Student: I NOW PERCEIVE that assertions that seem prima facie to be false should not be completely despised. For at first I thought that the assertion for which you strongly argued was completely irrational, yet now it does not seem to me to lack all plausibility. Tell me, therefore, how its defenders reply to the argument against it which I touched on.
Master: They strongly disdain that argument, saying that it is advanced by people who do not know the nature, origin and order of the sciences [See J.A. Weisheipl, =C170 336Classification of the Sciences in Medieval Thought=C186 337, Mediaeval Studies, 27 (1965), pp. 54-90.]. For they say that just as someone judges best mechanical and other [works] which nevertheless he does not know how to make, as for instance many men who do not know how to paint, write, or construct arms, ships and other works made by artisans are known to judge them better than the artisans themselves, so the superior sciences, treating of the causes and principles of matters considered in inferior sciences, can judge those matters more surely and clearly, if they are put to them, than the inferior sciences themselves. Thus also those who have perfect knowledge of a subalternating science, which understands the principles of a subalternated science, judge more certainly about the conclusions, and even the principles, of that subalternate science than do those who have knowledge only of the subalternate science. Thus theologians and true philosophers will be able to judge more profoundly and surely, although often with greater effort, about propositions which are treated in canon law.
Student: I see that my argument is conclusive only for a science which is not subalternate or inferior to another. For I clearly see that it does not seem to have plausibility about a science for which another, superior science lays down rules (as with bridle-making in respect of horsemanship, and about [sciences] subordinate to an architectonic [science], mentioned in the books of Ethics and Politics ), and about a science whose principles are transmitted in a superior science. [Cf. Aristotle, Nicomachean Ethics, I.1, 1094 a10 and Politics, III.11, 1282 a5-6, 17-24; see also Posterior Analytics, I.13, 78 b35-79 a13 and Physics II.2, 194 a7-12, 33-194 b8. According to Aristotle the user (e.g. the educated person) judges the work of the artisan, the horseman judges the work of the bridle maker: in practical matters the end provides the criterion of the means. Of speculative sciences, some are subalternate to others (e.g. astronomy, optics, harmonics and mechanics are subalternated to geometry. For Ockham's views on subalternation see Summa logicae, III.ii.21 (G. Gál and S. Brown, eds. Opera Philosophica, 1 (St Bonaventure, 1974), pp. 539-42 and J. Livesey, "William of Ockham, Subalternate Sciences and Aristotle's theory of metabasis", British Journal for the History of Science, 18 (1985), pp. 127-45.] And therefore in connection with theology and the science of the canonists [my argument] is known to lack colour, because the science of the canonists receives its principles from theology, as Innocent III attests in Extra, De accusationibus, c. Qualiter and quando [col.745], where he clearly asserts that canonical ordinances sprang at a later date from the texts of the New and Old Testaments. Therefore although I could ask many [questions] about these matters, yet because canonists, being ignorant of the terms of other sciences, would not understand them, I want you in this work to avoid as much as you can terms which are proper to sciences other than theology and the science of the canonists so that canonists may understand everything. Let what has been said about this matter suffice, therefore. I am not solicitous for you to reply to the arguments for the first opinion because they now seem to me very weak and it is clear enough from the above how a reply can be made to them.
Master: I consider that if you were to investigate the above material quite carefully you could easily be favourably disposed to many assertions which you once regarded as completely false . So if anything concerning the above matters still vexes your mind, put it forward if you wish to.
WILLIAM OF OCKHAM, DIALOGUS
part 1, prologue and book 1
Text and translation by John Kilcullen and John Scott
as at december, 2003