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C H A P T E R  10

 P H I L O S O P H Y

11th & 12th Centuries







A problem or question is advanced.

Arguments for and against this position are explored.

A conclusion is reached.

Is it in or outside this world?

Is it in or outside the mind?

Is it matter or mind?




What makes it the case that a group of things are similar?

To what do universal terms refer?
Does dog refer to a collection of similar things? (Nominalism)
Is it an essence or form? (Realism)

Where do they exist? Are they in particular?

If they are fictitious, how does affect knowledge?





Should reason lead faith?

Should faith lead reason?

         Anselm said:


I do not try, Lord, to attain Your lofty heights because my understanding is in no way equal to it. But I do desire to understand your truth a little, that truth that my heart believes and loves. For I do not seek to understand so that I may believe, but I believe so that I may understand. For I believe this also, that ‘unless I believe, I shall not understand.






What are the foundations of moral values?

Does God will something because it is right? (Intellectualism)

       This position limits God's power.

Is something right because God wills it? (Voluntarism)

           Euthyphro by Plato:


EUTHYPHRO: Yes, I should say that what all the gods love is pious and holy, and the opposite which they all hate, impious. ...

SOCRATES: ... The point which I should first wish to understand is whether the pious or holy is beloved by the gods because it is holy, or holy because it is
beloved of the gods.




Saint Anselm of Canterbury (1033–1109) 76 years

Archbishop of Canterbury







Author: Saint Anselm of Cantebury (1033-1109)

Type of work: Theology

First transcribed: Monologion 1076, Prosologion 1077-1078



The Ontological Argument:


"The fool hath said in his heart, there is no God," Psalm 14. To deny the existence of God requires that you understand the concept. Since God is the Being than whom no greater can be conceived, and since it is better to exist in fact than merely in the imagination, God must exist in fact.


The Weak Argument:

1.  God is that than which no greater can be thought to be (TB)

2.  TB exists in intellectu & in re

3.  God exists in intellectu & in re


In other words:

1.   I have an idea of God within my understanding.

2.   God is a being that which no greater can be conceived.

3.   It is greater to exists in reality than in thought alone.

4.   If God, the greatest conceivable being, exists in the understanding alone, a greater being can be conceived - one that  also exists in reality.

5.   To conceive of a greater being than the greatest conceivable being is a contradiction.

6.   The greatest conceivable being must exist in reality as well as the understanding.

7.   Therefore God exists in reality.



In Behalf of the Fool
The monk Gaunilo argued against Anselm In Behalf of the Fool.  Gaunilo claimed that Anselm's argument fails because it depends on our having an idea of God. We cannot have any idea of God because God's nature is wholly inconceivable. 


Anselm responds by saying that the proof does not require a complete understanding of God.  It only requires that we understand that God is such that no greater can be conceived. 


Gaunilo's second objection is that the argument leads to absurd conclusions. For example  I have an idea of an island of which no greater island can be thought to be. If it exists in the mind alone, it would not be the greatest conceivable island; therefore it must exist in reality. We call this type of an argument a reductio ad absurdum. It attempts to show that a position results in an absurdity.

Anselm's responded by saying that God is the greatest conceivable thing. This concept refers to one thing only. Existence is contained in the essence of only one thing, and it's not an island. It is not a contradiction to talk about possible islands, or any other contingent thing, that does not exist. It is a contradiction to talk about necessarily existing things that don't exist.


Gaunilo's most devastating argument is that existence is not a predicate (property). If we considered existence to be a property of things, all of predicate logic would collapse. Unfortunately Anselm hardly seems to be aware of it.  As if the objection had not been stated, he simply repeats himself; he says that if we understand a thing, than it is in the understanding. He should have responded with this second argument.


The strong argument is as follows:


1.  God is that than which no greater can be thought to be (TB)

2.  TB exists in intellectu & necessarily in re

3.  God exists in intellectu & necessarily in re


Necessary existence is a predicate if such a thing exists. Logic of possible, contingent (actual), and necessary existence is called modal logic.




Peter Abelard (1079– 1142) 63 years

French scholastic philosopher, theologian and logician.



He was castrated for his love affair with Heloise.

is book On the Devine Unity and the Trinity was condemned.

He was prosecuted for heresy.






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