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Does God exist?. Outline. Is there any point to debating God? Three classic arguments for the existence of God Miracles and other testimonial evidence Faith and reason Arguments against God’s existence: The problem of evil and the scale of the universe Conclusions. Defining the issue.

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  • Is there any point to debating God?

  • Three classic arguments for the existence of God

  • Miracles and other testimonial evidence

  • Faith and reason

  • Arguments against God’s existence: The problem of evil and the scale of the universe

  • Conclusions

Defining the issue
Defining the issue

Concept of God in western monotheism:

  • God created the universe.

  • God is all powerful (omnipotent).

  • God is all knowing (omniscient).

  • God is perfectly good.

  • God is a person-like entity.

  • God is eternal and not dependent on anything other than itself.

    Does this being exist?

Does god exist1
Does God exist?

  • Many people suggest that this question cannot be successfully answered.

  • Why? Because:

    • “You can’t prove it.”

    • “It’s a matter of opinion/it’s subjective.”

    • “Nobody ever changes their mind about religion.”

Nobody changes their mind
Nobody changes their mind?

  • This objection is false.

  • People are not born with beliefs about God, so to get beliefs about God people must change their minds!

  • People are convinced, often when they are small children.

  • Or as adults, by arguments: for or against.

  • Or by appeals to authority (parents, priests, the Bible).

Is god exists subjective
Is “God exists” subjective?

  • Recall the definition of “subjective”.

  • Aclaim is subjective if whether it is true or false depends on what someone thinks, feels, or believes.

  • So: “I feel sad”, “My dog is hungry”, “Most Americans think we should get out of Iraq”, and “I believe in God” are all subjective.

  • They are all claims about mental states.

The objectivity of the issue
The objectivity of the issue

  • Subjective claims tell us about what is going on inside someone’s head.

  • “I loved that movie”, e.g., doesn’t tell us about the movie, it tells us what someone feels about the movie.

  • Likewise, “I believe in God” doesn’t tell us about God, it tells us about the speaker.

  • But we’re interested in God, not what people thinkabout God.

Can t prove it
Can’t prove it?

  • You’d have to make an argument to show that God’s existence can’t be proven.

  • “There’s no proof.”

  • But if there’s no proof, then why do so many people believe God exists?

  • If there was truly noproof, then not very many people would believe God exists.

  • (Cf. Batman, or the Tooth Fairy.)


  • People don’t usually have beliefs without any proof at all.

  • Rather, people have beliefs because of evidence or proof, that is, arguments.

  • So it isn’t true to say that there is no proof. If people believe it because of reasons, they think there’s enoughproof – at least, enough to convince themselves.

  • The proof may or may not be good, but to tell we’d have to consider the arguments!

What kind of proof
What kind of proof?

  • One reason people think there’s no proof is because God is not visible or tangible.

  • If someone asks: “does this marker exist”, you wouldn’t be convinced unless you saw it, or touched it, etc.

  • But you can’t see or touch God (or at least, most people don’t think so: notice how we treat anyone who claims to have met God in person).

Invisible intangible etc
Invisible, intangible, etc.

  • But we believe in the existence of many things that we can never see or touch.

    • Other people’s feelings

    • X-rays, electrons, and other scientific entities

    • Historical events

    • Mathematical truths

  • We believe that some claims about such things are true and some are false.

  • We decide which are true based on reasons.

  • We do the same with religious beliefs: we use reason. We don’t “just believe it”.

No proof
No proof?

  • And evenif there was no proof about God’s existence, that would not mean that it’s therefore reasonable to believe whatever you want to believe about God.

  • You have no proof about how much change is in my car, but that doesn’t mean it’s reasonable for you to believe I have $100 in change in my car.

No proof1
No proof?

  • Suppose someone accuses you of abusing children, but the person accusing you has no proof to support his allegation.

  • Is it reasonable for your accuser, or other people, to believe that you abuse children, even though they have no proof? No.

  • So “no proof” = not a good reason to believe God exists!

No proof2
No proof?

  • No proof ≠ it’s reasonable to believe whatever you want

  • No proof = you don’t know; you should suspend judgment.

Three classic arguments for god s existence
Three classic arguments for God’s existence

  • The First Cause Argument

    • (a.k.a. the Cosmological Argument)

  • The Design Argument

    • (a.k.a. the Teleological Argument)

  • The Ontological Argument

Aquinas s argument from efficient causality
Aquinas’s Argument from Efficient Causality

  • “The second way is based on the nature of causation. In the observable world, causes are to be found ordered in series; we never observe, or even could observe, something causing itself, for this would mean it preceded itself, and this is impossible.”

Aquinas s causality argument
Aquinas’s Causality Argument

  • “Such a series of causes, however, must stop somewhere. For in all series of causes, an earlier member causes an intermediate, and the intermediate a last (whether the intermediate be one or many). If you eliminate a cause you also eliminate its effects. Therefore there can be neither a last nor an intermediate cause unless there is a first. But if the series of causes goes on to infinity, and there is no first cause, there would be neither intermediate causes nor a final effect, which is patently false.”

Aquinas s causality argument1
Aquinas’s Causality Argument all call ‘God’.”

  • Let A be the current state of the world

  • It was caused, as was its cause, etc.

  • . . . → E → D → C → B → A

  • This can’t go on to infinity, or we’d never have gotten A in the first place.

  • So, there must be a first cause, God.

  • God → . . . → C → B → A

The first cause argument simplified a valid argument
The First Cause Argument (simplified; a valid argument) all call ‘God’.”

  • Everything has a cause.

  • So, the universe has a cause.

  • The only thing that could be the cause of the universe is God.

  • So, God exists.

An objection to first cause arguments why not infinity
An objection to First Cause Arguments: why not infinity? all call ‘God’.”

Aquinas doesn’t give any good argument why there can’t be infinite causal chains extending backwards in time.

........ → E → D → C → B → A → ........

After all, we seem to accept such chains for the future.

Another objection the central premise is inconsistently applied
Another objection: the central premise is inconsistently applied

  • If everything must have a cause, that implies that God had a cause.

  • The argument is not consistent: the definition of God contradicts its first premise.


Planet Earth formed

Big Bang


The unmoved mover
The unmoved mover? applied

  • Now, the traditional answer to this objection (that the premise implies that God must have a cause) is to say that God is an exception to the premise that ‘everything has a cause.’

  • God is said to be a “necessary being,” or the uncaused origin of causes.

  • But…

Why not other exceptions
Why not other exceptions? applied

If we’re okay with God having no cause, then why aren’t we okay with the universe having no cause? It may be a brute, necessary fact that the universe exists.

Humans evolved

Big Bang

Planet Earth formed


The inconsistency of first cause arguments
The inconsistency of First Cause Arguments applied

In other words:

A: “Where did the universe come from? It couldn’t just come from nowhere. So God made it.”

B: “But where did God come from?”

A: “Well, God just is.”

B: “Okay, then, why can’t the universe just be?”

A third objection to first cause arguments
A third objection to First Cause Arguments applied

The argument does not get us close to the God of traditional religion.

  • Why should we worship a First Cause?

  • Why should we think it is good? Or omniscient or omnipotent?

  • Why should we think it cares about earth or its inhabitants?

  • Why should we think that it still exists?

The design argument
The Design Argument applied

William Paley (1743-1805)

  • Suppose you find a watch

    • It’s complex (lots of parts working together)

    • Successful (the parts succeed in telling time)

  • You’d infer that it had an intelligent maker

  • Similarly, you find things in nature

    • Complex (human organs)

    • Successful (living things)

  • You should infer it had an intelligent maker, God

The design argument simplified a valid argument
The Design Argument (simplified; a valid argument) applied

  • Anything as complex as a human machine must be made by a human-like designer.

  • There are things in nature more complex than any human machine.

  • Therefore, there is a human-like (super-human) designer of parts of nature.

  • The only possible human-like designer of parts of nature is God.

Hume s criticisms
Hume’s Criticisms applied

Analogy is weak:

  • We know a watch is made by someone because it differs from what we find in nature

  • We can’t compare to other universes

  • Why is nature like a machine, rather than animal or vegetable?

Hume s criticisms1
Hume’s Criticisms applied

If the analogy was strong:

  • Lots of mistakes and conflicts in nature

  • Maybe earlier, botched universes

  • Many gods

  • Implies God is human-like: not perfect

The key premise
The key premise applied

“Anything as complex as a human machine must be made by a human-like designer.”

  • Is this plausible?

  • Are there good reasons to believe it?

  • Could there be good reasons to reject it?

An alternative explanation of natural complexity
An alternative explanation of natural complexity applied

  • Natural selection shows how animals and plants can be complex and successful without any conscious design.

  • Bacteria, for example, don’t need to be consciously designed to develop resistance to antibiotics.

  • Giraffes don’t need to be designed to have long necks.

  • And evolution also explains flaws in nature, which the Design Argument fails to do.

A major problem again
A major problem (again) applied

  • Just like the First Cause Argument, even if the Design Argument were good, the God it argues for is still far from the God of Christianity or Islam.

  • It would only be a vaguely human-like designer, and need not be good, or all-knowing, or even still exist.

A fine tuning argument
A Fine-Tuning Argument applied

  • If the laws of physics were even a tiny bit different, there would be no way for life or the universe as we know it to exist.

  • It is extremely unlikely that this would happen by chance.

  • If the laws of physics didn’t happen by chance, they must have been designed.

  • The laws of physics could only be designed by God.

Objections to fine tuning
Objections to fine-tuning applied

  • But all knowledge of probability comes from experience.

  • And we have no experience of laws of physics other than the ones we know.

  • So we don’t know if the laws of physics could have been different.

  • Since we don’t know what the probabilities are, we can’t assume whether the laws of physics were unlikely or not.

The weak anthropic principle
The weak anthropic principle applied

  • A different objection to fine-tuning arguments is to say it is not unlikely at all that the laws of physics are “just right”, given that we exist.

  • This is because if the laws of physics were not “just right”, then we wouldn’t exist.

  • So a fine-tuning argument is like someone saying “the odds of me being in this seat, in this room, in this building, in this city, in this country, etc., are very unlikely, so some God must have designed me to be here now.”

The ontological argument
The ontological argument applied

Anselm of Canterbury (1033-1109)

  • God is a being greater than which nothing which can be conceived.

  • I can conceive of such a being.

  • It is greater to exist in reality than only in imagination.

  • So, the being of which I conceive must exist in reality.

Anselm s ontological argument
Anselm’s ontological argument applied

  • We can conceive of a being than which none greater can be conceived.

  • Whatever is conceived exists in the mind.

  • That which exists in the mind and exists in reality is greater than a similar thing that exists only in the mind.

  • Thus, a being than which none greater can be conceived, exists in reality.

Gaunilo s criticism
Gaunilo’s criticism applied

  • ‘Islandia’ is an island greater than which no island can be conceived.

  • We can conceive such an island.

  • So the greatest conceivable island exists in our understanding.

  • But Islandia must exist in reality as well.

  • For if it did not, we could imagine a greater island – namely, one that existed in reality – and the greatest conceivable island would not be the greatest conceivable island after all.

  • But it is absurd to suppose that Islandia actually exists. Gaunilo concludes: Anselm's reasoning is bad.

Criticizing the ontological argument
Criticizing the ontological argument applied

  • The first premise is dubious: ‘We can conceive of a being than which none greater can be conceived.’ We can’t conceive of a number greater than any number.

  • The concepts of ‘perfection’ or ‘greater than’ are too vague to give any proof.

  • And existence isn’t like other predicates: to be perfect, you have to first be.

Testimonial evidence
Testimonial evidence applied

  • Those are the classic philosophical arguments. However, they don’t have a strong connection with the actual religious beliefs of Christianity, Judaism, etc.

  • One argument for traditional religious belief is a lot simpler: appeal to the miraculous events recorded in the Bible or the Koran.

A very simple argument from testimony
A very simple argument from testimony applied

  • The Bible says God exists.

  • The Bible is true.

  • Therefore, God exists.

Another argument from testimony
Another argument from testimony applied

  • The Koran says Jesus was not God.

  • The Koran is true.

  • Therefore, Jesus was not God.

    Whatever reasoning is used to criticize this argument applies equally well to the appeal to another (such as the appeal to the Bible).

Contradictory testimonies
Contradictory testimonies applied


  • Jesus of Nazareth is (the son of) God.

  • Jesus rose from the dead.

  • Mohammed was not a true prophet and did not visit heaven.

    Islam and Judaism:

  • Jesus is not (the son of) God.

  • Jesus did not rise from the dead.

Contradictory testimonies1
Contradictory testimonies applied

  • Given such religious claims:

    • Which of these claims are true?

    • Which of these claims should you believe?

  • They can’t all be true, and they can’t all be believed. So some of us have religious beliefs that are false.

  • Indeed, we already think many beliefs about religion are false.

Sathya sai baba
Sathya Sai Baba applied

  • Sathya Sai Baba is a “Godman”, born in 1926 in south India. He has around 6 million followers.

  • His mother supposedly became pregnant after a huge ball of blue light entered her.

Sathya sai baba1
Sathya Sai Baba applied

  • At 13, Sai Baba entered a coma, left his body, and returned reciting ancient religious chants. At 14, he threw away his school books and announced that “My devotees are calling me. I have my work.”

  • Sai Baba has:

  • Taken illnesses onto himself

  • Created holy ash, food, rings, necklaces, watches, spices, holy water, gold statues of gods, sugar candy, fruits, pastries (hot and cold), gems, colored string, and books out of thin air.

Sathya sai baba2
Sathya Sai Baba applied

Sai Baba has also:

  • levitated, bilocated, disappeared, changed granite into candy, changed water into gasoline, changed the color of his robe while wearing it, multiplied food, made different fruit appear on trees from actual stems, physically transformed into deities, and emitted brilliant light.

Sathya sai baba3
Sathya Sai Baba applied

  • So why don’t you believe that Sai Baba is a God-man? (Or all god now, since he left his body behind in 2011.)

  • Do you apply those same reasons to other religious beliefs?

Evaluating testimony
Evaluating testimony applied

It seems like there are two possibilities:

  • Sai Baba really does perform miracles.

  • Sai Baba has fooled people into thinking he performs miracles.

    Which of these is more likely?

Hume s argument against believing miracles

For a possible miracle, what is appliedmorelikely:

(1) someone made a mistake, lied, or there is an explanation; or

(2) it was a miracle.

As a miracle contradicts natural laws (supported by all experience), there will always be more support for (1) than (2).

Hume’s argument against believing miracles

Hume on miracles
Hume on miracles applied

Hume also points out that

  • people like stories about fantastic events

  • people want to believe miracles

  • miracle stories tend to start among the most ignorant

Hume on miracles1
Hume on miracles applied

  • Besides criticizing the plausibility of any possible report of miracles, Hume also criticizes existing reports of miracles.

  • The historical miracles of the major religions are reported, not by unbiased observers, but by a handful of people who wanted to believe them. The accounts came from largely illiterate and very superstitious societies. (Also, in the case of the Bible, we do not have first-hand reports of the witnesses, only versions written 30-100 years afterwards.)

Testimonial arguments and miracles conclusions
Testimonial arguments and miracles: conclusions applied

Is the testimony in the Koran weaker than the testimony in the New Testament? Or the Book of Mormon? Or the Bhagavad-Gita? They can’t all be correct. So many major bodies of religious testimony must be false.

Since we already reject lots of supposed miracles because their evidence is weak, we’re being inconsistent if we accept other, equally unproven testimony or miracles as true.

We are all atheists about most religions.

Faith applied

  • A possible definition of faith:

    • Trust in a special source of knowledge, usually related to religious belief, not subject to correction by reason or evidence.

  • “I just know it’s true.”

  • Religion based on faith, then, would be different from any other type of claim. It is not based on reason, and needs no proof.

Alvin Plantinga defends something similar to faith. He argues that “God exists” is a basic belief. By ‘basic belief’, he means it’s a belief that it makes sense to accept as true, even though we can’t give more basic reasons to think it’s true. Other basic beliefs include “other people have minds”, “there is a physical world”, “the past is real”, “my memories are not entirely false”, etc.

Plantinga argues that “God exists” is a :

“God has created us that we have a tendency or disposition to see his hand in the world around us. More precisely, there is in us a disposition to believe propositions of the sort ‘this flower was created by God’ or ‘this vast and intricate universe was created by God’ when we contemplate the flower or behold the starry heavens or think about the vast reaches of the universe.”

Could religion be a basic belief
Could religion be a basic belief? argues that “God exists” is a

  • Is religion a basic belief? Plantinga’s other examples of basic beliefs are “other people have minds”, “there is a physical world”, “the past happened”, etc.

  • No one seriously disagrees with those beliefs.

  • But lots of people seriously disagree about whether God exists.

Problems with accepting claims on faith
Problems with accepting claims on faith argues that “God exists” is a

Outside of religion, belief with no good reason is usually foolish (or worse), since it could easily justify false belief.

For example:

  • Accusations with no proof

  • Racial stereotypes or prejudices

  • Wild conspiracy theories

  • Wishful thinking

Problems with accepting claims on faith1
Problems with accepting claims on faith argues that “God exists” is a

  • And even in religion, we consider belief without good reason to be unwise or dangerous.

  • We routinely reject the sincere faith of believers in other religions, because we think it’s false. So we already admit that faith can easily lead to false beliefs, in religion as in everything else.

Faith s dangers
Faith’s dangers argues that “God exists” is a

And people who believe without any reason and refuse to listen to rational discussion are capable of believing and doing anything: sometimes this is quite dangerous.

Defending basic belief
Defending basic belief argues that “God exists” is a

  • A defender of faith as basic belief has to respond to the criticism that it allows people to believe anything. Plantinga calls this the “Great Pumpkin Objection.”

  • Plantinga’s answer is no one takes irrational beliefs such as the GP as basic.

  • But lots of people do take beliefs that contradict Christianity as basic (Islam, Hinduism, voodoo).

You don t believe in faith
You don’t believe in faith argues that “God exists” is a

Some Muslim thinks “I sincerely know my religion is true by faith.”

Some Christian thinks the same thing.

So at least one of them has a false belief due to faith.

So faith easily leads to false beliefs.

So faith isn’t a good reason to say a religious belief is true.

Conclusions argues that “God exists” is a

  • There is a point to trying to reason about God. It’s not impossible, and it’s not just wasting time, going around in circles.

  • Look at the discussion of each major argument. It wasn’t random.

  • We only have beliefs in the first place because we think there are good enough reasons to convince us.

  • You already do it. (Everyone rejects a lot of religious beliefs byreasoning already.)

Conclusions argues that “God exists” is a

  • The classic philosophical arguments for the existence of God rest on dubious premises, and even if successful, don’t prove traditional religious beliefs.

  • Traditional religious beliefs are based mostly on testimonial arguments. But we already reject testimonial arguments when we don’t like them (from different cultures), recognizing they are bad reasons.

Conclusions argues that “God exists” is a

  • Faith is a license to believe anything. Like testimony, we reject faith all the time. So if you reject the Sai Baba follower’s faith, then you already admit that faith is a weak reason to believe a claim is true.

  • So: neither the philosophical proofs, testimony, nor faith give good evidence that God exists.

  • (73% of philosophers are atheists, 15% theists, 12% “other.”)