the Imperial House Law, National Diet Library
- Stanford Encyclopedia of Philosophy, “Convention”
- Stanford Encyclopedia of Philosophy, “Political Legitimacy”
- Stanford Encyclopedia of Philosophy, “Michael Oakeshott”
Facts were checked as of August 6, 2026. The philosophers cited here did not directly address Japanese imperial succession; this essay applies their theories to the question.