Thomas Aquinas never functioned as what we would take to be a philosopher. As a teacher and writer, he focused on trying to pass on what he took to be divine revelation as found in the Bible and as interpreted by the Roman Catholic Church. He took himself to be a theologian. Like many medieval theologians, he was seriously interested in philosophical questions. He raises them in many of his writings. He even wrote commentaries on philosophers such as Aristotle. But, throughout his career as a Dominican friar, he clearly thought of himself as someone whose main job was to pass on and comment on divine revelation. This is evident from his 1256 inaugural lecture as Master of Theology at the University of Paris, in which he reflects on how people like himself should be thinking and acting in accordance with biblical teaching.

Yet Aquinas is now often taken to be the person to study if one is interested in medieval philosophy. It seems to be frequently assumed that Aquinas is the voice of medieval philosophy. This fact seems evident from the enormous amount of attention devoted to Aquinas in books and articles on medieval philosophy published for some years now. In word count this far exceeds what has been written about medieval philosophers other than Aquinas (just as translations of Aquinas's writings into English seem to outnumber translations into English of many other medieval philosophers). Oxford University Press is currently producing a series of ‘Oxford Handbooks’. As of today, only two of them are concerned with medieval philosophy. One of them is entirely devoted to Aquinas. The other is called The Oxford Handbook of Medieval Philosophy. That this should be so indicates the extent to which Aquinas is currently thought of as representing what medieval philosophy was all about. It illustrates the current pervasiveness of what John Marenbon (a distinguished Cambridge historian of medieval philosophy, and a distinguished philosopher in his own right) refers to as ‘Aquinocentrism’.

Yet there were a huge number of medieval philosophers. Even if we think of medieval philosophy as only a Western European thing, it can be thought of as flourishing from around the fifth to the sixteenth century. Its practitioners included Christians, Jews, Arabic authors, and ‘pagans’ (as Aquinas would have called them). Aquinas is just one among very many figures (writing in different languages) who can be cited as medieval philosophers. So, why is it that he is now commonly thought of as the most significant medieval philosopher, the one to focus on when turning to the history of medieval philosophy? What accounts for the fact that the amount of recent secondary literature on Aquinas's philosophy these days far exceeds that devoted to the philosophy of almost all other medieval philosophers put together? Why is it that Aquinas is currently given an historically exaggerated role when it comes to understanding what medieval philosophy actually was?

Part of the answer to these questions lies in Pope Leo XIII's encyclical Aeterni Patris (1879), which, without going into any serious details concerning it, strongly recommended the philosophy of Aquinas as a model for what Christians who are philosophers should be thinking. This encyclical greatly succeeded in promoting the importance of Aquinas among Roman Catholic teachers of philosophy. Its effect can be seen in the fact that many Roman Catholics, and many non-Christians, just assume that medieval philosophy is the philosophy of Aquinas. Its effect can also be seen in Pope John Paul II's 1998 encyclical Fides et Ratio (‘Faith and Reason’). In this text, which is strong on rhetoric but lacking in philosophical analysis, John Paul II made use of a number of different thinkers (including some medieval ones). But only Aquinas is explicitly singled out for his ‘enduring originality’.

Yet Aeterni Patris and Fides et Ratio do not by themselves explain the excessive preeminence that Aquinas currently has in the minds of many people writing about or even casually referring to medieval philosophy. One also has to reckon with ignorance when it comes to the large number of authors who can be listed as medieval philosophers —ignorance which extends to the variety of questions they raised and the answers they provided. It is often assumed that medieval philosophy is simply what Leo XIII called ‘scholastic’ teaching (basically, Latin philosophy coming from the thirteenth and fourteenth centuries). But medieval philosophy is not just that. It includes a load of material coming down to us from Greek Christian authors in the Eastern Roman empire (Byzantium), from Arabic thinkers, and from Jewish thinkers. We might also note that even ‘scholastic’ philosophers often seriously disagreed with each other on philosophical matters. In Aeterni Patris Leo XIII cites Aquinas and St. Bonaventure (who were contemporaries) as paradigm ‘scholastic’ thinkers while seeming to imply that they were both singing the same song. But they disagreed with each other philosophically in some fundamental ways. For example, Summa Theologiae 1a,2 reads like a sustained and philosophical critique of theses defended by Bonaventure concerning our knowledge of God. I might add that Bonaventure and Aquinas were succeeded by other ‘scholastics’ who argued for a variety of philosophical conclusions which are at odds with what we find Aquinas and Bonaventure respectively maintaining. The notion of there being some one thing to be labeled ‘scholastic philosophy’ is very much lacking in historical discrimination. It also ignores the philosophy of medieval thinkers who did not teach in medieval ‘schools’ (i.e., universities such as Paris and Oxford). Many medieval philosophers taught in such places. But many did not. Arabic and Jewish philosophers did not work in the same context as the ‘schoolmen’. Neither did a lot of European medieval philosophers who did their philosophizing in non-university contexts (such as monasteries and courts) or while using literary genres that the ‘schoolmen’ never employed (such as dialogues, encyclopedias, novels, allegories, and even works on medicine and law).

Another thing accounting for Aquinocentrism is academic laziness. Philosophers who do not seriously study the history of medieval philosophy often presume that ‘Aquinas’ and ‘medieval philosophy’ can be treated as synonyms since that is the impression they (understandably) get from the prominence given to Aquinas in much contemporary literature on medieval philosophy (not to mention what their Catholic colleagues or friends might say about Aquinas along the lines of Aeterni Patris and Fides et Ratio). But such philosophers should realize that if they want to get a good sense of what medieval philosophers were about, they need to do a lot more historical work than they seem to be doing. They may reply by saying ‘We don't have time for that’. And maybe they do not. But if that is their final answer when it comes to the suggestion that ‘Aquinas’ and ‘medieval philosophy’ are not synonymous, they are guilty of academic laziness. They should do some research. And so should their students.

Aquinas was a great philosopher. But he is not the voice of medieval philosophy, and we will not properly understand his contribution to the history of philosophy if we cannot see what it amounted to in its full historical context. And a lot of work still needs to be done to explain what that was.