The cultural impact of Aristotle’s philosophy of logic begins with Thomas Aquinas (1225–1274), who undertook to couple Christian theology to Aristotelian philosophy. The combination is far from self-evident and Aquinas did it only by twisting the ideas of Aristotle almost beyond recognition.

In his “Summa Theologiae,” Aquinas provides a systematic presentation on how to merge syllogistic logic and Christianity. According to Aquinas reason and faith are both important and should coexist harmoniously.

Aristotle must have turned in his grave upon hearing such a suggestion. Mixing logic and faith was anathema to his way of thinking. Nonetheless, I must acknowledge that Aquinas did as a good job as anyone could in his impossible enterprise.

Thomas Aquinas and Aristotle’s philosophy of logic

Aquinas employed extensively the Aristotelian doctrine of the four causes (material, formal, efficient, and final) in order to prove God’s existence. He regarded God as the ultimate final cause for all events in the world.

“Summa Theologiae” argued with copious details that God’s existence can be demonstrated through a series of syllogisms. I must express my admiration at Aquinas’ talent at fabricating an array of proofs larger than all prior attempts in history.

Aquinas was as enthralled by Aristotle’s logic as he was by the Bible; nonetheless, his disquisitions presenting God as “the prime mover” fail to meet the Aristotelian standard of proof. It doesn’t suffice to state that “there must be a prime mover in the universe” and that “God must surely be the prime mover.”

Christianity and Aristotle’s philosophy of logic

Surprisingly enough, Aquinas drew on Aristotelian ethics to justify Christian virtues, but his arguments are far fetched.

For Aristotle, happiness is the goal of life and virtues are methods for attaining the goal. In contrast, Aquinas says that God alone knows life’s purpose and that it is in our interest to obey God. As you can see, Aquinas’ logic is vaguely similar to Aristotle’s, but cannot withstand close examination.

The greatest contribution of Aquinas was to popularize the works of Aristotle. He made hundreds of thousands interested in learning about Aristotle’s logic. Without intending it, he got them to think for themselves and draw correct conclusions.

John Duns Scotus (1266–1308) was another key popularizer of Aristotle’s works. In contrast to Aquinas, Scotus was against merging theology and religion; he favoured Aristotle’s logic for general use, but when it came to religion, he relied on faith.

Criticism against Aristotle’s philosophy of logic

Ramon Llull (1232–1315), a contemporary of Aquinas, also contributed greatly to popularizing Aristotelian philosophy. He presented his ideas in “Ars Magna.” He placed philosophy on a higher ground than other sciences because it gives us a method for thinking logically and creates a universal language.

As Aristotle’s influence spread, some critics found his logic incomplete. For instance, Girolamo Cardano (1501–1576) said that Aristotelian syllogisms are too simple because they do not contemplate probabilistic thinking.

Cardamo’s criticism is wrong because Aristotle’s syllogisms do allow for probabilistic conclusions. Take for example “dark clouds usually announce rain” and “the sky is covered by dark clouds right now.” Those two premises lead to the probabilistic conclusion “it seems that it is going to rain.”

At the same time, other critics were calling Aristotle’s logic too complicated and looking for easier methods. For example, Petrus Ramus (1515–1572) wrote the books “Dialectics” and “Against Aristotle,” where he proposed simplified syllogisms.

Ramus also questioned the usefulness of the categorization of syllogisms made by Aristotle in his “Posterior Analytics.” In his view, it does not help much to inquire whether a conclusion has been drawn from a categorical or a hypothetical syllogism.

Thanks to the work of those philosophers, Aristotelian logic became part of the curriculum in all civilized countries. Every educated person was taught how to draw correct conclusions.

If you are interested in applying Aristotle’s ideas to solving today’s problems, I recommend you my book “The Philosophy of Builders.”

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