Gersonides (Levi ben Gershom)

Works

• 1329The Wars of the Lord (Milhamot Adonai)

  Six books on immortality, prophecy, God’s knowledge, providence, the heavens and creation – where Maimonides held a question undecidable, Gersonides looked for a demonstration.

Position

Gersonides is the most thoroughgoing Aristotelian among medieval Jewish philosophers, and he parts from Maimonides on exactly the questions Maimonides considered beyond demonstration. The Wars of the Lord treats six subjects: the immortality of the soul, prophecy and dreams, God’s knowledge, providence, the heavenly bodies, and creation. Immortality belongs to the “acquired intellect” – the knowledge a person has gained – so that each person survives as what he or she has understood. On God’s knowledge he rejected Maimonides’ view that God knows particulars in a way wholly unlike ours. God knows things insofar as they are ordered, through the laws that govern them, but does not know in advance which of the possibilities open to a free agent will be chosen; otherwise contingency and choice would be illusions. He did not regard this as an imperfection, since what is not yet determined is not there to be known. On creation, where Maimonides had argued that neither eternity nor creation could be proved, Gersonides offered demonstrations that the world had a beginning and argued, with Plato’s Timaeus, that it was made from a formless body rather than from nothing. The fifth book, on astronomy, corrects Ptolemy on the basis of his own observations. Opponents called the work “Wars against the Lord”, and Hasdai Crescas and Isaac Abrabanel criticised him at length.

Life & context

Levi ben Gershom, known in Latin as Gersonides and in Hebrew by the acronym Ralbag, was born in 1288 in Provence, perhaps in Bagnols-sur-Cèze. He spent most of his life in Orange, then outside the French kingdom, and travelled several times to Avignon, the seat of the popes. Little is known of his education. He read Aristotle in Hebrew translations of Averroes’ commentaries and wrote supercommentaries on them in the early 1320s. He also wrote on arithmetic and geometry, commented on the Bible – his commentary on Job (1325) was among the first Hebrew books ever printed – and worked as an astronomer, making his own observations and building a measuring instrument that Christian writers called “Jacob’s staff”. The astronomical part of his main work was translated into Latin in his lifetime, and in 1342 he dedicated a revised Latin version of the chapters on the instrument to Pope Clement VI. The Wars of the Lord was finished in 1329 after some twelve years of work. He died on 20 April 1344.

Further main works

• Supercommentaries on Averroes’ commentaries on Aristotle (c. 1319–24)
• The Work of the Calculator (Maʿaseh hoshev, 1321)
• Commentary on Job (1325)
• Commentaries on the Torah, the Song of Songs and other biblical books