No follower of Carneades and Clitomachus, such as Catulus undoubtedly was[247], could view with indifference the latest development of Academic doctrine. The famous books of Philo were probably not known to Catulus[248]. I now proceed to draw out from the references in the _Lucullus_ the chief features of the speech of Catulus the younger. It was probably introduced by a mention of Philo's books[249]. Some considerable portion of the speech must have been directed against the innovations made by Philo upon the genuine Carneadean doctrine. These the elder Catulus had repudiated with great warmth, even charging Philo with wilful misrepresentation of the older Academics[250]. The most important part of the speech, however, must have consisted of a defence of Carneades and Arcesilas against the dogmatic schools[251]. Catulus evidently concerned himself more with the system of the later than with that of the earlier sceptic. It is also exceedingly probable that he touched only very lightly on the negative Academic arguments, while he developed fully that positive teaching about the πιθανον which was so distinctive of Carneades. All the counter arguments of Lucullus which concern the destructive side of Academic teaching appear to be distinctly aimed at Cicero, who must have represented it in the discourse of the day before[252]. On the other hand, those parts of Lucullus' speech which deal with the constructive part of Academicism[253] seem to be intended for Catulus, to whom the maintenance of the genuine Carneadean distinction between αδηλα and ακαταληπτα would be a peculiarly congenial task. Thus the commendation bestowed by Lucullus on the way in which the _probabile_ had been handled appertains to Catulus. The exposition of the sceptical criticism would naturally be reserved for the most brilliant and incisive orator of the party--Cicero himself. These conjectures have the advantage of establishing an intimate connection between the prooemium, the speech of Catulus, and the succeeding one of Hortensius. In the prooemium the innovations of Philo were mentioned; Catulus then showed that the only object aimed at by them, a satisfactory basis for επιστημη, was already attained by the Carneadean theory of the πιθανον; whereupon Hortensius showed, after the principles of Antiochus, that such a basis was provided by the older philosophy, which both Carneades and Philo had wrongly abandoned. Thus Philo becomes the central point or pivot of the discussion. With this arrangement none of the indications in the _Lucullus_ clash. Even the demand made by Hortensius upon Catulus[254] need only imply such a bare statement on the part of the latter of the negative Arcesilaean doctrines as would clear the ground for the Carneadean πιθανον. One important opinion maintained by Catulus after Carneades, that the wise man would opine[255] (τον σοφον δοξασειν), seems another indication of the generally constructive character of his exposition.