Johannes Althusius (1563 – August 12, 1638)^[1] was a German-French jurist and Calvinist political philosopher.

He is best known for his 1603 work, "Politica Methodice Digesta, Atque Exemplis Sacris et Profanis Illustrata".^{[lower-alpha 1]} revised editions were published in 1610 and 1614. The ideas expressed therein relate to the early development of federalism in the 16th and 17th centuries and the construction of subsidiarity.

Althusius was born in 1563, to a family of modest means in Diedenshausen, County Sayn-Wittgenstein (Siegen-Wittgenstein),^[1] a Calvinist County in what is now the state of North Rhine Westphalia (but was then the seat of an independent Grafschaft or County). Under the patronage of a local count, he attended the Gymnasium Philippinum in Marburg from 1577 and began his studies in 1581, concentrating in law and philosophy. He first studied Aristotle in Cologne, then studied law around 1585/86 under Denis Godefroy at Basel.^[2] In 1586, Althusius received his doctorate in civil and canon law from the University of Basel. While studying at Basel, Althusius lived with Johannes Grynaeus for a period of time, with whom he studied theology.^[2]

After completing his studies, in 1586 Althusius became the first professor of law at the Protestant-Calvinist Herborn Academy of Nassau County.^[2] From 1592 to 1596, he taught at the Calvinist Academy in Burgsteinfurt/Westphalia.^[1] He was married in 1596 in Siegen to Margarethe Neurath (born 1574), with whom he had at least six children.^{[citation needed]} In 1599 he was appointed president of the Nassau College in its temporary location in Siegen, returning with it to Herborn in 1602.^[1] At the same time he began his political career by serving as a member of the Nassau (Germany) county council.

For the next several years, he was involved in several colleges in the area, variously serving as their president and lecturing on law and philosophy. In 1603 he was elected as a municipal trustee of the city of Emden, in East Frisia, where he ultimately made his fame. He became a city Syndic in 1604, which placed him at the helm of Emden's governance until his death.

In 1617, Althusius published his principal judicial work, Dicaeologicae. In this work, he categorized laws into two main types: natural laws and positive laws, and argued that natural law is "the will of God for men."^[3] Althusius contended that terms such as "common law" and "moral law" were other names for natural law. In order to know the true dictates of natural law, he argued, we must carefully study Scripture and tradition, as well as revelation and reason.^[4]

Johannes Althusius died on August 12, 1638, in Emden.^[1]

Althusius saw confederations as feasible and successful cooperative constitutional orders. In his view, a confederation could be built on successive levels of political community where each community pursues common interests. A village was a union of families, a town was a union of guilds, a province was a union of towns, a state was a union of provinces, and an empire was a union of states.^[12] Althusius' understanding of society as a community of communities informed his views on the nature of politics and federalism (consociatio symbiotica). For Althusius the purpose of politics was the "science of those matters which pertain to the living together" and federations perfectly put the purpose of politics into practice. Althusius's federalism did not involve the surrendering of power, instead it rested on responsibly sharing power.^[13]

Althusius became one of the principal European thinkers on federalism at the start of the 17th century while the European continent was ravaged by religious wars. Against the backdrop of the Reformation and the rise of absolutist monarchies, Althusius identified the German Holy Roman Empire as a commonwealth were the majority could decide matters for all.^[14] In reference to Aristotle, Althusius examined the confederate institutions of the Holy Roman Empire and established a theory of federalism where power is shared among autonomous smaller and larger political communities.^[15] Althusius was Calvinist and did not hold Thomas Aquinas's theory on the commonwealth in high regard. In 1603 Althusius published Politica Methodice Digesta, setting out his theory on building a federal political system out of political associations that were grounded in the free initiative of citizens.^[16]

Althusius relied on the neo-Platonian idea of a universal brotherhood, thus he combined the Greco-Roman ideal of an association that was governed by reciprocal relationships with the Catholic Christian principled of subsidiarity.^[17] Althusius' teachings presented an alternative to the theories of his contemporary Jean Bodin on sovereignty. According to Althusus, natural law gave citizens the right to resist tyrannical government and sovereignty rested with the community, not the ruler. Therefore Althusius maintained that legitimate political authority was founded on smaller communities.^[18]

• Civilis conversationis libri duo, 1601
• Politica, the first edition of which was completed in 1603, is considered not only the most fully developed scheme of Calvinist political theory, but also the only systematic justification of the Dutch Revolt. Althusius took from thinkers in various fields, including Aristotle, Calvin, Bodin, Machiavelli, Grotius, and Peter Ramus; Politica cited close to 200 books in all; the first edition of Politica was received with wide acclaim in Emden and in the Netherlands beyond. It may have been influential on American via Alexander Henderson.
• Dicaeologica libri tres, totum et universum Jus, Frankfurt, 1618. Sections of this work have been recently translated into English and published by Christian's Library Press as On Law and Power (2013).

• Althusius, Johannes (1997) [1603], Politica, Edited and translated by Frederick Smith Carney, Liberty Fund, ISBN 9780865971158.
• Althusius, Johannes (2009) [1603], Malandrino, Corrado (ed.), La politica (in Latin and Italian), translated by Corrado Malandrino; Francesco Ingravalle; Mauro Povero, Turin: Claudiana.
• Althusius, Johannes (2013) [1617], On Law and Power. CLP Academic.