From Norman DeWitt's "Epicurus and His Philosophy" Chapter 4: "The Canon, Reason, & Nature"
THE Canon was not an afterthought, as the Stoics asserted,1 but occupied the first place in the triad of Canon, Physics, and Ethics. This arrangement is unalterable, because the Ethics were deduced from the Physics and the truth of both Physics and Ethics was subject to the test of the Canon, which included Sensations, Anticipations, and Feelings.
The task of expounding the Canon would be much simpler were it not for ancient and modern confusions and ambiguities that beset the topic. Epicurus disposed of it in a single roll. The word canon denotes a rule or straightedge but metaphorically includes all the instruments employed by a builder. A perspicuous account of it is presented by Lucretius, who mentions also the square and the plumb line.2 Apart from this passage, however, Lucretius misleads the reader, because he gives exclusive prominence to the Sensations and seems to have lacked a clear understanding of the workings of Anticipations and Feelings as criteria.
These last two criteria, it is manifest, were not discussed in the Big Epitome which Lucretius had before him. In the graded textbooks of Epicurus the topic must have been reserved for advanced students. It is doubtful whether Lucretius was even acquainted with the roll that treated of the Canon. This is unfortunate, because his own one-sided treatment is largely to blame for the classification of Epicurus as an empiricist and for the ascription to him of belief in "the infallibility of sensation."
It is an even worse mistake to have confused the tests of truth with the content of truth, that is, the tools of precision with the stones of the wall. This was the blunder of Pierre Gassendi, who revived the study of Epicurus in the seventeenth century. It was his finding "that there is nothing in the intellect which has not been in the senses." From this position John Locke, in turn, set out as the founder of modern empiricism. Thus a misunderstanding of Epicurus underlies a main trend of modern philosophy. This astonishing fact begets an even greater concern for a correct interpretation, which may cause Locke to appear slightly naive.
The institution of the Canon reflects a contemporary striving for an increase of precision in all the arts, sculpture, architecture, music, and mathematics, but the immediate provocation is to be found in the teachings of Pyrrho the skeptic and of Plato. Pyrrho's rejection of both reason and the sensations as criteria rendered acute the need of establishing a canon of truth. In the judgment of Epicurus Plato also ranked as a skeptic, because he belittled the sensations as undependable and phenomena as deceptive, the only real and eternal existences being the ideas. Thus in his system reason became the only contact between man and reality, and human reason was crippled by the imprisonment of the soul in the body.
Epicurus denied the existence of Platonic ideas on the ground that the only existences were atoms and empty space. Thus to his thinking man stood face to face with physical reality and his sensations constituted the sole contact with this reality. Had he stopped at this point he would have been an empiricist, but he did not. He made room also for a kind of intuition, which is incompatible with empiricism. He postulated that man was equipped in advance by Nature for living in his prospective environment, and not in his physical environment alone but also in his social environment. In addition to the five senses this equipment included innate ideas, such as that of justice, and these ideas, because they existed in advance of experience, were called Anticipations. Moreover, as Epicurus postulated, each experience of the individual, the sensations included, is accompanied by a secondary reaction of pleasure or pain. These pleasures and pains are the Feelings, which also rank as criteria, being Nature's Go and Stop signals.
Thus Nature, having equipped man with a triple contact with his environment, becomes a norm, while the Platonic Reason is eliminated along with the Platonic Ideas. It now remains to explain in more detail the dethronement of Reason and the recognition of Nature as the norm.
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