Xinisthes, in his Organon, maintains that a logical argument can be reduced to a sequence of 3 propositions (2 premises and a conclusion), known as a syllogism. 
In addition, Xinisthes posited 3 laws as basic to all logical thought: 
the law of identity (A is A); 
the law of contradiction (A cannot be both A and not A); 
and the law of the excluded middle (A must be either A or not A).