that there is no such thing as φαντασία καταληπτικὴ in the Stoic sense of the term, in other words, that no perception contains in itself characteristics, by virtue of which its truth may be inferred with certainty. [1462] This fact being granted, the possibility is in his opinion precluded of there residing in the understanding a standard for the distinction of truth from falsehood. The understanding—and this belief was shared by his opponents—must derive its material from the senses. [1463] Logic tests the formal accuracy of combinations of thought, but gives no insight into their import. [1464] Direct proofs of the uncertainty of intellectual convictions are not therefore needed. The same result may also be attained in a more personal way, by raising the question, how individuals obtain their knowledge. He can only be said to know a thing who has formed an opinion respecting it. In the mean time, until he has decided in favour of some definite opinion, he has still no knowledge. And what dependence can be placed on the judgment of one who has no knowledge? [1465] [(b) Attack on the scientific knowledge of the time.] [(α) The physical views of the Stoics attacked.] In these formal enquiries into the possibility of knowledge, Carneades had chiefly to deal with the Stoics, with whom he holds a common ground in his appeal to the senses. The Stoics were also his chief opponents in his polemic against the material results of the dogmatic philosophy. Natural science having throughout the period of the post-Aristotelian philosophy been subordinated to ethics, ethics likewise engaged more attention at the hands of Carneades than science. [1466] In as far as he studied Natural science, he appears to have been entirely opposed to the Stoic treatment of the subject, and to this circumstance we owe it, that better information is forthcoming regarding his scientific, or rather his theological, investigations than regarding his moral views. The Stoic theories of God and of final causes [1467] afforded ample scope for the exercise of his ingenuity, and from the ground he occupied it was not difficult for him to expose the weak points of that theory. The Stoics had appealed in support of the belief in God to the consensus gentium. How close at hand was the answer, [1468] that the universality of this belief was neither proved to exist, nor as a matter of fact did it exist, but that in no case could the opinion of an ignorant multitude decide anything. The Stoics thought to find a proof of divine providence in the manner in which portents and prophecies come true. To expose this delusion, no very expanded criticism of divination was necessary. [1469] Going beyond this, Carneades proceeded to call in question the cardinal point of the Stoic system—the belief in God, the doctrine of the soul and reason of the universe, and of the presence of design in its arrangements. How, he asks, is the presence of design manifested? Whence all the things which