Plato states that there are two conceptions of science, one that one may call noumenic and the other that we may call phenomenic. According to the first, the physical order is the manifestation of an ordering mind, a nous , he sums it up in these words (X 903 C): The ruler of the universe has ordered all things with a view to the excellence and preservation of the whole.
The opposite view, which was represented by Democritus theory of atoms and celestial bodies in collision, is summed up by Plato in these terms (X 889 B):
They say that fire and water, and earth and air, all exist by nature and chance, and none of them by art, and that as to the bodies that come next in order — Earth, and Sun, and Moon, and stars—they have been created by means of these absolutely inanimate entities . . . After this fashion and this manner the whole heaven has been created, and all that is in heaven, as well as all animals and plants, and all the changes of seasons, having had their origin not by mind, not from any god or art, but, as I was saying, by nature and chance.
For upholding this second view of science, Giordano Bruno was imprisoned for seven years and, when it was seen that in spite of the repeated tortures he would not agree even to a partial recantation was finally put to death. It must be kept in mind that in the famous passage1 in which Bruno sums up his cosmology with the motto veritas temporis filia (a motto that was later adopted by Galileo), he oassage of Aristotles Meteorologica in which Aristotle tries to refute the contention that a planet may become a comet or a comet may become planet — and takes his stand with the opponents of Aristotle. In the work entitled Spaccio della bestia trionfante (which means The Expulsion of the Triumphant Beast, that is, Aristotelian cosmology) Bruno propounds an interpretation of ancient astromythology that is similar to that followed by Velikovsky.2
Galileo expressed with superb lucidity of thought and expression the epistemological conflict between his spokesman and his Aristotelian opponent:
Salviatus: But to give Simplicius yet fuller satisfaction, and to reclaim him, if possible, from his errors, I affirm that we have in our new age new occurrences and observations and such that I doubt not in the least that, if Aristotle were here today, they would make him change his opinion. This may be easily gathered from the very way he argues, for when he writes that he esteems the heavens unalterable because no new thing was seen to be born there, or any old one to be dissolved, he seems to imply that, if he were to see any such accident, he would then hold the contrary and put observation before natural reason (as indeed is right); for, had he not made any reckoning of the senses, he would not then have argued immutability from not seeing any change. Simplicius: Aristotle deduced his pricipal argument a priori, showing the necessery of the unalterability of heaven by natural, manifest, and clear principles, and then established it a posteriori by sense and the traditions of the ancients.
The astronomical question, whether the solar system is unalterable, cannot be settled a priori, but must be settled a posteriori, by examining the traditions of the ancients. Galileo stated that astronomical ineories about the structure of the solar system must stand or fall on the historical record. Even Newton, although he did not liked what he found in the historical record, granted as much. One cannot defend Newtons cosmology without detending also the conclusions of his historical studies.
Indeed, any phenomenic science, any science which is not based on noumenic premises dogmatically accepted, is bound to be to some extent tentative and even controversial. It cannot be the object of total and precise knowledge, but only of a partial and conjectural one. It is the recognition of this necessarily partial and relative character of our knowledge, of the impossibility of the building of a univocal and objective representation of the universe, that constitutes—in one of its aspects — the docta ignorantia, the learned ignorance advocated by Nicolas of Cusa as a means of transcending the limitations of our rational thought. If one reads the record of the trial of Galileo, one sees that this was the main argument against him. This appears to be the reason why he chose to sign a recantation; he granted that to those who were asking for absolute certainty his science was of no avail.
History is an empirical science and as such it cannot produce apodic-tic certainty. Yet, properly used, historical science achieves the same results as any other science. The only limit that is specific to this discipline is that it depends on the records of the past that happen to be preserved and it cannot manufacture them if by chance they have been destroyed. Hence, the problem is the factual one of assessing how many and which kind of documents are available. It can be shown on the basis of these documents that history can produce a body of information that is specific and positively significant, even in the area of celestial phenomena.