, QUESTION 1:
Martin Luther King Jr.’s pronouncement advocates the natural law approach to legal philosophy.
Natural law theory posits that the validity of positive law (man-made law) depends on its
conformity to a higher moral order derived from universal principles of justice, reason, or divine
will. King’s distinction between “just” and “unjust” laws directly reflects the core natural law tenet
that an unjust law is not a true law in the fullest sense (lex injusta non est lex). He asserts a moral
duty to obey just laws but a moral responsibility to disobey unjust ones, thereby subordinating
legal obligation to moral obligation.¹
Origin and Development of Natural Law Theory:
Ancient Origins: The foundational idea emerged in ancient Greece. Aristotle (384–322 BCE)
distinguished between natural justice (physei dikaion), which has the same validity everywhere,
and conventional justice (nomikon), which varies.² Later, the Stoics developed the concept of a
universal logos (rational principle) governing nature and human conduct.
Roman Development: Cicero (106–43 BCE) articulated natural law as “right reason in
agreement with nature,” applicable to all peoples and unchangeable by statute.³ This idea
influenced Roman legal thought, though it remained largely philosophical.
Medieval Christian Synthesis: Thomas Aquinas (1225–1274 CE) systematised natural law theory.
He distinguished four types of law: eternal (God’s rational plan), natural (human participation in
eternal law through reason), human (positive law), and divine (Scripture). Aquinas famously
argued that any human law conflicting with natural law is “a perversion of law” and need not be
obeyed in conscience.⁴
Early Modern Secularisation: Hugo Grotius (1583–1645) argued that natural law would remain
valid “even if we were to suppose that God does not exist” (etsi Deus non daretur), laying
groundwork for secular natural rights theories.⁵ John Locke (1632–1704) used natural law to
justify resistance against unjust government, profoundly influencing revolutionary thought.
Footnotes:
¹ Martin Luther King Jr., “Letter from Birmingham Jail” (16 April 1963), in Why We Can’t Wait (New York: Harper & Row, 1964), 77–78.
² Aristotle, Nicomachean Ethics, trans. W. D. Ross (Oxford: Clarendon Press, 1925), Book V, ch. 7, 1134b18–35.
³ Cicero, De Re Publica [On the Republic], trans. C. W. Keyes (Cambridge, MA: Harvard University Press, 1928), Book III, ch. 22, 211.
⁴ Thomas Aquinas, Summa Theologica, trans. Fathers of the English Dominican Province (New York: Benziger Bros., 1947), I–II, Q. 95, Art. 2 (“Human law is
law only in virtue of its accordance with right reason… every law made by man has the character of law to the extent that it is derived from the natural law.
But if it deviates in any way from the natural law, it is no longer a law but a corruption of law.”).
⁵ Hugo Grotius, De Jure Belli ac Pacis [On the Law of War and Peace], trans. F. W. Kelsey (Oxford: Clarendon Press, 1925), Prolegomena, para. 11
Martin Luther King Jr.’s pronouncement advocates the natural law approach to legal philosophy.
Natural law theory posits that the validity of positive law (man-made law) depends on its
conformity to a higher moral order derived from universal principles of justice, reason, or divine
will. King’s distinction between “just” and “unjust” laws directly reflects the core natural law tenet
that an unjust law is not a true law in the fullest sense (lex injusta non est lex). He asserts a moral
duty to obey just laws but a moral responsibility to disobey unjust ones, thereby subordinating
legal obligation to moral obligation.¹
Origin and Development of Natural Law Theory:
Ancient Origins: The foundational idea emerged in ancient Greece. Aristotle (384–322 BCE)
distinguished between natural justice (physei dikaion), which has the same validity everywhere,
and conventional justice (nomikon), which varies.² Later, the Stoics developed the concept of a
universal logos (rational principle) governing nature and human conduct.
Roman Development: Cicero (106–43 BCE) articulated natural law as “right reason in
agreement with nature,” applicable to all peoples and unchangeable by statute.³ This idea
influenced Roman legal thought, though it remained largely philosophical.
Medieval Christian Synthesis: Thomas Aquinas (1225–1274 CE) systematised natural law theory.
He distinguished four types of law: eternal (God’s rational plan), natural (human participation in
eternal law through reason), human (positive law), and divine (Scripture). Aquinas famously
argued that any human law conflicting with natural law is “a perversion of law” and need not be
obeyed in conscience.⁴
Early Modern Secularisation: Hugo Grotius (1583–1645) argued that natural law would remain
valid “even if we were to suppose that God does not exist” (etsi Deus non daretur), laying
groundwork for secular natural rights theories.⁵ John Locke (1632–1704) used natural law to
justify resistance against unjust government, profoundly influencing revolutionary thought.
Footnotes:
¹ Martin Luther King Jr., “Letter from Birmingham Jail” (16 April 1963), in Why We Can’t Wait (New York: Harper & Row, 1964), 77–78.
² Aristotle, Nicomachean Ethics, trans. W. D. Ross (Oxford: Clarendon Press, 1925), Book V, ch. 7, 1134b18–35.
³ Cicero, De Re Publica [On the Republic], trans. C. W. Keyes (Cambridge, MA: Harvard University Press, 1928), Book III, ch. 22, 211.
⁴ Thomas Aquinas, Summa Theologica, trans. Fathers of the English Dominican Province (New York: Benziger Bros., 1947), I–II, Q. 95, Art. 2 (“Human law is
law only in virtue of its accordance with right reason… every law made by man has the character of law to the extent that it is derived from the natural law.
But if it deviates in any way from the natural law, it is no longer a law but a corruption of law.”).
⁵ Hugo Grotius, De Jure Belli ac Pacis [On the Law of War and Peace], trans. F. W. Kelsey (Oxford: Clarendon Press, 1925), Prolegomena, para. 11
