Title: Thomas%20Aquinas
1Thomas Aquinas
1225 1274 (Aquinas notes created by Kevin
Vallier)
- Dominican monk, born to Italian nobility.
- Worked 150 years after Anselm.
- Student of Albert the Great
- Studied and commented upon much of Aristotles
works soon after their translation into Latin in
western Europe - Studied important Islamic philosophers including
Avicenna and Averroes, who themselves were
heavily influenced by Aristotle
2Rejection of the Ontological Argument
Granted that everyone understands that by this
word God is signified something than which
nothing greater can be thought, nevertheless, it
does not therefore follow that he understands
that what the word signifies exists actually, but
only that it exists mentally. Nor can it be
argued that it actually exists, unless it be
admitted that there actually exists something
than which nothing greater can be thought.
(Summa Theologica I.II.I)
3- Anselms argument rests on his definition of god
as that which nothing greater can be conceived. - Aquinas rejects the a priori Ontological
argument on the grounds that a words meaning
cannot alone establish the existence of that to
which the word refers. - Rather, Aquinas requires existence proofs be
empirical/ a posteriori, ie. to require
observational evidence.
4Cosmological Proofs for the Existence of God
- Cosmology the empirical study of the universe
considered as a whole system - Eg, Hubbles (1929) discovery that the universe
is expanding rather than in a steady or static
state - Eg, Einsteins (1915) identification of gravity
the curvature of space/time - Eg, The big bang theory of the origin of the
universe
5Cosmological Proofs for the Existence of God
- A cosmological proof for the existence of God
derives Gods existence from facts established by
cosmology - Form of a cosmological argument
- By observation of the universe or parts of the
universe we know a posteriori that the universe
or parts thereof have property P - The best explanation of P is the hypothesis that
God exists. - Therefore, God does exist
6Aquinas Five Cosmological Arguments for Gods
Existence
- Argument from motion
- Argument from efficient causation
- Argument from possibility and necessity
- Argument from gradation
- Argument from governance
7Argument from motion
- There is motion.
- Motion involves the reduction from potentiality
to actuality. (eg an activated spring on the
garden gate) - So all motion was first potentiality.
- Only what is actualized in some regard can reduce
something from potentiality to actuality in that
regard. (eg, the squirrel that releases the
coiled spring on the gate) - Nothing can reduce itself from potentiality to
actuality. - Nothing can move itself.
- There cannot be an infinite sequence of movers.
- ? There must be an unmoved prime mover, i.e.
God.
8Argument from efficient causation
- The sensible world is full of the effects of
efficient causation. - Nothing can be an efficient cause of itself.
- If a things cause is absent, then it cannot
exist. - Efficient causes are ordered 1st -gt intermediate
-gt (ultimate) effect. - So without a first cause, there cannot be
(ultimate) effects. - ? So there must be a first efficient cause,
i.e. God.
9Problems with cosmological arguments
- The arguments from motion and efficient causation
deny that anything can move or cause itself
except God. However, what establishes this
exception? Rather, why should we not simply say
that the sequence of causes/movers is
historically infinite? - Also, Aquinas arguments do not demonstrate that
- a single thing is responsible
- the first cause in any way resembles the
Judeo-Christian god - the thing responsible still exists
10Argument from contingency and necessity
- Some natural things exist contingently.
- For each contingent thing, there is a time at
which it does not exist. - If everything were contingent there would be a
time in the past when nothing existed. - If there were such a time, then nothing would now
exist. - ? So, something must exist that is not
contingent but rather necessary and which gives
rise to all things. This necessary being is God.
11Problems with the contingency argument
- Even if each particular object in the history of
the universe exists contingently, it does not
follow that there must be a time when no
contingent objects exist.
12Argument from gradation
- Everything is comparable /commensurable with
respect to value and being. - There is a gradation in these properties,
especially value. That is, some things are
better than others. - One thing is better than another only if the
former is more similar to that which is perfect
than is the later. - So, since things are comparable with respect to
value, there must exist that which is perfect,
and this can only be God.
13Problem with gradation
- The third premise is critical to the argument.
However, this premise is dubious. What reason
secures that variation in value presupposes the
existence of the standard of perfection? Notice
that there are many examples of comparability
that do not presuppose the existence of the
relevant standard e.g. one thing can be taller
than another without it being the case that there
exists any (third) object on which the comparison
depends.
14Argument from governance
- Some natural unintelligent objects have purposes.
(E.g. the purpose of the heart is to pump blood
the purpose of the wing is to enable flight.) - Purpose is always the result of intelligence.
- The purpose of some natural unintelligent objects
was not established by any natural intelligent
being (such as a human). - ? So, there must be a supernatural intelligent
being responsible for such purpose, and this is
God.
15Problems with governance
- Is it correct that objects have purposes in the
sense required by the argument? - If objects do have purposes in the sense required
by the argument, might these purposes not be
established simply by the unintelligent processes
of evolutionary biology?