Thomas Aquinas (1225 - 1274) Italian

Thomas Aquinas' philosophy is known as Thomism.  It has unofficially been the doctrine of the Roman Catholic Church for centuries.  The Second Vatican Council (1962 - 1965) made Thomism the "perennial philosophy" of the Catholic Church. 

Aristotle's influence over the scholastics was immense.  In their writings, they spoke of every other previous philosopher by his name (e.g. Plato, Augustine).  But they referred to Aristotle only as "The philosopher.

Aquinas and the other scholastics were largely focused on incorporeal substances; God, angels, and souls.  They applied Aristotle's metaphysics to establish a philosophical explanation of these substances.  

Aquinas conceives of the argument from design as proof of the existence of God using Aristotle's notion of a final cause (teleology).  The Teleological argument thus argues that the universe is being directed towards a telos (an end purpose), and the  apparent intelligent design in the world implies the existence of an intelligent designer, God.  (a 90 minute video on the argument)

Another of Aristotle's concepts that Aquinas used was the concept of essential and accidental properties.  An essential property is something that defines a thing (some property the thing must have) (e.g. "hoarseness" in a horse).  An accidental property may or may not belong to the thing (e.g. "brownness" or "whiteness" in a horse.  

In the process of transubstantiation in the Eucharist, Aquinas maintained that the essential substances of the bread and wine were replaced by the essential substances of Christ's blood and body, but the accidental substances of the bread  and wine remained, therefore Christ's blood and body still tasted like bread and wine.     

The 16th century Protestant reformers (e.g. Luther) would take exception to Aquinas' theory of transubstantiation, and the 17th century philosophers we are studying would not concern themselves with theological concepts like the Eucharist at all.  A few derisively mocked the scholastics, referring to them as "the scholastics and their dictator Aristotle" and claiming they were wasting their time trying to prove "how many angels can dance on the head of a pin."  

But, in some areas, Aquinas' thought remained and influenced later pre-enlightenment philosophers.  The one most important for this course is his work on the development on "natural law."  Next week we'll discuss natural law and see Aquinas' contributions to it.