about one of the foundational ideas of modern psychology.

This is what Francis Crick described as "The Astonishing

Hypothesis," the idea that our mental life,

our consciousness, our morality,

our capacity to make decisions and judgments is the product of

a material physical brain. What I want to talk about today

and introduce it, and it's going to be a theme

that we're going to continue throughout the rest of the

course, is a second idea which I think

is equally shocking, perhaps more shocking.

And this has to do with where mental life comes from,

not necessary its material nature, but rather its origin.

And the notion, this other "astonishing

hypothesis," is what the philosopher Daniel Dennett has

described as Darwin's dangerous idea.

And this is the modern biological account of the origin

of biological phenomena including psychological

phenomena. Now, people have long been

interested in the evolution of complicated things.

And there is an argument that's been repeated throughout history

and many people have found it deeply compelling,

including Darwin himself. Darwin, as he wrote The

Origin of Species, was deeply persuaded and moved by

this argument from--in the form presented by the theologian

William Paley. So, Paley has an example here.

Paley tells--gives the example of you're walking down the beach

and your foot hits a rock. And then you wonder,

"Where did that rock come from?"

And you don't really expect an interesting answer to that

question. Maybe it was always there.

Maybe it fell from the sky. Who cares?

But suppose you found a watch on the ground and then you asked

where the watch had come from. Paley points out that it would

not be satisfying to simply say it's always been there or it

came there as an accident. And he uses this comparison to

make a point, which is a watch is a very

complicated and interesting thing.

Paley is--was a medical doctor and Paley goes on to describe a

watch and compare a watch to the eye and noticing that a watch

and the eye contain multitudes of parts that interact in

complicated ways to do interesting things.

In fact, to change and to update the analogy a little bit,

an eye is very much like a machine known as a camera.

And they're similar at a deep way.

They both have lenses that bend light and project an image onto

a light-sensitive surface. For the eye the light-sensitive

surface is the retina. For the camera it's the film.

They both have a focusing mechanism.

For the eye it's muscles that change the shape of the lens.

For a camera it's a diaphragm that governs the amount of

incoming light. Even they're both encased in

black. The light-sensitive part of the

eye and part of the camera are both encased in black.

The difference is--So in fact, the eye and a camera look a lot

alike and we know the camera is an artifact.

The camera has been constructed by an intelligent--by

intelligent beings to fulfill a purpose.

In fact, if there's any difference between things like

the eye and things like a camera,

the difference is that things like the eye are far more

complicated than things like the camera.

When I was a kid I had this incredible TV show called "The

Six Million Dollar Man." Anybody here ever seen it or

heard of it? Oh.

Anyway, the idea is there's a test pilot, Steve Austin,

and his rocket jet crashes and he loses his--both legs,

his arm and his eye, which sounds really bad but

they replace them with bionic stuff,

with artificial leg, artificial arm and an

artificial eye that are really super-powered.

And then he fights crime. [laughter]

It was [laughs] really the best show on.

It was really good, [laughter]

but the thing is this was in 1974.

It's now over thirty years later and it's true then and

it's true now, this is fantasy.

It doesn't make it to the level of science fiction.

It's fantasy. We are impossibly far away from

developing machines that could do this.

We are impossibly far away from building a machine that can do

what the human eye does. And so somebody like Paley

points out, "Look. The complexity of the

biological world suggests that these things are complicated

artifacts created by a designer far smarter than any human

engineer. And the designer,

of course, would be God." I went to Goggle Images.

That--I don't mean that to be sacrilegious [laughter]

in any sense. You could try this.

I went to "Google Images" and typed in "God" and this is what

showed up right in the middle so--And this,

Paley argued, and it was--has been convincing

throughout most of history, is a perfectly logical

explanation for where these complicated things come from.

It also has the advantage of being compatible with scripture

and compatible with religious beliefs, but Paley made the

point this stands on its own. If you find complicated things

that--complicated artifacts, you don't assume they emerged

by accident. You assume that they were

created by an intelligent being. Now, this view has always had

problems. This view, you could call it

"creationism," which is that biological structures were

created by an intelligent being, has always had problems.

One problem is it pushes back the question.

So you ask, "Where did that intelligent being come from?"

And this is a particularly serious problem from the

standpoint of the evolution of psychological structures.

So, we want to know, "how is it that creatures came

across--upon this earth with the ability to reason and plan and

do things?" And then the answer is "well,

another creature with that ability created us."

That doesn't necessarily mean it's wrong, but it means it's

unsatisfying. You immediately want to get an

explanation for where that other creature comes from.

More to the point, there's always been evidence

for evolution. And what I mean by evolution

here isn't necessarily a specific mechanism,

but merely the fact that body parts like the eye didn't emerge

all of a sudden, but rather have parallels both

within other existing animals and across human and biological

history. This evidence comes in

different forms. There is fossil evidence for

different body parts suggesting that they have evolved from more

rudimentary form. There is vestigial

characteristics. And what this means is there

are characteristics that human bodies have that are somewhat

inexplicable, like the human tailbone or

goose-bumps, unless you view them--the human body in its

current form as modifications from a previous form.

There are parallels with other animals.

And this is clear in psychology. So, a human brain is different

from the rat, cat, and monkey brain but at

the same time you see them following a sort of common plan

and common structures. And one rational inference from

this is that they're linked through evolutionary descent.

Finally, there is occasional poor design.

So, Paley rhapsodized about the remarkable powers of the human

body and the different body parts,

but even Paley admitted that there are some things which just

don't work very well. Your eye contains a blind spot

because of how the nerves are wired up.

In the male urinary system the urethra goes through the

prostate gland instead of around it,

which leads to many physical problems in men later on in

life. And so you're forced to either

argue that these are really good things or that God is either

malicious or incompetent. And those are difficult

arguments to make. So, these are problems with the

creationist view. But still, for the longest time

in human intellectual history there was no alternative.

And in fact, Richard Dawkins,

the most prominent evolutionary--one of the most

prominent evolutionary biologists alive and one of the

most staunchest critics of creationism,

has written in The Blind Watchmaker saying,

look, anybody 100 years ago or 150 years ago who didn't believe

that God created humans and other animals was a moron

because the argument from design is a damn good argument.

And in the absence of some other argument you should

go--defer to that. You should say,

"Well, there are all of these problems but humans and other

biological forms must have divine creation because of their

incredible rich and intricate structure."

What changed all that of course was Darwin.

And Darwin--Darwin's profound accomplishment was showing how

you get these complicated biological structures,

like the eye, emerging through a purely

non-intentional, non-created process,

a purely physical process. And this could be seen as equal

in importance to the claim that the Earth revolves around the

Sun and that we're not the center of the universe.

And in fact, some scholars have made a

suggestion which seems plausible, that the idea of

natural selection is the most important idea in the sciences,

period. So, this is not a course in

evolution and I expect people to have some background.

If you don't have a background in it, you could get your

background from external readings but also from--the Gray

textbook and the Norton readings will both--will each provide you

with enough background to get up to speed.

But the general idea is that there are three components to

natural selection. There is variation.

And this variation gives rise to different degrees of survival

and reproduction and gets passed on from generation to generation

and gives rise to adaptations, what Darwin described as "that

perfection of structure that justly excites our imagination."

And the biological world has all sorts of examples.

You look at camouflage. Prior to Darwin one might

imagine that some intelligent creator crafted animals to hide

from their prey. But now we have a different

alternative, which is that animals that were better hidden

survive better, reproduce more,

and over the course of thousands, perhaps millions of

years, they've developed elaborate

camouflage. There's been a lot of work on

Paley's favorite example – the eye.

So Darwin himself noted that the human eye did not seem to

emerge all at once but rather you could look at other animals

and find parallels in other animals that seem to suggest

that more rudimentary forms are possible.

And more recently computer simulations have developed--have

been developed that have crafted eyes under plausible assumptions

of selective pressure and what the starting point is.

So, this is the theory of natural selection.

The good question to ask is, "why am I talking about

evolution in Introduction to Psychology class?"

And the answer is that there are two ideas which come

together. And in fact,

they're both of the dangerous ideas.

One idea is that Darwin's idea--that biological forms

evolve through this purely physical process.

The second idea, the rejection of Descartes,

is that our minds are the product of physical things and

physical events. You bring these together and it

forces you to the perspective that what we are--our mental

life is no less than the eye, no less than camouflage,

the product of this purely physical process of natural

selection. More to the point,

our cognitive mechanisms were evolved not to please God,

not as random accidents, but rather for the purpose of

survival and reproduction. More contentiously,

you could argue they've been shaped by natural selection to

solve certain problems. And so, from an evolutionary

point of view, when you look at what the brain

is and what the brain does, you look at it in terms of

these problems. And this is what psychology is

for. This is what our thinking is

for. We have evolved mental

capacities to solve different problems: perception of the

world, communication, getting nutrition and rest,

and so on. Now, we're going to talk about

how to apply evolutionary theory to psychology.

But as we're doing so we have to keep in mind two

misconceptions. There are two ways you can go

seriously wrong here. The first is to think that,

well, if we're taking an evolutionary approach then

natural selection will cause animals to want to spread their

genes. So, if we're being biological

about it, that means everybody must run around thinking "I want

to spread my genes." I want to--and this is just

really --Oops. I shouldn't do that.

This is really wrong. It's even in red.

And what this fails to do is make a distinction between

ultimate causation and proximate causation.

And those are technical terms referring to--Ultimate causation

is the reason why something is there in the first place,

over millions of years of history.

Proximate causation is why you're doing it now.

And these are different. Obviously, for instance,