History of Philosophy Lecture 12 Thomas Aquinas

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History of PhilosophyLecture 12Thomas Aquinas

• By David Kelsey

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Aquinas

• Saint Thomas Aquinas
• Lived from 1225-1274.
• A monk whose writings have been deemed
  authoritative by the Catholic Church.
• In 1244 became a friar. Later he became a priest
  and in 1323 was made a Saint.
• Heavily influenced by the works of Aristotle.
• In his work Summa Theologica he gave 5 different
  arguments for Gods existence.
• He called these the 5 ways.

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Aquinas on Aristotle

• Aquinas on Aristotle
• Aquinas was greatly influenced by the works of
  Aristotle.
• But Aquinas thinks there is a fundamental mistake
  in Aristotles metaphysics.
• Aquinas thinks Aristotle overlooks the notion of
  existence.
• Aristotle on existence
• Form is what actualizes a potentiality, matter,
  into an actually existing thing.
• And efficient causes are what bring a particular
  substance into being.
• But the world, existing eternally, has no
  efficient cause. Existence is just born in its
  form.

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Aquinas on existence

• So for Aristotle, Form brings existence along
  with it. But for Aquinas, a things existence
  differs from its essence.
• The essence of any substance is both matter and
  form for such an object is different from
  something purely formal
• For something imaginary like a phoenix, its
  essence being form and matter, it lacks
  existence.
• So existence is something added to those
  substances that do in fact exist.
• Likewise for spiritual substances, they are
  composed of pure form and existence.
• It is this new understanding of existence which
  leads Aquinas to rethink Aristotles notion of
  efficient causation and subsequently Gods
  existence as unmoved mover.
• We now turn to Aquinas famous 5 ways

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Theism

• There are 3 general argument patterns for Theism.
• Theism, Atheism Agnosticism
• We have so far seen one of these argument
  patterns the Ontological argument.
• Ontological Arguments
• Argue that by an analysis of the very concept of
  God he must exist.
• Cosmological Arguments
• The form of the argument is roughly this
• There must be a first cause of all things and
  this first cause must be God.
• Teleological Arguments
• Argue for Gods existence via premises about the
  design or goals or purposes of things.

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The 5 ways

• The 5 ways
• The first way about things causing change in
  other things.
• The second way about efficient causation
• The third way about things causing others to
  exist
• The fourth way about things causing others to be
  good or noble.
• The final way about purposes.

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Aquinas 5 ways

• The first 4 ways
• Different versions of the Cosmological argument.
• Each way uses a different sense of the word
  cause.
• In each case Aquinas wants to show that there is
  an uncaused cause
• All Cosmological arguments have a form like this
• 1. There is something that causes everything
  else, I.e. a first cause.
• 2. Only God could be a first cause.
• 3. Thus, there is a God.
• The final way a version of the teleological
  argument.

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The first way

• The form of the first way
• 1) Things change.
• 2) Change is an alteration in which something
  becomes actually what it was only potentially
  until then.
• 3) Everything that changes must be made to change
  by another thing.
• 4) But if one thing causes change in another,
  either the cause is a first cause of change or it
  is caused to change by another (from 3)
• 5) There couldnt be an open causal chain of
  changing changers going back forever into the
  past.
• 6) Thus, there is an unchanging changer, a first
  cause of change. (from 1 5)
• 7) And this first cause is God.

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Aquinas argument for the 3rd premise

• The third premise 3) Everything that changes
  must be changed by another thing.
• A change from potentiality to actuality can only
  be brought about by something that is already
  actual.
• The ball and batter
• Nothing can be both potential and actual in the
  same respect.
• So nothing can change itself.
• Thoughts on this argument? Can you think of
  anything that could change itself?

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Aquinas argument for the 5th premise

• The 5th premise There couldnt be an open causal
  chain of changing changers going back forever
  into the past.
• In this case there is no first cause of change
• Open causal chain an infinite number of things,
  one causing change in the other
• Ball and Batter
• But then there couldnt be any intermediate
  causes either
• Such causes could only cause change if actualized
  themselves by some prior cause.
• Ball and Batter again
• But if there werent any intermediate changers
  there would be no change at all.
• Thoughts on this argument?
• Is it possible that we have intermediate causes
  of change without a first cause?
• Maybe there is another possibility a closed loop
  of intermediate changers

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Evaluating the first way

• The first premise
• says simply that things change.
• Change Aquinas means the kind of change we see
  in the ball when it is hit by the bat.
• The fourth premise
• Assuming that everything that changes must be
  changed by another thing, if one thing causes
  change in another, either the cause is a first
  cause of change or it is caused to change by
  another.
• The fifth premise
• There is an unchanging changer, a first cause of
  change.
• This thing isnt changed by anything else. It
  can cause change though.
• Dominos
• Question why suppose that there is just one
  unchanging changer?
• The conclusion
• This first cause is God
• Question why suppose this first cause is God?

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The Second Way

• The Second way
• 1) efficient causes come in series
• Something cannot be the efficient cause of itself
  for to be so it would have to preexist itself,
  which is not possible.
• And if you take away a cause you take away its
  effect
• 2) Such series of efficient causes could not go
  on to infinity
• If the series were infinite there would be no
  first cause.
• If there were no first cause there would be no
  intermediate causes...
• 3) So there must be a first efficient cause
• 4) this everyone gives the name God

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Evaluating the Second way

• Challenging the Second way
• Some things to notice
• Notice the similarity between the first and
  second ways
• The second way is focused on a specific kind of
  causation, efficient causation.
• An efficient cause causes something to come to be
• Example the hammer, the spark and the explosion
• Evaluating the premises
• Premise 1
• Questions?
• Premise 2
• Questions?
• Premise 3
• Questions?
• The conclusion
• Questions?

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The Third Way

• Two ways in which a thing can exist
• Necessary things cant fail to exist.
• Contingent things come into and go out of
  existence.
• The third way
• 1. Some things must exist of necessity.
• 2. There cant be an open causal chain of
  necessary things each causing the next to be
  necessary.
• 3. Thus, something must be necessary per se.
• 4, And this is God.

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The first premise

• The first premise
• Says that something must be necessary.
• So not everything can be contingent.
• His argument
• 1) consider if everything existed contingently.
• 2) All contingent things must start to exist at
  some time.
• 3) So all contingent things must fail to exist at
  some time. (from 2)
• 4) But then there must have been a time at which
  nothing existed. (from 1 3)
• 5) But if there had been such a time nothing
  would exist now.
• From nothing you get nothing
• 6) But things do exist now.
• 7) Something must exist of necessity. This thing
  caused contingent things to come to be.

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Finishing the 3rd way

• The second premise
• says that there cannot be an open causal chain of
  necessary things each causing the next to be
  necessary.
• His argument
• In this case there is no first cause of change.
• But then there couldnt be any intermediate
  causes and so no change at all
• Question?
• The third premise
• says that something must be necessary per se
• Necessary Per Se
• Something that owes its necessity to nothing
  else
• it can cause the necessity of other things
  though.
• Question?
• The conclusion
• Questions?

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The Fourth Way

• The fourth way
• 1) Some things are good (noble and true).
• 2) Some things are better (or more noble or
  truer) than other things.
• 3) These better (more noble and truer) things
  have more good (are more noble and are truer) in
  accord with their distance from a maximum.
• Comparative judgments
• 4) if something that is maximally true, good and
  noble were not in existence then there would be
  no things possessing truth, goodness and nobility
  to a lesser degree.
• So whatever is maximally good (noble and true) is
  the cause of whatever else that is good
• 5) Thus, something is maximally good and causes
  everything else that is good (from 1 4)
• 6) This maximally good thing we call GOD.

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Finishing the argument

• Something to notice
• Notice the appeal that this argument makes to the
  great chain of being
• The first 3 premises
• The fourth premise
• Question This seems to imply that the maximally
  good thing is the cause of whatever else is good.
• Questions?
• Premise 5
• The conclusion

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The fifth way

• The fifth way
• 1) Everything has a design, acts for a purpose.
• 2) Something can only have a design or act for a
  purpose if it is directed to do so by a designer.
• Ex arrows and archers
• 3) Everything has a designer, which we call God.

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The first premise of the Design Argument

• The first premise
• 1) Everything has a design, acts for a purpose.
• Goal-directed behavior is observed in all natural
  substances
• Their behavior hardly ever varies and is almost
  always turning out well
• Just like we plant and harvest and store food for
  the winter, intention and design is pervasive
  throughout
• Examples...

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Understanding the fifth way

• The fifth way
• is a teleological argument for the existence of
  God.
• Teleological Arguments
• Most are arguments by analogy.
• They usually rest on some analogy between things
  we know to be designed by humans and things we
  know not to be designed by humans, such as the
  universe as a whole.
• The analogy is then made if the first has a
  designer so does the second, which is God.

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Thoughts aboutthe fifth way

• Thoughts about the fifth way?
• Finding a relevant difference
• Anyone see a relevant difference?
• Things vs. universes?
• Could something besides God be the designer of
  the universe?
• Other possible designers
• Gravity?
• Evolution?
• Aquinas reply