Its debt to others.
Astronomy and astrology had together long made up the world’s supreme science; there was no originality in urging their importance, and unfortunately it was astrology rather than astronomy which seemed to Bacon by far the most important and practical part of mathematics. In physics he borrowed his discussion of weights and falling bodies from Jordanus, an earlier writer in the thirteenth century, and his optics from Alhazen and Grosseteste and from treatises which passed then under the names of Ptolemy and Euclid but were perhaps of more recent origin.[2148] Bacon’s graphic expression of the multiplication of species by lines and figures we find earlier in Grosseteste’s De Lineis, Angulis, et Figuris.[2149] It does not seem, therefore, that Bacon made any new suggestions of great importance concerning the application of mathematical method in the sciences, and historians of mathematics have recognized that “he contributed nothing to the pure science,”[2150] of whose very meaning his notion was inadequate.
III. His Experimental Science
Has been given undue prominence.
Let us next inquire what contributions, if any, Bacon made in the direction of modern experimental method. Jebb’s edition of the Opus Maius in 1733 ended with the sixth part on “Experimental Science,” which thus received undue prominence and seemed the climax of the work. Bridges’ edition added the seventh part on “Moral Philosophy,” “a science better than all the preceding,” and the text as now extant, after listing various arguments for the superiority of Christianity to other religions, concludes abruptly with an eight-page devout justification and glorification of the mystery of the Eucharist.
Our preceding chapters have similarly rectified the place of Bacon’s discussion of experimental science in the history of thought. We have already brought out the fact that he was not the first medieval man to advocate experimentation, but that writers before him contain “experiments,” rely on experience rather than mere authority, and mention the existence of other “experimenters” and “experimental books.” We have noted Petrus Hispanus’ discussion of “the experimental method” (via experiment), Albertus Magnus’ experimental school for the study of nature, Robert Grosseteste’s association of experimentation with physics, and William of Auvergne’s association of experiment with natural magic. We have described experiments of Constantinus Africanus, Adelard of Bath, Pedro Alfonso, Bernard Silvester, and many others. We have yet to describe experimental books, many of which antedate Roger Bacon. His discussion will be found to do little more than duplicate and reinforce the picture of the medieval status of experimental method which we have already obtained from other and earlier sources. He is not a lone herald of the experimental method of modern science; he merely reveals and himself represents the merits and the defects of an important movement of his time.
“Experimental science” distinct from other natural sciences.
Bacon’s discussion of “experimental science” and of experimental method are not quite one and the same thing. He treats of “experimental science” in a separate section of the Opus Maius, and seems to regard it as something distinct from his other natural sciences, such as optics, alchemy, astronomy and astrology, rather than as an inductive method through regulated and purposive observation and experience to the discovery of truth, which should underlie and form an essential part of them all. Yet he also approaches the latter conception. But note that, while the sixth part on “Experimental Science” is not the last section of the Opus Maius, it is the last of the natural sciences to be discussed by him there rather than the first. It is not, like modern experimentation, the source but “the goal of all speculation.” It is not so much an inductive method of discovering scientific truth, as it is applied science, the putting the results of the “speculative” natural sciences to the test of practical utility. “Other sciences know how to discover their first principles through experience, but reach their conclusions by arguments made from the principles so discovered. But if they require a specific and final test of their conclusions, then they ought to avail themselves of the aid of this noble science.”[2151] “Natural philosophy narrates and argues but does not experiment. The student of perspective and the astronomer put many things to the test of experience, but not all nor sufficiently. Hence complete experience is reserved for this science.”[2152] It uses the other sciences to achieve definite practical results; as a navigator orders a carpenter to build him a ship or a knight tells a smith to make him a suit of armor, so the experimentator uses his knowledge of geometry to construct a burning-glass or outdoes alchemy at its own specialty of gold-making.[2153] In working out these practical inventions, however, the “experimenter” often happens on new facts and truths of which the speculative sciences have not dreamed, and in this way experimental science “by its own power investigates the secrets of nature.” Thus Bacon begins to see the advisability of a close alliance between “experimental science” and natural science, but it is also clear that they are not yet identified. The artisans of the gilds and the alchemists—Bacon includes a discussion of alchemy in the same sixth section with his “experimental science,” although in a way keeping the two distinct—seem to be engaging in this experimental science more than do the scholars of the books and schools. As William of Auvergne associated experimentation with magic rather than with science, so Bacon seems to regard natural science as largely speculative, and confirms the impression, which we have already derived from many other sources, that magicians were the first to “experiment,” and that “science,” originally speculative, has gradually taken over the experimental method from magic. This impression will be strengthened as we proceed to examine in more detail, first Bacon’s “experimental science” and then what he has to say concerning magic. From now on, however, we shall credit Bacon with all the traces of experimental method that we can find anywhere in his writings, as well as in his separate section on “experimental science” in the Opus Maius and his further allusions to the same subject in the Opus Minus and Opus Tertium.
As a criterion of truth.
Bacon not merely emphasizes the importance of experience in arriving at the truth, but of all sciences regards his “experimental science” as the best criterion of truth. “All sciences except this either merely employ arguments to prove their conclusions, like the purely speculative sciences, or have universal and imperfect experiences”;[2154] while “It alone, in truth, has the means of finding out to perfection what can be done by nature, what by the industry of art, what by fraud”; for it alone can distinguish what is true from what is false in “incantations, conjurations, invocations, deprecations, and sacrifices.”[2155]