QuestionsWhat is a just society?Injustice anywhere is a threat to justice everywhere
What is a just society?One humanity

Injustice anywhere is a threat to justice everywhere

The network of mutuality; 'Injustice anywhere...'

Martin Luther King Jr. 1929 · 1968Minister and leader of the civil rights movement: he defends nonviolent disobedience to unjust laws, openly and accepting the penalty.
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What it claims

'Injustice anywhere is a threat to justice everywhere': justice is owed to all, and no one is an outsider where it is violated.

Why

We are caught in a network of ties that no one can leave: what affects one affects all, so no one is an outsider where injustice is.

The same idea through history
Martin Luther King Jr.1963Martin Luther King answers from his cell eight Alabama clergymen (seven Christian ministers and a rabbi) who judged him an 'outsider' and criticised his demonstrations. He explains why he is in Birmingham.
In short

"Injustice anywhere is a threat to justice everywhere" is an argument by Martin Luther King Jr. (Letter from Birmingham Jail (16 April 1963), 1963) on the question "What is a just society?" (answer: one humanity). Its claim: 'Injustice anywhere is a threat to justice everywhere': justice is owed to all, and no one is an outsider where it is violated. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P3). AskPhilosophy presents 3 objections, 1 of them with a documented reply, and the original text behind each premise, checked word for word.

Letter from Birmingham Jail (16 April 1963)
Valid with an implicit premise

In April 1963 King is arrested in Birmingham, Alabama, after a demonstration against segregation. Eight white clergymen of the region have published a statement calling him an outside agitator. He answers that no one can be a stranger to injustice: communities and states are tied together, and what affects one affects all. The duty of justice therefore does not stop at the borders of a city, a state or a race. It is an argument for a justice addressed to everyone, not limited to those in our own group.

P1All communities and states are interrelated: 'We are caught in an inescapable network of mutuality, tied in a single garment of destiny.'
P2In such a network, whatever affects one directly affects all indirectly.
P3 · implicit premiseIf an injustice indirectly affects every member of the network, each has a reason and a duty to oppose it, wherever it occurs.
Therefore 'Injustice anywhere is a threat to justice everywhere': justice is owed to all, and no one is an outsider where it is violated.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Valid with P3. P1 and P2 describe a world where everything is tied together. P3, hidden, links this fact to a duty. Points of attack: P1 (is the link real in every case, or only for closely interwoven societies like the United States in 1963?) and P3 (is this duty limited, or does it demand attending to every injustice in the world?). King first addresses his fellow citizens: 'Anyone who lives inside the United States can never be considered an outsider anywhere within its bounds.'
Analogy. A thread in a knitted garment: if one stitch drops somewhere, the whole garment slowly unravels. No one can say the stitch at the end is not their business.

Objections

3

Each objection is a conversation: click to see who replies and where the debate stands.

T
The eight Alabama clergymen 1963 · attacks the conclusion

In their statement 'A Call for Unity' (12 April 1963) they acknowledge injustices but say the struggle should be conducted in the courts and by local negotiation, and they regret that demonstrations are led by 'outsiders'. For them King's urgency stirs up tension.

a defender replies
Martin Luther King defender of the argument · 1963
King answers that he did not come from nowhere: he was invited, he has organisational ties there, and above all 'I am in Birmingham because injustice is here'.
Where the debate stands (our summary)The clergymen: the struggle is local and judicial. King: injustice has no border. Core disagreement: who has the standing to intervene in an injustice that is not their own?
Alasdair MacIntyre 1984 · attacks premise 3

MacIntyre argues, in 'Is Patriotism a Virtue?', that morality is always lived within particular communities and that our first duties go to them. A duty of justice without belonging, owed to all alike, risks being a mere abstraction.

no reply
No reply possible: objection raised in 1984, after the author's death (1968).
The debate goes on (our summary) Reconstructed reply: King does not abandon belonging, he widens it. For him, black and white Americans are members of the same national community, whose Constitution promises equality (our reading). The debate stays open on the extent of the community: a nation, or all humanity?
Where the debate stands (our summary)MacIntyre: our duties come first from particular communities. King: the network has no edge. Core disagreement: where does the community one is responsible for end?
Susan Wolf 1982 · attacks premise 3

In 'Moral Saints', Wolf argues that a life wholly devoted to moral good, like a saint's, leaves no room for the personal projects that make a life good: moral perfection is not an ideal one should want. Applied here (our reconstruction, Wolf does not target King): a duty to fight injustice everywhere would be of that kind.

no reply
No reply possible: objection raised in 1982, after the author's death (1968).
The debate goes on (our summary) Reconstructed reply: King himself limits the duty by real ties: being invited, having connections (see above). The text does not ask us to attend to everything, but not to call ourselves strangers to what is near and known (our reading).
Where the debate stands (our summary)Wolf: an unlimited duty is unliveable. King: duty follows real ties. Core disagreement: what is the reasonable measure of the duty of justice?