This is a summary of major thinkers of the high middle ages with an emphasis on Thomas Aquinas.

1. The Medieval Synthesis Scientific Revolutions, 1450-1750

2. THE ROMAN CATHOLIC CHURCH (1050-1200)
Albigensians, a.k.a. Cathars
Waldensians
Francis of Assisi
Gregory VII Urban II (1181-1226)
(r. 1073-1085) (r. 1088-1099) Dominic
(1170-1221)
•College of Cardinals
Pope excommunicates Clement III
•Church asserts authority Henry IV (r. 1187-1091)
over Milan Concordat of Worms
(1076)
(1122) Innocent III
(1059) Henry IV absolved
2nd Lateran (1139) (r. 1198-1216)
(1077)
1st Lateran (1123) 3rd Lateran (1179)
Eastern Schism Dictatus Papae Urban II calls for
(1054) (1075) crusade (1095)
First Crusade Second
Henry IV appoints Crusade Third
(1095-1099)
archbishop of Milan (1095-1099) Crusade
(1072) (1189-1192)
Gregory VII driven
from Rome (1084)
Henry IV
excommunicated again
(1080)
Reconquista

3. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t

4. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t
B. An ideology is a systematic set of ideas and/or beliefs
1. used to explain how the world should be and
2. used to justify actions to make or keep it that way.

5. Ideologies . . . map the political and social worlds for us. We
simply cannot do without them because we cannot act
without making sense of the worlds we inhabit. Making
sense, let it be said, does not always mean making good or
right sense. But ideologies will often contain a lot of common
sense. At any rate, political facts never speak for
themselves. Through our diverse ideologies, we provide
competing interpretations of what the facts might mean.
Every interpretation, each ideology, is one such instance of
imposing a pattern -- some form of structure or organization
-- on how we read (and misread) political facts, events,
occurrences, actions, on how we see images and hear
voices. Ideological maps do not represent an objective,
external reality. The patterns we impose, or adopt from
others, do not have to be sophisticated, but without patter
we remain clueless and uncomprehending, on the receiving
end of ostensibly random bits of information without rhyme
or reason. [Ideology: A Very Short Introduction (Oxford:5
Oxford University Press, 2003), 2-3.

6. We might also add that because ideologies are human
fabrications in an attempt to impose order on the world, they
are also the product of historical change. Thus, they are not
stable or unchanging. To understand them, we have to
examine them in their historical context.
Likewise, there is a difference between an ideology that
guides thought and an ideology that acts as an infallible
dogmatism.
6

7. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t
B. An ideology is a systematic set of ideas and/or beliefs
C. Modern vs. Medieval Ideology

8. Modern Medieval
1. Man OK
2. Life can be beautiful
3. Looks, physical pleasure,
success, security, youth
4. PROGRESS

9. Modern Medieval
1. Man OK 1. Man sinful
2. Life can be beautiful 2. Life miserable
3. Looks, physical pleasure, 3. Looks, physical pleasure,
success, security, youth security, youth don’t last
4. PROGRESS 4. Only true happiness in next
world

10. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t
B. An ideology is a systematic set of ideas and/or beliefs
C. Modern vs. Medieval Ideology
D. Sources of Truth
1. Revelation: OT, NT, Koran
2. Tradition: Prophets, Church Fathers, Church Councils
3. Reason: Classical philosophy
a. Plato + Aristotle = Platistotle
b. Religion faces with problem: “What is the
relationship between revelation (faith) and reason?”

11. Ideas are real and
matter is an
illusion.
1st c. BCE mosaic from Pompeii, 124.545. Museo
Archeologico Nazionale, Napoli

12. Ideas are real and
matter is an
illusion.
What about matter
though, Plato?
1st c. BCE mosaic from Pompeii, 124.545. Museo
Archeologico Nazionale, Napoli

13. Plato Aristotle
What makes a horse a
horse?
There is an ideal world of
forms, and an ideal horse.
But, no material horse can
approach this ideal.

14. Plato Aristotle
What makes a horse a
horse?
To know what the ideal horse
is, we need to study all
horses. From that we can
extract the nature of
“horsiness.”

15. Plato Aristotle
What we are asking is: “What is the nature of Truth,
and how can we understand it?”

16. Plato Aristotle
What we are asking is: “What is the nature of
reality, and how can we understand it?”
Don’t forget about scripture!

17. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t
B. An ideology is a systematic set of ideas and/or beliefs
C. Modern vs. Medieval Ideology
D. Sources of Truth
1. Revelation: OT, NT, Koran
2. Tradition: Prophets, Church Fathers, Church Councils
3. Reason: Classical philosophy
a. Plato + Aristotle = Platistotle
b. Religion faces with problem: “What is the
relationship between revelation (faith) and reason?”

18. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t
B. An ideology is a systematic set of ideas and/or beliefs
C. Modern vs. Medieval Ideology
D. Sources of Truth
E. Can’t we just ignore classical philosophy and rely on
scripture? After all, consider the problems it causes?
1. Ibn Sina, a.k.a. Avicenna (979-1073)
a. Platisotler
b. Early thinker concerned with the nature of reality
c. Realists vs. nominalists

19. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t
B. An ideology is a systematic set of ideas and/or beliefs
Modern vs. Medieval Ideology
C. Sources of Truth
D. Can’t we just ignore classical philosophy and rely on
scripture? After all, consider the problems it causes?
1. Ibn Sina, a.k.a. Avicenna (979-1073)
2. Anselm (d. 1109)
a. Application of reason to matters of faith
b. Ontological Proof of God (1077-8)

20. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t
B. An ideology is a systematic set of ideas and/or beliefs
C. Modern vs. Medieval Ideology
D. Sources of Truth
E. Can’t we just ignore classical philosophy and rely on
scripture? After all, consider the problems it causes?
1. Ibn Sina, a.k.a. Avicenna (979-1073)
2. Anselm (d. 1109)
3. Peter Abelard (1079-1141)
a. Attempt to reconcile faith and reason through
dialectic
b. Sic et Non (e12th century)

21. I. The Problem of Orthodoxy
A. Ideology: ideals that people in a society don’t necessarily
follow, but feel guilty when they don’t
B. An ideology is a systematic set of ideas and/or beliefs
C. Modern vs. Medieval Ideology
D. Sources of Truth
E. Can’t we just ignore classical philosophy and rely on
scripture? After all, consider the problems it causes?
1. Ibn Sina, a.k.a. Avicenna (979-1073)
2. Anselm (d. 1109)
3. Peter Abelard (1079-1141)
4. Bernard of Clairvaux (1090-1153)
a. Attack on Abelard
b. Faith is not an opinion

22. I. The Problem of Orthodoxy
A. Ideology
B. An ideology is a systematic set of ideas and/or beliefs
C. Modern vs. Medieval Ideology
D. Sources of Truth
E. Can’t we just ignore classical philosophy and rely on
scripture? After all, consider the problems it causes?
1. Ibn Sina, a.k.a. Avicenna (979-1073)
2. Anselm (d. 1109)
3. Peter Abelard (1079-1141)
4. Bernard of Clairvaux (1090-1153)
5. What about:
a. What about Greco-Roman tradition?
b. Does scripture explain all natural phenomena?

23. I. The Problem of Orthodoxy
A. Ideology
B. An ideology is a systematic set of ideas and/or beliefs
C. Modern vs. Medieval Ideology
D. Sources of Truth
E. Can’t we just ignore classical philosophy and rely on
scripture? After all, consider the problems it causes?
1. Ibn Sina, a.k.a. Avicenna (979-1073)
2. Anselm (d. 1109)
3. Peter Abelard (1079-1141)
4. Bernard of Clairvaux (1090-1153)
5. What about . . . ?
6. However, philosophy can be used to prop up faith,
especially Plato (ideals, creator) and Aristotle
(purpose, a.k.a. first cause and prime mover)

24. I. The Problem of Orthodoxy
II. Medieval Synthesis: Faith and reason can work together
A. Averroes (1126-1198)
1. Argued for a “double truth”  one could come
to separate truths through reason and through
faith
2. Became very popular in the medieval schools
despite the Church’s desire to suppress its
influence

25. I. The Problem of Orthodoxy
II. Medieval Synthesis: Faith and reason can work together
B. Thomas Aquinas (1225-1270)
1. Reason and revelation are part of a single
truth (natural truth / revealed truth)  “double
means”
2. Agreed with Moses-ben Maimon, a.k.a.
Maimonides (1135-1204) that some things are
beyond reason  therefore, philosophy has
to leave some things to faith
3. Man should use reason, but sin is why men
can’t always succeed
4. Can use philosophy (esp. Aristotle) to clarify
some mysteries of the Church
Benozzo Gozzoli, Triumph of St. Thomas Aquinas (1471),
Musée du Louvre, Paris

26. Book I, Ch. 3, “The Double Means of Asserting Truth about God” in Truth of the Catholic
Faith
“Since not every means of expressing the truth is the same – ‘the expert is to aim for as
much accuracy as the nature of the thing permits,’ as was said by the Philosopher
(Ethics 1.2). Now there is a double means of asserting truths about God, for there are
some truths about God which are beyond the faculty of human reason, such as, that
God is three and one, but there are others which philosophers guided by the light of
natural reason can attain, such as that God exists and that God is one.”

27. Book I, Ch. 1, “The Duty of the Sage” in Truth of the Catholic Faith
“According to common usage, which the Philosopher [Aristotle] believes should be
followed in the naming of things, those who impose order on things and govern them
well are called sage. However, in all that is governed or ordered for a purpose it is
necessary to derive the rules for this governing and order from that purpose. For each
and every thing is best arranged, when it is ordered in accordance with its purpose, and
that purpose is the good. “
“The ultimate purpose of all things is that intended by their first creator or mover, and the
first creator or mover of the universe is the Mind. It must therefore be that the ultimate
purpose of the universe is the Good of Mind; which is Truth, and that wisdom is
concerned above all with studying its purpose.”

28. Final Cause (or Purpose)

29. Final Cause (or Purpose)

30. Final Cause (or Purpose)

31. How do religion and philosophy work together?

32. What is sin?

33. Book III, Ch. 122, “How Simple Fornication is a Sin According to Divine Law and that
Marriage is Natural” in Truth of the Catholic Faith
“Now God cares for everyone in accordance with his own good. Anyone’s good is what
furthers his goal [final cause], whereas evil is what diverts him from it. But as with the
whole, so also with the parts, each and every action of man must serve his purpose.
Semen, although superfluous for the preservation of the individual, is necessary for the
propagation of the species. It is true that other superfluities, such as excretion, urine,
sweat, and the like, are not necessary for anything and good only for emission.
However, this is not the only requirement for semen, but also that it be emitted for
procreation, which is the purpose of intercourse. Procreation is, however, in vain unless
it is followed by nutrition. Therefore the emission of semen should be regulated so that
both procreation and rearing can follow.”

34. Book III, Ch. 122, “How Simple Fornication is a Sin According to Divine Law and that
Marriage is Natural” in Truth of the Catholic Faith
“From which it is clear that all seminal emission in such a way that procreation cannot
result is contrary to man’s good, and if done deliberately must be a sin. I am referring,
however, to the method whereby procreation cannot follow by itself: every seminal
emission, for example without the natural union of male and female. This type of sin is
called unnatural. If, however, procreation cannot follow the emission of semen by
accident, this is neither against nature or a sin, for example, if it happens that a woman
is sterile.”

35. What about matters of belief?

36. The Nature of Reality
Essence
Essence
Accident
Accident

37. What about matters of belief?

38. Transubstantiation
Essence
Essence
Accident
Accident

39. Book IV, Ch. 63, “Solution to the Previous Difficulties and Particularly on the Changing of
Bread into the Body of Christ” in Truth of the Catholic Faith
“. . . It must be understood however that the above mentioned changing of bread into the
body of Christ is a different mode from all changes in nature. For in any natural change,
there remains a substance in which different forms succeed each other, either accidental
ones as when white changes into black, or substantial ones air into fire.
Hence they are termed changes of form. But in the change mentioned above crosses
over into a substance, and the accidents remain. Hence this is termed a change of
substance. In what way these accidental qualities persist and why must be scrutinized
later. Now, however we must consider how a substance is changed into a substance,
something which indeed nature cannot do, for all the operations of nature presuppose
matter, through which substances are individuated. Nature cannot make this finger that
finger. But matter is subject to divine power, by which it is brought into being. Hence by
divine power it can come about that this individual substance is changed into that
preexisting substance.”