Matoko,
your points represent, or so it seems to me, the most careful of arguments against Spencer’s project. You do Derb an immense service in back-filling points in his argument that he has overlooked.
Nevertheless, to this observer, it seems that you commit the same error of which you complain in Christian polemic. Namely, appealing to the rich variety of the Islamic tradition while at the same time creating a reductionist straw man of the incomparably rich Christian tradition of enlightened inquiry into science and the humanities. Aquinas cites Ibn Rush’d plentifully, but far more does he cite Scripture, Augustine, The Philosopher, Ps.-Dionysius, Damascene and others in his commentaries of philosphical texts. Further, Aquinas did not depend on the divine Averroes for his reception of Aristotle, that came by way of the School of Toledo, independent of the Commentator’s texts (although the philosophy produced by the School of Toledo, esp. by J. Hispanus was heavily dependent on Averroes). There would have certainly been an Aquinas without Averroes, and beyond doubt a Bonaventure, as well as the entire Oxford school.
Further, Bologna, Reggio, Paris, Oxford, and Montpellier all PRECEDE the arrival of the New Learning of Aristotle (i.e. mediated by Islamic Spain) by at least a full generation (more in the case of the older institutions). The intellectual glories of Islamic Spain are impressive enough without your gilding the lily.
It is silly that some commentators here would discount your arguments based on your faith (thereby perpetuating the Derbyshire-Averroist error of presuming a double truth). Nevertheless, Christianity had not permission, but the command to absorb science (in the broad sense) in order to understand the God of creation whose traces are to be seen in the natural world. Thus Augustine’s (s. IV ex/V) argument about Christians as the new Jews plundering the Egyptians. Although this is evident even earlier in Christian scripture itself, as in Galatians St Paul urges according to the Latin Vulgate, his followers to seek out the “enigmas of the figures” in scripture. Paul himself used the Greek word allegory for this. From the beginning, the gates to interpretation were thrown open.
Also, what by the way was Averroes’s reward for his philosophizing? I seem to remember that it won him exile. He was both genius and heretic, as were also a number of geniuses in the Christian realm. It is however to say that he represented the norm of Islamic society, for the verdict of that society upon him was little different from that of Christendom’s on Eriugena.
More to say, but perhaps PJM should rather give us such a duel to constructively consider the question.
My regards, Marcelino
