Intro to Philosophy

Review for Test 1Test: In your discussion labsWednesday, September 18th

What is Philosophy?What does it study?

Philosophy:

The study ofquestions that cannot be

answered solelyby appealing to sense experience

or mathematical calculation.

Main divisions within Philosophy:

• Metaphysics and Ontology (the study of what is real or what exists)

• Epistemology (the study of knowledge)

• Value Theory (the study of values)

• Logic (the study of reasoning)

Logic

An Argument:

A group of statements --where one or more of these

statements --(the premises)

purport to offer evidence for one particular statement

--(the conclusion).

Kinds of Arguments

Inductive:• Inductive arguments

are probabilistic. They attempt to show that if the premises are true, then the conclusion is probably true.

Deductive:• Deductive arguments are

not probabilistic. They attempt to show that if the premises are true, then the conclusion must be true. A successful deductive argument is called a “valid” argument.

Validity

• In a valid argument, the truth of the premises guarantees the truth of the conclusion.– I.e., if the premises are all true, then the conclusion must be true.• So, an argument can be valid even with false premises

and a false conclusion. What it cannot have is all true premises and a false conclusion.• Only deductive arguments strive for validity.

Validity is a formal property of arguments.

• All humans are mortal.• Jones is human.• So, Jones is mortal.– All A’s are B’s.– x is an A.– So, x is a B.

• All pigs can fly.• Kent Baldner is a pig.• So, Kent Baldner can fly.

In a reductio ad absurdum argument we begin by assuming the opposite of

what we are trying to prove.

We then derive a contradiction (an “absurdity”) from this assumption to

show that it cannot be true (and so that what we are trying to

prove must be true).

Reductio Ad Absurdum• To show that P is true.– Begin by assuming that P is false.– Show that this assumption (that P is false) leads to

a contradiction.• But anything that leads to a contradiction must be false.

– So, since the assumption that P is false leads to a contradiction, we can conclude that the assumption that P is false must itself be false.

• In other words, P must be true.

A priori vs. A posterioriKnowledge

Knowledge(How we know or justify that something is true; not how we

first learned it.)

A Priori• Claims that can be known to

be true (can be justified as true) without consulting sense experience.

• Examples:– All the bachelors in this room

are unmarried.

– 3+5=8

A Posteriori• Claims that can be known to

be true (can be justified as true) only by consulting sense experience.

• Examples:– There are bachelors in this

room.

– I have 8 coins in my pocket.

A priori vs. A posteriori

• The crucial difference between the two is not how we came to believe that some statement is true (how we learned it), but instead how we know (as opposed to merely believe) that the statement is true. How do we justify this belief? If we need sense experience to justify our belief that the statement is true, then it is a posteriori knowledge. If we can justify the belief as true without consulting sense experience, then it is a prioriknowledge.

A priori vs. A posteriori Arguments

• An argument is a priori if all of its premises are a priori, i.e., if their truth can be established without appeal to sense experience.

• An argument is a posteriori if at least one of its premises is a posteriori, i.e., if the truth of at least one premise can be established only by appeal to sense experience.

A priori vs. A posteriori Arguments

• Who cares?

• Since a priori arguments do not rely on sense experience to establish the truth of any of their premises, they cannot be refuted by any kind of perception or observation.

• A priori arguments are “conceptual” arguments, and so are independent of sense experience.

A priori vs. A posteriori

• Anselm’s “Ontological Argument” is an “a priori” argument.– This argument is unique. It is entirely conceptual, and does

not rely upon any empirical evidence.

• Aquinas’ “Cosmological Argument” is an “a posteriori” argument.– This argument is more familiar. It relies upon some things

we have learned about the world by means of our senses—i.e., it relies upon empirical evidence.

Anselm’s “Ontological”Argument for the existence

of God

Anselm’s conception of God:• A being than which none greater can be

conceived …– that is, a being such that one cannot conceive (or think)

of anything greater.

• Anselm argues that this being—a being than which none greater can be conceived—cannot not exist. – Its existence follows necessarily from the meaning of

the words.

Anselm’s Argument(in a nutshell)

• Claim: A being than which none greater can be conceived exists necessarily, i.e., its non-existence is impossible, because denying its existence involves a contradiction.

• Reasoning: To say that a being than which none greater can be conceived exists only in the understanding is to say that it would be greater if it existed in reality as well, which means that it (a being than which none greater can be conceived) is such that I can conceive of a greater being (the being it would be if existed in reality as well). And this is contradictory, and so impossible.

Existence in the Understanding• For Anselm, a thing “exists in the understanding” if

we understand what it would mean for that thing to exist in reality—if we understand the concept.– So, Santa Claus exists in the understanding, even though he

doesn’t exist in reality.• Atheism claims that God exists only in the

understanding, but not in reality as well. – According to Anselm’s argument, this belief directly entails

a contradiction, and so must be rejected as false.

Greatness-making properties:• What does it mean to say that one being is or isn’t

“greater” than another?– What makes a being “great?” What are “greatness-making properties?

• Anselm: “I do not mean physically great, but … better … or … more worthy.”

• For Anselm, existence is a “greatness-making property.” For any conceivable thing, this thing has more greatness if it exists in reality than if it doesn’t.

“On Behalf of the Fool”Gaunilo’s Challenge to Anselm

Gaunilo (in a nutshell)• Anselm argues that it is impossible that a being than

which none greater can be conceived exists only in the understanding, and not in reality as well.

• Gaunilo argues that if Anselm’s reasoning were correct (i.e., valid), it would also show that an islandthan which none greater can be conceived must also exist in reality.

• But clearly there is no such island. So something in Anselm’s reasoning must be faulty. Anselm’s argument must not be valid.

Gaunilo

• If Anselm’s argument were valid, then if it worked for “that being such that none greater is possible,” it must also work for “that island such that none greater is possible.”

• But, it doesn’t work for “that island such that none greater is possible.”

• So, the argument is not valid.

CosmologicalArguments:

Aquinas

Cosmology

• The science of cosmology studies physical theories about the origins of the material universe.

• Aquinas’ Cosmological Argument argues that we can explain the origins of the natural world only by appealing to a “supernatural” first cause or “uncaused causer.”

Aquinas’s Second Way:• 1. Some things are caused to exist.– And causes precede their effects.

• 2. Nothing can cause itself to exist. (If so, it would have to “precede itself.”)• 3. This cannot go on to infinity. – (If it did, there would be no first cause. And

without a first cause, nothing would be happening now. But things are happening now.)

• So, there must be a first cause—an uncaused causer.

What is wrong with this?

• Aquinas is trying to prove that there must be a first cause. The only alternative to this is that the sequences of causes goes backwards in time to infinity.

• He reasons that the series of causes cannot go backwards in time to infinity because, if it did, there would be no first cause.

• Therefore, he reasons, there must be a first cause.

Aquinas Begs the Question• Aquinas is trying to prove that there must be a “first

cause.”– He argues there must be a first cause because otherwise the

series of causes would to on to infinity.– He argues the series of causes cannot go on to infinity

because then there would be no first cause.

• This amounts to arguing that there must be a first cause because otherwise there wouldn’t be first cause.

CosmologicalArguments:

Clarke

Clarke’s Cosmological Argument• Aquinas didn’t seriously consider the possibility that

the universe might have had an infinitely long past history.– Whether or not it could have is the “question” he

“begged.”

• Clarke says that even if the universe has existed for eternity, we still need to posit the existence of God to explain the existence of the entire infinite series of causes and effects—that is, of the universe as a whole.

Clarke’s Cosmological Argument:

• 1. Suppose (for reductio) that everything there is is part of an infinite series of dependent things– (where each and every thing is dependent for its

existence upon the existence of some previous thing, ad infinitum.)

– that is, suppose that nothing (nothing outside the natural world) caused the world.

Clarke’s Cosmological Argument:

• 2. Then the series as a whole has no cause “from without” (because it is hypothesized to include everything there is), and

• 3. The series as a whole has no cause “from within” (If it had a cause from within, then that thing would be its own cause, making it a necessary being, violating the assumption that everything there is is part of an infinite series of dependent beings.).

Clarke’s Cosmological Argument:

• 4. So the whole series is without any cause.

• 5. But this cannot be, and so we must posit the existence of God to explain the existence of this infinite series.

Clarke’s Cosmological Argument

“´ c Æ” means causes“∞” means infinity

“D-n” means Dependent Event

An infinite series of dependent events:

What caused it?

∞ .... ´ c Æ D-3´ c Æ D-2´ cÆ D-1´cÆ Now0

How much can we explain?

• If every fact must have an explanation, where can we stop?– If we need God as an explanation of the infinite series,

don’t we need an explanation of God?– If some things (like God) don’t need an explanation,

why does the infinite series need an explanation?• Which is harder to accept?– That some facts cannot, even in principle, ever be

explained; or– That there must be some single being that explains

everything, including itself?

The Problemof Evil

The Problem of Evil:

• An all-powerful being would be able to prevent evil from happening in the world.

• An all-good being would want to prevent evil from happening in the world.

• Evil happens in the world.• Therefore, it must not be the case that any

being is both all-powerful and all-good.

Doesn’t Evil Exist in the World?

Theodicy:

• An explanation for why God, a being who is all good– (and so should want to prevent evil)

• and is also all-powerful – (and so should be able to prevent evil)

• nevertheless allows evil to exist in the world.

“Absence of Good” vs. “Positive Evil”

• The problem of evil, many theists say, concerns not the lack of perfect goodness in the world, but only the presence of real badness (“positive bad states”).

• The theist can admit that the world could be better in many ways. God, for the theist, is the source of all goodness, but is not obligated to create all the goodness she could have. So, the lack of perfect goodness in the world is not evidence against the existence of an all good and all powerful being.

Positive Badness (Real Evil)

• It is only the existence in the world of “positive evil” that the theist must explain.– These explanations, recall, are called

“theodicies.”• Swinburne divides “positive badness” into

two categories, and offers a different theodicy (explanation) for each. They are:–Moral Evil, and – Natural Evil.

Moral Evil vs. Natural Evil

Moral Evil

– All evil deliberately caused by human beingsdoing what is “wrong,” or not doing what is “right.”

• e.g., homicide; i.e., suffering caused by humans freely doing bad things:– i.e., by “sin.”

• Natural Evil

– All evil not deliberately caused by human beings (either directly, or through negligence).

• e.g., natural disasters; any suffering not caused by human choices.

The Free Will Defense

• In order for my free will to be meaningful, it must be possible for me to choose to hurtpeople as well as to help them.

• So, misusing our free will brings evil into the world.

• So this kind of “evil” is a necessary part of the greater good of creating a world in which human beings have a free will.

The Free Will Defense(regarding moral evil)

• “The possibility of humans bringing about significant evil is a logical consequence of their having this free and responsible choice. Not even God could give us this choice without the possibility of resulting evil.”– on this view, God does not create (moral) evil:• we do.

Natural Evil

• Natural evil (suffering not caused by a misuse of human free will) is a necessary part of achieving a “greater good.”

• It motivates us to understand the natural world (in order to prevent natural evils).

• And it provides opportunities for us to learn things like courage and compassion—it promotes human “moral growth.”

Best of All Possible Worlds?• German philosopher, Gottfried Leibniz, turned the

whole “problem” on it’s head:– There are many different ways that God could have

created the world.– Being all knowing, God foresaw everything that would

ever happen in each of these (infinitely many) “possible worlds.”

– Being all good, the world God chose to create must have been the one with the maximum amount of goodness.

– So, it not only follows that there isn’t any real evil, but that we live in the best of all possible worlds!

Swinburne’s Theodicy

• “Moral Evil” is caused by human freewill, not by God.– So, the “badness” humans cause is “outweighed”

by the goodness of our having free will.• “Natural Evil” is created by God because it is

needed in order for us to achieve a greater amount of goodness.– So, again, its “badness” is outweighed by a

greater goodness.

Why does God allow animals to suffer?

• “There is … no reason to suppose that animals have a free will.” [p.112]

• It is “reasonable to suppose” that animals suffer less than humans, and so “one does not need as powerful a theodicy as one does …[for] humans.”

• “For animals too … there are more worthwhile things” than pleasure, and these greater goods are possible only if natural evil is possible.

• So, like naturally caused human suffering, in the end it brings about more good than evil.

Study Hard!

• Review all the lecture notes, not just this review.

• Think before you answer the questions.– The questions are designed to require you to think

while taking the test, not just to remember.• Bring a #2 pencil.