Life and literature in the Roman republic

by Tenney Frank

In truth, most of Mill’s categories of inductive methods are implicit in Lucretius, for the Epicureans were in his day busily defending their use of induction against the attacks of Stoics. The logical treatise of Philodemus,[11] which of course Mill did not know, seems to have been written very shortly after Lucretius’ death, and it is not at all improbable that Lucretius had heard the lectures of Philodemus before they were finally given to the public. In those lectures the author dwells much on the validity of carefully chosen analogy, for in the field of the unobservable—in evolutionary cosmology, in atomic theory, and in psychology—metaphor and simile have always been and will always be fruitful tools of science. But Philodemus finally insisted on the necessity of basing all inductions on extremely careful observation, of using only essential similarities and pertinent comparisons, and he implied, even if he did not explicitly state it, that every test of “agreement,” “difference,” and “residue” is necessary. Of course the Epicureans fell into the fallacies of incomplete data, as all science based upon inductive methods must, and as beginners they were obviously impatient of delay and over-optimistic; but the correct forms of the inductive processes were all in daily use and if Bacon and Mill had known the treatise of Philodemus, which so well explains the picturesque arguments of Lucretius, they would have shown more respect for the “wisest of the ancients.”

It is in the service of inductive logic that much of Lucretius’ startling imagery is invented. The poetic quality of the book is in no sense “purple-patch” work; it is not an adjunct like the Corinthian columns pasted on Roman concrete walls for ornamental purposes. The pictures will always be found to derive from unusually accurate observations of nature so that they may serve their purpose as the starting points of the induction, or, when induction was impracticable, as a basis for some significant analogue. They are so indelibly presented that the argument which they carry cannot be forgotten. To realize their vital function in the argument one has but to recall a few instances of them: the race-horse leaping forward at the gong, the birds that start singing with the first ray of morning light, the flock of pasturing sheep that from a distance seem not to stir, the particles of dust flitting in a shaft of sunlight, the sudden glory of the dawn, the sea gulls screaming over the whitecaps, the cow in the pasture distraught when her calf is taken from her, the fishes swimming about in the yielding water, the gnat that is so light that its weight is not felt, the dog barking at dreams or deceived by an imagined scent. The science is no less precise in such passages because of the vivid naturalism of the descriptions. It is indeed adapted to the Roman mode of thought, for the dry unimaged style of Epicurus, all too readily satisfied with dogmatic abstractions, would have made little impression upon the Romans.

One may wonder why it is that, although Lucretius possessed such a clear conception of the processes and tools of inductive logic, so little time was spent in the laboratory experimentation desiderated by Bacon. Our books of logic often assume that man’s processes of thought were recent inventions, as if no one argued deductively till Aristotle, or inductively till Bacon. One might as well assume that no human being used the lens of the eye until some one discovered its existence by dissection. Indeed Nausicaa’s remarks to Ulysses are as well packed with the fruits of penetrating reasoning as the pleas of a Philadelphia lawyer, and the paleolithic savages who made stone axes and fire pistons in the primeval forests employed the same forms of logic as the modern chemist in his laboratory. Lévy-Brühl’s conclusion that the “prelogical man” lived just beyond protohistory is not very convincing to the classicist. What is sometimes called a history of logic is of course not a history of the acquisition of the logical capacity, but a history of the conscious analyses of the processes that have long been in use.

The early Greek writers naturally struck out toward the great engrossing questions of God and the universe. Here analogy and deduction could get quicker results than induction because the problem lay beyond the reach of direct observation. Furthermore, mathematics could then proceed upon a few seemingly universal maxims that had come to be considered self-evident from ages of human experience. Here all progress happened to lie in the deductive forms of thought. However, when advance stopped in this direction, after making the most rapid progress that the history of science can record, and when a priori ratiocination was found to lead no farther, then the atomists began at the bottom again with minute observation and patient induction. They used a laboratory method, though it was not at first necessary to make an artificial laboratory, since nature had provided one near at hand with untold data still unrecorded. What need was there of planting seeds and observing the laws of creation in a garden-box until nature’s vast gardens had been studied? The method was just as sound and for the time being far more fertile. It was at this point that Lucretius came into the field. Scientific experimentation indeed had already begun at points where nature did not seem to give sufficiently precise results—one recalls Aristarchus and Archimedes—but it had not proceeded far; not however from lack of scientific curiosity, or from failure to appreciate the value of experiments, but because quicker results were still to be had by exploiting nature’s abundant store of data.

The appreciation of induction and the employment of the scientific processes by Lucretius must of course not be overstressed. Some of the large gains of formal logic have never been more highly valued than by him. In Epicurus and his predecessors, for instance, the concept of infinity had been arrived at deductively and skilfully employed in order to provide time, space, and material for the evolutionary assumption. Lucretius fully appreciated the value of that concept, realized indeed that the creative process of natural evolution could not for a moment be assumed, for the amazingly intricate Nature which had to be explained, except on the hypothesis of infinity. And infinity was to him not merely a logical necessity, it was a stimulating concept that lifted the imagination of man into the realms of high poetry:[12]

For my mind-of-man

Now seeks the nature of the vast Beyond

There on the other side, the boundless sum

Which lies without the ramparts of the world,

Toward which the spirit longs to peer afar,