Principles of Inquiry Discussion
project: The A Posteriori and the A Priori
Here
are several propositions. Try to decide
which of them can be known a priori
and which depend on evidence (and thus can be known only a posteriori):
- 2+3=5
- If you have two koalas
and three kangaroos, you have five animals.
- If Perth is west of
Adelaide and Adelaide is west of Sydney, then Perth is west of Sydney.
- Perth is west of
Sydney.
- George W. Bush is the
President of the United States.
- The President of the
United States has the power to veto legislation passed by Congress.
- No bachelor is married.
- No goose is purple.
- No goose is a fish.
- If you work hard, you
will succeed.
- If you lose all the
hair on your head, you will be bald.
- Everything that has a
color has a shape.
- Everything that has a
shape has a size.
Here
are several classical arguments for the existence of God. Try to decide which of them is a posteriori
and which a priori:
The Ontological Argument
- God is, by definition,
the most perfect being.
- A God that exists is
surely more perfect than a merely imaginary or fictional God.
- So, God exists.
The Argument from Design
- If we examine the
natural world we find many intricate and intricately related
structures. (Think, for example,
of the human eye and of the way our power of sight enables us to meet our
needs.)
- Quite generally, when
we find intricately structured objects we suppose that intelligent
designers created them. (Think,
for example, of finding an object on the beach, examining it, and
discovering that it was a working timepiece. Surely we would assume that it had been made by some
intelligent designer, not that it had just grown, like a seashell.)
- So, we should also
infer that the intricate structures in nature are the product of
intelligent design.
- So, God exists.
A Cosmological Argument
- It is a self-evident
truth that every event must have a cause.
- But the chain of cause
and effect cannot go on forever.
- So, there must be a
First Cause.
- So, God exists.