Inductive Proof of Astrology (al-burhān al-istiqrāʾī)
Definition
The inductive proof (Arabic al-burhān al-istiqrāʾī, from istiqrāʾ, 'induction') is Abu Ma'shar's signature defense of astrology in Part I of the Great Introduction. He argues by analogy from everyday observational arts that are already accepted as legitimate — farmers knowing planting-times, sailors knowing wind-seasons, stock-breeders knowing mating-seasons, midwives reading the signs of pregnancy, physicians knowing the crisis-days of a fever — to the conclusion that the learned can likewise read the stars' significations from sustained observation. Astrology's method is the same induction, so it deserves the same standing.
In Tradition
Abu Ma'shar and the proponents of the art held that astrology's claims are established the way the other observational arts establish theirs — by induction from accumulated experience — and grounded its causation in Aristotelian natural philosophy, the celestial bodies acting as natural causes of change below. Because its everyday inductive parallels (farming, sailing, breeding, midwifery, medicine) are uncontroversially accepted, astrology's parallel inductive method should be accepted too; its knowledge rests on observation and analogy, not on any claim to occult insight.
In Practice
Use this argument to frame how you reason from a chart and to set the limits of what a chart can claim. Treat each signification as a tested, inductive generalization — a pattern observed to recur, the way a farmer learns planting-times or a physician learns crisis-days — rather than as a fixed decree, and reason by analogy from the accepted natural influences of the celestial bodies to the finer significations of the planets and signs. When you judge, present the reading as observational inference about likely outcomes, grounded in observed correspondence and weighed by converging testimony, not as certain knowledge of the hidden. The same framework licenses refining the received significations against your own continued observation, since the body of doctrine was itself built inductively over generations and rests on analogy to arts no one disputes.
Historical Origin
The inductive proof is set out in Abu Ma'shar al-Balkhi's The Great Introduction to the Science of Astrology, Part I Tractate 2 (§§2.13-2.31), in the critical edition translated by Keiji Yamamoto and Charles Burnett (Brill, 2019). Abu Ma'shar (787–886 CE) grounds the argument in Aristotelian natural philosophy; it became the foundational Arabic-Persian apologetic, inherited by al-Qabisi, Bonatti, and the later Latin defenders of the art.