Lecture 2 – Aquinas’ five ways
15 September, 2005

Thomas Aquinas (1225-1274)
•	born to a noble family in what is now Italy
•	began his studies in the church at age 5
•	at 16, decided to join the still new (founded 1216) and controversial Dominican order, whereupon his brothers captured him and dragged him home to try to "deprogram" him.  Their attempts failed; eventually, he was permitted by him family to take his orders in the Dominican order.  The difficulties engendered by his choice of order continued into his studies.  There was a long resistance to granting him his M.A. because of his membership in a mendicant order.
•	a student and disciple of Albertus Magnus (Albert the Great), a leading Aristotelian scholar.  Aquinas remained a committed Aristotelian throughout his career.
•	note thesis, objection, reply format of medieval argumentation

Aquinas's 2 criticisms of the ontological argument
1.	this definition doesn't capture what many of us mean by "God"; 
2.	the argument is missing a premise to the effect that "There exists some x, such that..."  Without such an existential assertion, the properties that we deduce the "x" to have are only the properties of an ideal and not a real entity.  Once you know something exists, you might be able to prove that it has certain qualities, but you cannot prove the existence in reality of an ideal entity by dint of that ideal entity's qualities, even if they are necessary qualities.
 
Two problems about the existence of God:
1.	If there were a principle of infinite goodness, nothing bad could exist.  Bad things exist.  Therefore, there is no such principle.  
2.	Ockham's razor:  Never multiply entities.  We can explain the world without taking recourse to an entity like God.  Therefore, God does not exist.

The Five Ways (Note problem of infinite regress.)
1.	"The first and clearest way derives from facts about change."  Some things change.  Anything that changes must have some potentiality to be what it changes into.  The causes of change must, by contrast, be actual.  Something actually so-and-so draws something that is only potentially so-and-so into being more so-and-so.  (Fire is actually hot, causes wood, which is only potentially hot, into being actually hot too.)  Regress of causes to a first actuality.  
2.	Efficient causation.  Similar argument to above.  (Outline Aristotle's four causes:  material, efficient, formal, final.)
3.	Possibility and necessity.  If something can fail to exist, then it must have some time have failed to exist.  (Is this true?  Why or why not?)  "If everything could fail to exist, there would have been a time at which nothing existed."  So what exists would have arisen out of nothing.  But nothing comes from nothing.  Therefore, there must have been something that exists necessarily.  And, again, there cannot be an infinite regress of necessary beings.  There must be some necessary being that does not owe its existence to anything else.  This is God.
4.	Argument from gradation.  Things have more or less of a quality according to that quality's distance from a maximum.  Therefore, there must be a greatest of all gradations -- a greatest true, good, beautiful, etc.  The greatest thing of a kind is the cause of everything of that kind.  (Question:  does being come in gradations?  Aristotle and Aquinas seem to think so.)
5.	Argument from design.  Things act for a purpose.  They always act in the same way, and they tend toward what is best.  Therefore, some intelligence must have invested them with this purpose.  (The arrow must be directed by the archer.)  This intelligence is God.  

Replies to the "two problems":
1.	God is able to draw goodness out of bad things.  Therefore, the world is better because of the bad things in it.  (If we cannot understand how this is the case, it is only because our intelligence is too limited to fathom God's workings.)
2.	The "five ways" answer the second problem.

Mill’s response to Aquinas:
•	"Who made me?" immediately suggests the question "Who made God?"  If anything (such as God) can exist without a cause, then why shouldn't other things?  The world could have come into existence without a cause.

One of Russell’s responses to Aquinas:
•	The world could have always existed.  "The idea of things must have a beginning is really due to the poverty of our imagination."