Computational Aristotelian logic
Aristotelian logic and the revolution of modern logic
This site is devoted to the formal aspects of traditional Aristotelian logic. The Aristotelian system together with its enhancements has been the predominant logic in Europe during more than 2000 years. It has vanished almost completely due to the rise of modern mathematical logic which began with George Boole about 150 years ago.
The rapid transition from traditional Aristotelian to modern symbolical logic has been a veritable revolutionary process, and like always in such a kind of processes, the revolutionaries did not pay too much attention to doing justice to each and every aspect of the old system.
Thus, Aristotelian logic has received a bad reputation since the middle of the 19th century - it was said to have been an incorrect or, at least, unfinished forerunner of modern logic, and modern logicians were eager to show that some of Aristotle's laws were simply wrong - or, at least required additional hypotheses in order to be apt of being correctly transformed into a small subsystem of predicate logic. Even today most university textbooks again and again repeat this kind of assessment of the Aristotelian logic. But this appraisal is wrong.
The new valuation of Aristotelian logic
Works of LUKASIEWICZ in 1951 and later, independently of each other - CORCORAN and SMILEY in 1972/3 showed that Aristotelian logic is a perfect formal logical system of its own which should not and cannot correctly be formalised within our modern system of predicate logic. Modern predicate logic and traditional Aristotelian logic are two systems which, from a formal standpoint (not from a historical point of view, of course), are independent of each other - which means that Aristotelian logic does not need propositional, class or predicate logic in order to be precisely formulated and to be used in practise.
By the way, Lukasiewicz was right in vehemently denying that Aristotelian logic required class- or predicate logic, thus opposing directly Bertrand Russell. However, he was wrong in regarding propositional logic of the Stoics as the system underlying Aristotle's theory.
Today it has been widely accepted by experts of Aristotelian logic that this logic should be seen as a typical "system of natural deduction". It is also clear that Aristotelian "philosphical" logic was designed for quite different purposes than modern symbolic mathematical logic. Whilst there are many reasons not to give too much credit to modern logic with respect to its alleged "universal potential" of formalising logical phenomena of whatever type and provenience, there is, on the other hand, no sensible basis for adhering to a "revisionist" attitude, promising the end of all problems with modern logic by simply switching back to the Analytica priora.
Objective of this websiteThis website has been designed as a "living proof" for the thesis that Aristotelian logic is a perfect formal system of its own. The site contains an online rule-based program in which the traditional rules of Aristotelian term logic have been implemented, not relying in which form so ever on modern propositional or predicate logic. It gives the opportunity for different levels of occupation with the logic of the Analytica Priora: