PETITION. — The "right of p." addressed to the supreme authorities of the State (an appeal to the king, as in the English Bill of Rights, or to the Chambers, as in the constitutions of recent centuries, including the Albertine Statute) has been counted among the liberties, civic rights, or constitutional guarantees.
It has never held very great importance, and its efficacy has diminished with the progressive emergence of other means for expressing the popular will and desires (the press, public meetings, political parties, etc.). Nevertheless, the institution has been preserved even in the most recent charters, including the Italian one, on the grounds that it may prove useful in certain circumstances. It is a right belonging to all citizens (in the past, according to a disputed opinion, also to foreigners), but only "to request legislative measures or to expose common needs" (Art. 50). Thus, a p. may be collective or individual, though never on behalf of private interests, for which recourse must be had to the competent administrative or judicial organs. Its examination is regulated by the internal rules of the Chambers. According to the most recent Senate regulations, for instance, the President refers petitions to standing committees, which are empowered to verify their authenticity preliminarily, report monthly on their content, and the Senate then deliberates on their further course. Petitions relating to bills already presented are examined together with those bills.
PETITIO PRINCIPII. — A sophism (v.) consisting in assuming, explicitly or implicitly, as the basis of proof that which is to be demonstrated, for example: "Everything given in thought is only thought; therefore it is impossible to know a reality external to thought."
Aristotle speaks of the p. of p. in *Anal. pr.*, II, 18 (16): "when someone attempts to demonstrate by means of itself what is not known from itself, then it petitions what was sought from the beginning" (τοῦ ἀλεττὰ τὸ ἐξ ἀρχῆς; cf. St. Thomas, *De fallacis*, cap. 13). Here and in the parallel text (op. cit., I, cap. 22 [23]), "ἀρχή" does not mean "principle" as a premise of the syllogism (v.), but has a temporal sense: "what was proposed from the beginning (for demonstration)": "τὸ προσελκυον" (op. cit., II, cap. 18 [16]).