philosophy of religion

Pascal’s wager

philosophy of religion – p. 1

Pascal and decision theory

bc

bc

bc

bc

bc

bc

philosophy of religion – p. 2

Pascal and decision theory

Blaise Pascal (1623–1662)

bc

bc

bc

bc

bc

bc

philosophy of religion – p. 2

Pascal and decision theory

Blaise Pascal (1623–1662)bc“We are all forced to gamble . . . ”

bc

bc

bc

bc

bc

philosophy of religion – p. 2

Pascal and decision theory

Blaise Pascal (1623–1662)bc“We are all forced to gamble . . . ”bcHow do we decide when the outcomes areuncertain?

bc

bc

bc

bc

philosophy of religion – p. 2

Pascal and decision theory

Blaise Pascal (1623–1662)bc“We are all forced to gamble . . . ”bcHow do we decide when the outcomes areuncertain?

bcDecision theory:

bc

bc

bc

philosophy of religion – p. 2

Pascal and decision theory

Blaise Pascal (1623–1662)bc“We are all forced to gamble . . . ”bcHow do we decide when the outcomes areuncertain?

bcDecision theory:bcRational agents seek to maximize the return ontheir investment.

bc

bc

philosophy of religion – p. 2

Pascal and decision theory

Blaise Pascal (1623–1662)bc“We are all forced to gamble . . . ”bcHow do we decide when the outcomes areuncertain?

bcDecision theory:bcRational agents seek to maximize the return ontheir investment.

bcRational decisions are possible if we know thepossible outcomes and the probabilities of thoseoutcomes.

bc

philosophy of religion – p. 2

Pascal and decision theory

Blaise Pascal (1623–1662)bc“We are all forced to gamble . . . ”bcHow do we decide when the outcomes areuncertain?

bcDecision theory:bcRational agents seek to maximize the return ontheir investment.

bcRational decisions are possible if we know thepossible outcomes and the probabilities of thoseoutcomes.

bcCan these ideas be applied to religious belief?

philosophy of religion – p. 2

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:

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

you

play

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

you

play

you don’t

play

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

you

play

you don’t

play

$100

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

you

play

you don’t

play

$100 $-1

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

you

play

you don’t

play

$100 $-1

$0

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

you

play

you don’t

play

$100 $-1

$0 $0

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

you

play

you don’t

play

$100 $-1

$0 $0

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

expected outcome if you play: (1/100 × $100) + (99/100 ×−$1) = $0.01

philosophy of religion – p. 3

a lottery

:

:

:

:

:

:

:

:

win

1/100

lose

99/100

you

play

you don’t

play

$100 $-1

$0 $0

Is it rational to play if 100 tickets are sold for $1 and the prize is $100 ?

expected outcome if you play: (1/100 × $100) + (99/100 ×−$1) = $0.01

if tickets cost $2: (1/99 × $100) + (99/100 ×−$2) = −$0.98

philosophy of religion – p. 3

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philosophy of religion – p. 4

Pascal’s wager

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:

philosophy of religion – p. 4

Pascal’s wager

:

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:

:

:

:

:

:

God

exists

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

you

believe

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

you

believe

you don’t

believe

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

you

believe

you don’t

believe

infinitegain

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

you

believe

you don’t

believe

infinitegain

smallloss

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

you

believe

you don’t

believe

infinitegain

smallloss

infiniteloss

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

you

believe

you don’t

believe

infinitegain

smallloss

infiniteloss

smallgain

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

you

believe

you don’t

believe

infinitegain

smallloss

infiniteloss

smallgain

expected outcome for belief: (? ×∞) + (? ×−something) = ∞

philosophy of religion – p. 4

Pascal’s wager

:

:

:

:

:

:

:

:

God

exists

God does

not exist

you

believe

you don’t

believe

infinitegain

smallloss

infiniteloss

smallgain

expected outcome for belief: (? ×∞) + (? ×−something) = ∞

expected outcome for non-belief: (? ×−∞) + (? × +something) = −∞

philosophy of religion – p. 4

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:

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:

:

philosophy of religion – p. 5

the other religions objection

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philosophy of religion – p. 5

the other religions objection

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Yaweh

exists

philosophy of religion – p. 5

the other religions objection

:

:

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:

Yaweh

exists

Allah

exists

philosophy of religion – p. 5

the other religions objection

:

:

:

:

:

:

:

:

Yaweh

exists

Allah

exists

you believe

in Yaweh

philosophy of religion – p. 5

the other religions objection

:

:

:

:

:

:

:

:

Yaweh

exists

Allah

exists

you believe

in Yaweh

you believe

in Allah

philosophy of religion – p. 5

the other religions objection

:

:

:

:

:

:

:

:

Yaweh

exists

Allah

exists

you believe

in Yaweh

you believe

in Allah

infinitegain

philosophy of religion – p. 5

the other religions objection

:

:

:

:

:

:

:

:

Yaweh

exists

Allah

exists

you believe

in Yaweh

you believe

in Allah

infinitegain

infiniteloss

philosophy of religion – p. 5

the other religions objection

:

:

:

:

:

:

:

:

Yaweh

exists

Allah

exists

you believe

in Yaweh

you believe

in Allah

infinitegain

infiniteloss

infiniteloss

philosophy of religion – p. 5

the other religions objection

:

:

:

:

:

:

:

:

Yaweh

exists

Allah

exists

you believe

in Yaweh

you believe

in Allah

infinitegain

infiniteloss

infiniteloss

infinitegain

philosophy of religion – p. 5

the other religions objection

:

:

:

:

:

:

:

:

Yaweh

exists

Allah

exists

you believe

in Yaweh

you believe

in Allah

infinitegain

infiniteloss

infiniteloss

infinitegain

expected outcome whoever you believe in: (? ×∞) + (? ×−∞) = 0

philosophy of religion – p. 5

belief and choice

bc

bc

bc

bc

bc

bc

bc

bc

philosophy of religion – p. 6

belief and choice

bcCan you believe something that you have noevidence for, even if you have an incentive to believe?

bc

bc

bc

bc

bc

bc

bc

philosophy of religion – p. 6

belief and choice

bcCan you believe something that you have noevidence for, even if you have an incentive to believe?

bcPascal’s answer:

bc

bc

bc

bc

bc

bc

philosophy of religion – p. 6

belief and choice

bcCan you believe something that you have noevidence for, even if you have an incentive to believe?

bcPascal’s answer:bcAct as if you believe . . .

bc

bc

bc

bc

bc

philosophy of religion – p. 6

belief and choice

bcCan you believe something that you have noevidence for, even if you have an incentive to believe?

bcPascal’s answer:bcAct as if you believe . . .

bcGo to church.

bc

bc

bc

bc

philosophy of religion – p. 6

belief and choice

bcCan you believe something that you have noevidence for, even if you have an incentive to believe?

bcPascal’s answer:bcAct as if you believe . . .

bcGo to church.bcAssociate with religious people.

bc

bc

bc

philosophy of religion – p. 6

belief and choice

bcCan you believe something that you have noevidence for, even if you have an incentive to believe?

bcPascal’s answer:bcAct as if you believe . . .

bcGo to church.bcAssociate with religious people.bcPray often.

bc

bc

philosophy of religion – p. 6

belief and choice

bcCan you believe something that you have noevidence for, even if you have an incentive to believe?

bcPascal’s answer:bcAct as if you believe . . .

bcGo to church.bcAssociate with religious people.bcPray often.

bc. . . do these things long enough and belief willcome.

bc

philosophy of religion – p. 6

belief and choice

bcCan you believe something that you have noevidence for, even if you have an incentive to believe?

bcPascal’s answer:bcAct as if you believe . . .

bcGo to church.bcAssociate with religious people.bcPray often.

bc. . . do these things long enough and belief willcome.

bcPrudential reasons for belief can override lack ofevidential reasons.

philosophy of religion – p. 6

self-deception and wishful thinking

bc

bc

bc

bc

bc

philosophy of religion – p. 7

self-deception and wishful thinking

“I know very well that my wife is having an affair, but I don’t want to

believe it . . . ”

bc

bc

bc

bc

bc

philosophy of religion – p. 7

self-deception and wishful thinking

“I know very well that my wife is having an affair, but I don’t want to

believe it . . . ”

“What can I do to convince myself that she’s not cheating on me?”

bc

bc

bc

bc

bc

philosophy of religion – p. 7

self-deception and wishful thinking

“I know very well that my wife is having an affair, but I don’t want to

believe it . . . ”

“What can I do to convince myself that she’s not cheating on me?”bc

Don’t look for evidence that supports what I don’t want to know.

bc

bc

bc

bc

philosophy of religion – p. 7

self-deception and wishful thinking

“I know very well that my wife is having an affair, but I don’t want to

believe it . . . ”

“What can I do to convince myself that she’s not cheating on me?”bc

Don’t look for evidence that supports what I don’t want to know.bc

Over-emphasize evidence in favor of my preferred view.

bc

bc

bc

philosophy of religion – p. 7

self-deception and wishful thinking

“I know very well that my wife is having an affair, but I don’t want to

believe it . . . ”

“What can I do to convince myself that she’s not cheating on me?”bc

Don’t look for evidence that supports what I don’t want to know.bc

Over-emphasize evidence in favor of my preferred view.bc

Come up with other interpretations of the evidence and treat

them as more likely.

bc

bc

philosophy of religion – p. 7

self-deception and wishful thinking

“I know very well that my wife is having an affair, but I don’t want to

believe it . . . ”

“What can I do to convince myself that she’s not cheating on me?”bc

Don’t look for evidence that supports what I don’t want to know.bc

Over-emphasize evidence in favor of my preferred view.bc

Come up with other interpretations of the evidence and treat

them as more likely.bc

Rely heavily on the opinions of people who haven’t seen the

evidence.

bc

philosophy of religion – p. 7

self-deception and wishful thinking

“I know very well that my wife is having an affair, but I don’t want to

believe it . . . ”

“What can I do to convince myself that she’s not cheating on me?”bc

Don’t look for evidence that supports what I don’t want to know.bc

Over-emphasize evidence in favor of my preferred view.bc

Come up with other interpretations of the evidence and treat

them as more likely.bc

Rely heavily on the opinions of people who haven’t seen the

evidence.

bcCan these methods be used deliberately? Or do they only work as

automatic, unconscious mechanisms?

philosophy of religion – p. 7

infinite payoffs?

bc

bc

bc

bc

bc

bc

bc

bc

philosophy of religion – p. 8

infinite payoffs?

bcDoes it make sense to talk about infinite rewards or punishments?

bc

bc

bc

bc

bc

bc

bc

philosophy of religion – p. 8

infinite payoffs?

bcDoes it make sense to talk about infinite rewards or punishments?bc

The St. Petersburg paradox

bc

bc

bc

bc

bc

bc

philosophy of religion – p. 8

infinite payoffs?

bcDoes it make sense to talk about infinite rewards or punishments?bc

The St. Petersburg paradoxbc

How much would you pay to play a game where you get $2n

for every n flips of a coin until a head comes up?

bc

bc

bc

bc

bc

philosophy of religion – p. 8

infinite payoffs?

bcDoes it make sense to talk about infinite rewards or punishments?bc

The St. Petersburg paradoxbc

How much would you pay to play a game where you get $2n

for every n flips of a coin until a head comes up?bc

The expected outcome is ((1/2) × 2) + ((1/4) × 4) + ((1/8) ×

8) + ((1/16) × 16) + ((1/32) × 32) + . . . = ∞

bc

bc

bc

bc

philosophy of religion – p. 8

infinite payoffs?

bcDoes it make sense to talk about infinite rewards or punishments?bc

The St. Petersburg paradoxbc

How much would you pay to play a game where you get $2n

for every n flips of a coin until a head comes up?bc

The expected outcome is ((1/2) × 2) + ((1/4) × 4) + ((1/8) ×

8) + ((1/16) × 16) + ((1/32) × 32) + . . . = ∞

bcIf we spent eternity alternating between 5 minutes of bliss and 5

mintues of torture, we would experience both infinite bliss and

infinite torture.

bc

bc

bc

philosophy of religion – p. 8

infinite payoffs?

bcDoes it make sense to talk about infinite rewards or punishments?bc

The St. Petersburg paradoxbc

How much would you pay to play a game where you get $2n

for every n flips of a coin until a head comes up?bc

The expected outcome is ((1/2) × 2) + ((1/4) × 4) + ((1/8) ×

8) + ((1/16) × 16) + ((1/32) × 32) + . . . = ∞

bcIf we spent eternity alternating between 5 minutes of bliss and 5

mintues of torture, we would experience both infinite bliss and

infinite torture.

bcIs anything we do ever enough to deserve an infinite payoff?

bc

bc

philosophy of religion – p. 8

infinite payoffs?

bcDoes it make sense to talk about infinite rewards or punishments?bc

The St. Petersburg paradoxbc

How much would you pay to play a game where you get $2n

for every n flips of a coin until a head comes up?bc

The expected outcome is ((1/2) × 2) + ((1/4) × 4) + ((1/8) ×

8) + ((1/16) × 16) + ((1/32) × 32) + . . . = ∞

bcIf we spent eternity alternating between 5 minutes of bliss and 5

mintues of torture, we would experience both infinite bliss and

infinite torture.

bcIs anything we do ever enough to deserve an infinite payoff?bc

Justice requires proportionality – worse crimes get worse

punishments.

bc

philosophy of religion – p. 8

infinite payoffs?

bcDoes it make sense to talk about infinite rewards or punishments?bc

The St. Petersburg paradoxbc

How much would you pay to play a game where you get $2n

for every n flips of a coin until a head comes up?bc

The expected outcome is ((1/2) × 2) + ((1/4) × 4) + ((1/8) ×

8) + ((1/16) × 16) + ((1/32) × 32) + . . . = ∞

bcIf we spent eternity alternating between 5 minutes of bliss and 5

mintues of torture, we would experience both infinite bliss and

infinite torture.

bcIs anything we do ever enough to deserve an infinite payoff?bc

Justice requires proportionality – worse crimes get worse

punishments.bc

But infinite reward or punishment cannot be proportional to any

finite act.

philosophy of religion – p. 8

Kant’s moral argument

philosophy of religion – p. 9

Kant’s moral argument

Either there are moral absolutes or anything goes.

philosophy of religion – p. 9

Kant’s moral argument

Either there are moral absolutes or anything goes.

But it is not true that anything goes – it is just plain wrong to kill

babies for fun.

philosophy of religion – p. 9

Kant’s moral argument

Either there are moral absolutes or anything goes.

But it is not true that anything goes – it is just plain wrong to kill

babies for fun.

So there must be moral absolutes.

philosophy of religion – p. 9

Kant’s moral argument

Either there are moral absolutes or anything goes.

But it is not true that anything goes – it is just plain wrong to kill

babies for fun.

So there must be moral absolutes.

In order to make sense of moral absolutes we must suppose that

there is a good God who is responsible for creating and enforcing

moral rules.

philosophy of religion – p. 9

Kant’s moral argument

Either there are moral absolutes or anything goes.

But it is not true that anything goes – it is just plain wrong to kill

babies for fun.

So there must be moral absolutes.

In order to make sense of moral absolutes we must suppose that

there is a good God who is responsible for creating and enforcing

moral rules.

So we must suppose that there is such a God, even if there is

absolutely no evidence that He or She exists.

philosophy of religion – p. 9