Galen’s estimate of Dioscorides.
Of all previous writers upon materia medica Galen preferred Dioscorides. He writes, “But Anazarbensis Dioscorides in five books discussed all useful material not only of herbs but of trees and fruits and juices and liquors, treating besides both all metals and the parts of animals.”[677] Yet he does not hesitate to criticize certain statements of Dioscorides, such as the story of mixing goat’s blood with the terra sigillata of Lemnos. Dioscorides had also attributed marvelous virtues to the stone Gagates which he said came from a river of that name in Lycia; Galen’s comment is that he has skirted the entire coast of Lycia in a small boat and found no such stream.[678] He also wonders that Dioscorides described butter as made of the milk of sheep and goats, and correctly states that “this drug” is made from cows’ milk.[679] Galen does not mention its use as a food in his work on medicinal simples, and in his treatise upon food values he alludes to butter rather incidentally in the chapter on milk, stating that it is a fatty substance and easily recognized by tasting it, that it has many of the properties of oil, and in cold countries is sometimes used in baths in place of oil.[680] Galen further criticizes Dioscorides for his unfamiliarity with the Greek language and consequent failure to grasp the significance of many Greek names.
Galen’s dogmatism: logic and experience.
Daremberg said of Galen that he represented at the same time the most exaggerated dogmatism and the most advanced experimental school. There is some justification for the paradox, though the latter part seems to me the truer. But Galen was proud of his training in philosophy and logic and mathematics; he stood fast by many Hippocratic dogmas such as the four qualities theory, he thought[681] that in medicine as in geometry there were a certain number of self-evident maxims upon which reason, conforming to the rules of logic, might build up a scientific structure. In the De methodo medendi[682] he makes a distinction between the discovery of drugs and medicines, simple or compound, by experience and the methodical treatment of disease which he now sets forth and which should proceed logically and independently of mere empiricism, and he wishes that other medical writers would make it clear when they are relying merely on experience and when exclusively upon reason.[683] At the same time he expresses his dislike for mere dogmatizers who shout their ipse dixits like tyrants without the support either of reason or experience.[684] He also grants that the ordinary man, taught by nature alone, often instinctively pursues a better course of action for his health than “the sophists” are able to advise.[685] Indeed, he is of the opinion that some doctors would do well to stick to experience alone and not try to mix in reasoning, since they are not trained in logic, and when they endeavor to divide or analyze a theme, perform like unskilled carvers who fail to find the joints and mutilate the roast.[686] Later on in the same work[687] he again affirms that persons who will not read and profit by the books of medical authorities and whose own reasoning is defective, should limit themselves to experience.
Galen’s account of the Empirics.
Normally, however, Galen upholds both reason and experience as criteria of truth against the opposing schools of Dogmatics and Empirics. The former attacked experience as uncertain and impossible to regulate, slow and unmethodical. The latter replied that experience was consistent, adaptable to art, and proof enough.[688] Galen’s chief objection to the Empirics is that they reject reason as a criterion of truth and wish the medical art to be irrational.[689] “The Empirics say that all things are discovered by experience, but we say that some are found by experience and some by reason.”[690] Galen also objects to Herodotus’s explanation of the medical art as originating in the conversation of patients exposed at crossroads who told one another of their complaints and recoveries and thus evolved a fund of common experience.[691] Galen criticizes such experience as irrational and not yet put into scientific form (οὔπω λογική). Of the Empirics he tells us further that they regard phenomena only and ignore causes and put no trust in reasoning. They hold that there is no system or necessary order in medical discovery or doctrine, and that some remedies have been discovered by dreams, others by chance. They also accepted written accounts of past experiences and thus to a certain extent trusted in tradition. Galen argues that they should test these statements of past authorities by reason.[692] His further contention that, if they test them by experience, they might as well reject all writings and trust only to present experience from the start, is a sophistical quibble unworthy of him. He adds, however, that the Empirics themselves say that past tradition or “history” (ἱστορία) should not be judged by experience, but it is unlikely that he represents their view correctly in this particular. In another passage[693] he says that they distinguish three kinds of experience, chance or accidental, offhand or impromptu, and imitative or the repetition of the same thing. In a third passage[694] he repeats that they held that observation of one or two instances was not enough, but that oft-repeated observation was needed with all conditions the same each time. In yet another place[695] he says that the Empirics observe coincidences in things joined by experience. He himself defines experience as the comprehending and remembering of something seen often and in the same condition,[696] and makes the good point that one cannot observe satisfactorily without use of reason.[697] He also admits in one place that some Empirics are ready to employ reason as well as experience.[698]
How the Empirics might have criticized Galen.
Having noted Galen’s criticism of the Empirics, we may imagine what their attitude would be towards his medicine. They would probably reject all his theories—which we, too, have finally discarded—of four elements and four qualities and the like, and would accept only his specific recommendations for the cure of disease based upon his medical experience; except that they would also be credulous concerning anything which he assured them was based upon his own or another’s experience, whether it truly was or not. They would, however, have probably questioned much of his anatomical inference from the dissection of the lower animals, since he tells us that they “have written whole books against anatomy.”[699] Considering the state of knowledge in their time, their refusal to attempt any large generalizations or to hazard any scientific hypotheses or to build any risky medical system was in a way commendable, but their credulity as to particulars was a weakness.
Galen’s standard of reason and experience.
On the whole Galen’s attitude towards experience seems an improvement upon theirs. He was apparently more critical towards the “experiences” of past writers than the average Empiric, and in his combination of reason and experience he came a little nearer to modern experimental method. Reason alone, he says, discovers some things, experience alone discovers some, but to find others requires use of both experience and reason.[700] In his treatise upon critical days he keeps reiterating that their existence is proved both by reason and experience. These two instruments in judging things given us by nature supplement each other.[701] “Logical methods have force in finding what is sought, but in believing what has been well found there are two criteria for all men, reason and experience.”[702] “What can you do with men who cannot be persuaded either by reason or by practice?”[703] Galen also speaks of discovering a truth by logic and being thereby encouraged to try it in practice and of then verifying it by experience.[704] This, however, is not quite the same thing as saying that the scientist should aim to discover new truth by purposive experiments, or that from a number of experiences reason may infer some general law of nature.