Philosophy Weeks 5 and 6
September 30, 2013
Guanilo’s criticism of Anselm’s argument: is a form of a reductio ad absurdum argument (form of modus
P1) ifAnselm’s argument is sound, then my perfect island argument is sound.
P2) My p-island argument is not sound; it’s absurd
C) Hence, Anselm’s ontological argument is unsound.
If the Earth was flat, you could sail off the edge
You can’t sail of the edge
Therefore, the Earth is not flat
Anselm: finite things, like islands, can’t be perfect.
E-unicorn analogy: another objection toAnselm’s ontological argument
Unicorns don’t exist in the actual world. But consider a new concept, which we can call an e-unicorn.An
e-unicorn is by definition an existing unicorn.
Does it follow from the idea of an E-unicorn that there are E-unicorns: certainly not.
- Slide: objections to ontological argument
There’s a reason to believe in God even if all the other arguments fail.
October 2, 2013
Ticket wins (1/1 000 000) Ticket loses (999 999/1 000 000)
Action #1 Buy ticket $100 000 - $1
Action #2 Don’t buy ticket / /
Expected value of action: (Gain of outcome #1 x probability of outcome 1) + (Gain of outcome #2 x
probability of outcome 2)
EV of action #1: (100 000)x(1/1 000 000) + (-1)(999 999/1 000 000)
EV of action #2: 0
0 is bigger, so if you’re interested in maximizing your expected monetary value, don’t buy ticket.
Expected Utility: expected magnitude of the satisfaction to your preferences. (could be happiness) Calculate the EU of an action by multiplying each possible outcome of a given action by its probability of
occurring and add up the weighted values for each possibility.
Evidential rationality vs. prudential rationality
Prudential rationality: An action is prudentially rational if it maximizes your expected utility.
Evidential rationality: believing all and only what the evidence indicates about the world.
God exists (prob: ½ or 1/100) No God exists (1/2 or 99/100)
Believe God exists Infinity Finite loss (-x)
Don’t believe God exists 0, or –infinity Finite gain (+x)
Expected utility of believing is God: infinity(1/100) + (-x)(99/100) = infinity
Expected utility of not believing in God: 0(1/100) + x(99/100) = x gain
Objections to Pascal’s Wager
Many Gods Objection:
Pascal is making an assumption about what God would be like if God exists.
Maybe God only rewards those who are evidentially rational and punishes those who are prudentially
rational, and thus the outcomes would be opposite to what Pascal is suggesting.
Consider that Gods Aand B don’t co-exist (monotheistic theory)
GodAexists God B No God exists
Believe GodA Infinity -infinity -x
Believe God B -infinity Infinity -x
No believe GodA -infinity Infinity x
If one makes different assumptions, you can get different answers to the questions of whether it’s prudent
to believe. If there’s even a small chance that a God B exists who infinitely punishes theists and infinitely
rewards atheists, then one may argue that it is prudentially rational NOT to believe in God.
William James: gives an argument for theism based on rationality: based on one’s own individual psyche.
Reassured by theism Not reassured by theism
Believe God exists +x (life has meaning, less fear of -x (life as a theist is torment,
death, etc.) limitation of theism
Don’t believe God exists -x (fear of death, life has no +x
meaning) These are focused on the consequences of belief in present life, not the afterlife.
October 4, 2013
The Problem o