Dutch-Jewish philosopher, the foremost exponent of 17th-century Rationalism.

Spinoza's grandfather and father were Portuguese and had been crypto-Jews after the Spanish Inquisition had compelled them to embrace Christianity. Later, after Holland's successful revolt against Spain and the granting of religious freedom, they found refuge in Amsterdam. His mother, who also came from Portugal, died when Benedict was barely six years old. The Spinozas were prosperous merchants and respected members of the Jewish community, and it may be assumed that Spinoza attended the school for Jewish boys founded in Amsterdam in about 1638. Outside school hours the boys had private lessons in secular subjects. Spinoza was taught Latin by a German scholar, who may also have taught him German; and he knew to some extent all of the other significant continental languages. In March 1654 Benedict's father died. There was some litigation over the estate, with Benedict's only surviving stepsister claiming it all. Benedict won the lawsuit but allowed her to retain nearly everything.

His studies so far had been mainly Jewish, but he was an independent thinker and had found more than enough in his Jewish studies to wean him from orthodox doctrines and interpretations of Scripture; moreover, the tendency to revolt against tradition and authority was much in the air in the 17th century. But the Jewish religious leaders in Amsterdam were fearful that heresies (which were no less anti-Christian than anti-Jewish) might give offense in a country that did not yet regard the Jews as citizens. Spinoza soon incurred the disapproval of the synagogue authorities. In conversations with other students, he had held that there is nothing in the Bible to support the views that God had no body, that angels really exist, or that the soul is immortal; and he had also expressed his belief that the author of the Pentateuch (the first five books of the Bible) was no wiser in physics or even in theology than were they, the students. The Jewish authorities, after trying vainly to silence Spinoza with bribes and threats, excommunicated him in July 1656, and he was banished from Amsterdam for a short period by the civil authorities. There is no evidence that he had really wanted to break away from the Jewish community, and indeed the scanty knowledge available would suggest the opposite. On Dec. 5, 1655, for example, he had attended the synagogue and made an offering that, in view of his poverty, must have been a rare event for him, and, about the time of his excommunication, he had addressed a defense of his views to the synagogue.

Among Spinoza's Christian acquaintances was Franciscus van den Enden, who was a former Jesuit, an ardent classical scholar, and something of a poet and dramatist and who had opened a school in Amsterdam. For a time, Spinoza stayed with him, helping with the teaching of the schoolchildren and receiving aid in his own further education. In this way he improved his knowledge of Latin, learned some Greek, and was introduced to Neoscholastic philosophy. It may have also been through van den Enden's school that Spinoza became acquainted with the “new philosophy” of René Descartes (Descartes, René), later acknowledged to be the father of modern philosophy. Spinoza's other Christian acquaintances were mostly of the Collegiants, a brotherhood that later merged with the Mennonites; they were especially interested in Cartesianism, the dualistic philosophy of Descartes and his followers.

At the same time, he was becoming expert at making lenses, supporting himself partly by grinding and polishing lenses for spectacles, telescopes, and microscopes; he also did tutoring. A kind of reading and discussion circle for the study of religious and philosophical problems came into being under the guidance of Spinoza. In order to collect his thoughts, however, and reduce them to a system, he withdrew in 1660 to Rijnsburg, a quiet village on the Rhine, near Leiden. Rijnsburg was the headquarters of the Collegiants, and Spinoza's lodgings there were with a surgeon named Hermann Homan. In Homan's cottage Spinoza wrote Korte Verhandeling van God, de Mensch en deszelfs Welstand (written c. 1662; Spinoza's Short Treatise on God, Man, and His Well-Being, 1910) and Tractatus de Intellectus Emendatione (“Treatise on the Correction of the Understanding”), both of which were ready by April 1662. He also completed the greater part of his geometrical version of Descartes's Principia Philosophiae and the first book of his Ethica. Spinoza's attitude in these works already showed a departure from Cartesianism. It was also during this stay that he met Heinrich Oldenburg, soon to become one of the two first secretaries of the Royal Society in London.

His version of Descartes's Principia was prepared while Spinoza was giving instruction in the philosophy of Descartes to a private pupil. It was published by his Cartesian friends under the title Renati des Cartes Principiorum Philosophiae Pars I et II, More Geometrico Demonstratae, per Benedictum de Spinoza (1663), with an introduction explaining that Spinoza did not share the views expressed in the book. This was the only book published in Spinoza's lifetime with his name on the title page.

The philosophy of Spinoza may thus be regarded as a development from and a reaction to that of his contemporary Descartes (1596–1650). Though it has been argued that Spinoza was also much influenced by medieval philosophy (especially Jewish), he seems to have been much more conscious of the Cartesian influence, and his most striking doctrines are most easily understood as solutions of Cartesian difficulties. Clearly, he had studied Descartes in detail. He accepted Descartes's physics in general, though he did express some dissatisfaction with it toward the end of his life. As for the Cartesian metaphysics, he found three unsatisfactory features: the transcendence of God, the substantial dualism of mind and body, and the ascription of free will both to God and to human beings. In Spinoza's eyes, those doctrines made the world unintelligible. It was impossible to explain the relation between God and the world or between mind and body or to account for events occasioned by free will.

The publication of Spinoza's version of Descartes's Principia had been intended to prepare the way for that of his own philosophy, for he had both to secure the patronage of influential men and to show the more philosophically minded that his rejection of Cartesianism was not out of ignorance.

Spinoza became dissatisfied with the informal method of exposition that he had adopted in the Korte Verhandeling and the De Intellectus Emendatione and turned instead to the geometrical method in the manner of Euclid's Elements. He assumed without question that it is possible to construct a system of metaphysics that will render it completely intelligible. It is therefore possible, in his view, to present metaphysics deductively—that is, as a series of theorems derived by necessary steps from self-evident premises expressed in terms that are either self-explanatory or defined with unquestionable correctness. His masterpiece, the Ethica, was set out in this manner—Ordine Geometrico Demonstrata, according to the reading of its subtitle. Its first part, “De Deo” (“Concerning God”), was finished and in the hands of his friends early in 1663. Initially the work was intended to have three parts only, but it eventually appeared (in 1677) in five parts. Spinoza's desire for an impersonal presentation was probably his chief motive for adopting the geometrical method, appreciating that the method guarantees true conclusions only if the axioms are true and the definitions correct. Spinoza, like his contemporaries, held that definitions are not arbitrary but that there is a sense in which they may be correct or incorrect.

The question was discussed at length in his unfinished Tractatus de Intellectus Emendatione. A sound definition, he held, should make clear the possibility or the necessity of the existence of the object defined. Because the Ethica begins with the definition of “substance,” the necessary existent, the entire system is vulnerable to anyone disputing that definition, however cogent the subsequent reasoning may be. In fact, as Gottfried Wilhelm Leibniz, a Rationalist philosopher and mathematician, pointed out, though the system is closely knit, its demonstrations do not proceed with mathematical rigour.

Period of the “Ethica.” In June 1663 Spinoza moved to Voorburg, near The Hague, and it appears that by June 1665 he was nearing the completion of the three-part version of the Ethica. During the next few years, however, he was at work on his Tractatus Theologico-Politicus, which was published anonymously at Amsterdam in 1670. This work aroused great interest and was to go through five editions in as many years. It was intended “to show that not only is liberty to philosophize compatible with devout piety and with the peace of the state, but that to take away such liberty is to destroy the public peace and even piety itself.” As this work shows, Spinoza was far ahead of his time in advocating the application of the historical method to the interpretation of the biblical sources. He argued that the inspiration of the prophets of the Old Testament extended only to their moral and practical doctrines and that their factual beliefs were merely those appropriate to their time and are not philosophically significant. Complete freedom of scientific and metaphysical speculation is therefore consistent with all that is important in the Bible. Miracles are explained as natural events misinterpreted and stressed for their moral effect.

In May 1670 Spinoza moved to The Hague, where he remained until his death. He began to compose a Hebrew grammar, Compendium Grammatices Linguae Hebraeae, but did not finish it; instead, he returned to the Ethica, although the prospect of its publication became increasingly remote. There were many denunciations of his Tractatus Theologico-Politicus as an instrument “forged in hell by a renegade Jew and the devil.” When the Ethica was completed in 1675, Spinoza had to abandon the idea of publishing it, though manuscript copies were circulated among his close friends.

Spinoza concentrated his attention on political problems and began his Tractatus Politicus, which he did not live to finish. During the post-Ethica period, he was visited by several important people, among them Ehrenfried Walter von Tschirnhaus (in 1675), a scientist and philosopher, and Gottfried Wilhelm Leibniz (Leibniz, Gottfried Wilhelm) (in 1676), like Spinoza, one of the foremost Rationalists of the time. Leibniz, having heard of Spinoza as an authority on optics, had sent him an optical tract and had then received from Spinoza a copy of the Tractatus Theologico-Politicus, which deeply interested him. According to Leibniz' own account, he “conversed with him often and at great length.” Spinoza, however, was now in an advanced stage of consumption, aggravated by the inhaling of glass dust from the polishing of lenses in his shop. He died in 1677, leaving no heir, and his few possessions were sold by auction. These included about 160 books, the catalog of which has been preserved.

In accordance with Spinoza's previous instructions, several of his friends prepared his manuscripts secretly for the press, and they were sent to a publisher in Amsterdam. The Opera Posthuma (Dutch version: Nagelate Schriften), published before the end of 1677, was composed of the Ethica, Tractatus Politicus, and Tractatus de Intellectus Emendatione, as well as letters and the Hebrew grammar. His Stelkonstige reeckening van den regenboog (“On the Rainbow”) and his Reeckening van kanssen (“On the Calculation of Chances”) were printed together in 1687. The Korte Verhandeling was lost to the world until E. Boehmer's publication of it in 1852.

Spinoza has an assured place in the intellectual history of the Western world, though his direct influence on technical philosophy has not been great. Throughout the 18th century he was almost universally decried as an atheist—or sometimes used as a cover for the detailing of atheist ideas. The tone had been set by Pierre Bayle, a Skeptical philosopher and encyclopaedist, in whose Dictionnaire historique et critique Spinozism was described as “the most monstrous hypothesis imaginable, the most absurd”; and even David Hume, a Scottish Skeptic and historian, felt obliged to speak of the “hideous hypothesis” of Spinoza.

Spinoza was rendered intellectually respectable by the efforts of literary critics, especially of the Germans G.E. Lessing and J.W. von Goethe and the English poet S.T. Coleridge, who admired the man and found austere excitement in his works, in which they saw an intensely religious attitude entirely divorced from dogma. Spinoza has also been much studied by professional philosophers since the beginning of the 19th century. Both absolute Idealists and Marxists have read their own doctrines into his work, and Empiricists, while rejecting his metaphysical approach, have developed certain detailed suggestions from his theory of knowledge and psychology.