Two - fold logicians of the 7th century, with reference to the difference in the syntax of generic and indefinite propositions, set out to treat it as one kind of predicative proposition and to change the tripartite division into the quadripartite one. They started criticising the two outlooks of generic indefinite and individual propositions. There is a difference between generic propositions and indefinite propositions. Since the former is not reducible to the confirmation of the subject and predicate, its predicate is not included in its subject, and its real subject is not identical with the mentioned subject. There is no syntactical difference between the generic and individual propositions on the abovc - mintioned issues. Their differences pertain to the predicate. With regard to generic propositions, as distinguished from individual ones, the logicians of the 7th century realized the logical importance of second order concepts. The present article is an attempt to study the contribution of two - fold logicians of the 7th century to the development of logic.
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