DARWIN PRODUCED A
MAJOR REVOLUTION
IN OUR WHOLE WAY OF THINKING.
JUST TO ORGANIZE
IT A LITTLE BIT,
I'LL MENTION THREE DIFFERENT
FEATURES OF IT THAT SEEM TO ME
CRUCIAL.
ONE-- AND THIS IS THE MOST
OBVIOUS THING TO OUR ANCESTORS,
BUT IN A WAY IT'S NOT
THE MOST IMPORTANT.
BUT IT WAS CERTAINLY THE
MOST IMPORTANT TO THEM.
AND THAT IS IT REMOVED THE
APPEARANCE OF A DIVINE HAND
IN THE CONSTRUCTION OF NATURE.
NATURE JUST LOOKS
TOO WELL ORGANIZED
TO HAVE OCCURRED AT RANDOM.
REMEMBER WHAT LEIBNITZ
SAID ABOUT THE WATCH.
IF YOU FIND A WATCH,
YOU ASSUME THERE
MUST HAVE BEEN A WATCHMAKER.
WELL, WE'RE ALL WATCHES.
I MEAN, WE ALL SEEM TO
HAVE THIS WONDERFUL DESIGN.
THINK OF OUR EYEBALL
OR OUR EAR OR JUST
THE WHOLE HUMAN
ORGANISM OR ANIMALS.
THEY ALL LOOK TO BE
BEAUTIFULLY DESIGNED.
SO THERE IS AN
APPEARANCE IN NATURE
OF THE HAND OF A DESIGNER.
AND THE AMAZING
THING ABOUT DARWIN,
TO OUR GRANDPARENTS
AT LEAST, WAS
THAT HE REMOVED THE DESIGNER.
NATURE HAS A MECHANISM OF
NATURAL SELECTION FOR PRODUCING
SOMETHING THAT
HAS THE APPEARANCE
OF AN INTELLIGENT
DESIGN, BUT IS NOT
THE RESULT OF AN
INTELLIGENT DESIGNER.
OK, THAT'S THE FIRST
THING THAT DARWIN DID.
THAT WAS MOST OBVIOUS TO
OUR GREAT-GRANDPARENTS,
AND THAT WAS A
STUNNING ACHIEVEMENT.
AND IN FACT, IT MADE A
TREMENDOUS DIFFERENCE
THROUGHOUT CULTURE.
I MEAN, JUST AN OBVIOUS
THING, IN ENGLAND
WHAT THEY FOUND IS
THAT THE PERCENTAGE
OF INTELLIGENT YOUNG MEN
GOING INTO THE MINISTRY
DECLINED DRAMATICALLY
AFTER DARWIN.
YOU JUST DIDN'T GET
SO MANY SMART PEOPLE
BECOMING COUNTRY PREACHERS.
OK.
BUT NOW THE SECOND
THING, I THINK
WAS A MUCH GREATER REVOLUTION
THAN THAT FIRST THING,
AND THAT'S STILL WITH US.
WE BEGIN TO SEE HUMAN
BEINGS AS CONTINUOUS
WITH THE REST OF NATURE.
WE BEGIN TO SEE OURSELVES AS
PART OF THE NATURAL ORDER.
NOW, PRIOR TO DARWIN AND
INDEED IN OUR WHOLE TRADITION,
IS ENMITY TOWARD THAT.
I MEAN, THE WHOLE DEFINITION
OF MAN AS THE RATIONAL ANIMAL,
AS HOMO SAPIENS, IS PART
OF THE REJECTION OF US
AS SOMEHOW JUST PART OF
NATURE, AS CONTINUOUS
WITH THE REST OF THE
ANIMAL AND PLANT KINGDOM.
WE'RE JUST A PART OF BIOLOGY.
AND THERE IS A GREAT DEAL
OF RESISTANCE TO THAT.
AND INDEED IN MY
LIFETIME THERE'S
BEEN A LOT OF
RESISTANCE TO THAT.
SO FOR EXAMPLE, WHEN I WAS AN
UNDERGRADUATE, EVEN IN BIOLOGY
COURSES WE WERE TAUGHT HUMAN
BEINGS HAVE NO INSTINCTS.
WELL, THAT'S SILLY
IF YOU THINK AT IT.
IT'S ABSOLUTELY CRAZY.
WE'VE GOT ALL
KINDS OF INSTINCTS.
BUT THAT WAS PART
OF THE RESISTANCE
TO ACCEPTING THE IDEA
THAT HUMAN BEINGS ARE
PART OF THE NATURAL ORDER.
NOW, THERE'S A THIRD FEATURE
TO THE DARWINIAN REVOLUTION
THAT I ALSO WANT TO REMARK ON.
AND THAT IS DARWIN GAVE US
A NEW MODEL OF EXPLANATION.
SO TYPICALLY IN
SCIENCE, WHAT WE DO
IS WE GET A NEW EXPLANATION BUT
NOT A NEW STYLE OF EXPLANATION,
A NEW FORM OF EXPLANATION.
AND DARWIN DID GIVE US A
NEW FORM OF EXPLANATION.
NOW, WHAT HE DID WAS GIVE US
TWO LEVELS OF EXPLANATION,
AND IT'S QUITE INTERESTING
INTELLECTUALLY.
PRIOR TO DARWIN, YOU WOULD
HAVE SAID, FOR EXAMPLE,
THE FISH HAS THE SHAPE
THAT IT HAS IN ORDER
TO ENABLE IT TO SWIM IN WATER.
BUT WHAT WE NOW SAY
IS, LOOK, THERE'S
A MECHANICAL EXPLANATION.
THERE'S A GENETIC,
A DNA EXPLANATION
OF WHY THE FISH HAS THAT SHAPE.
BUT-- AND NOW THIS IS THE
SECOND LEVEL OF EXPLANATION--
FISH THAT HAVE THAT SHAPE ARE
MORE LIKELY TO SURVIVE IN WATER
THAN FISH THAT DON'T.
A FISH THAT'S THE
SHAPE OF A BRICK
ISN'T GOING TO DO
AS WELL IN WATER
AS A FISH THAT HAS
A FISHY SHAPE TO IT.
SO SURVIVAL STILL FUNCTIONS
IN THE EXPLANATION,
BUT WE'VE REVERSED
THE CONDITIONAL.
INSTEAD OF SAYING THE FISH HAS
THIS SHAPE IN ORDER TO SURVIVE,
WE SAY, NO, THE
FISH HAS THAT SHAPE
BECAUSE IT'S GOING
TO HAVE THAT SHAPE.
BUT-- AND NOW THIS
IS THE SECOND LEVEL--
FISH THAT HAVE THAT SHAPE ARE
MORE LIKELY TO SURVIVE THAT
FISH THAT DON'T.
SO SURVIVAL STILL FUNCTIONS
AS PART OF THE EXPLANATION,
BUT IT'S NOT THE GOAL TOWARD
WHICH THE FISH IS STRIVING.
IT'S JUST SOMETHING
THAT HAPPENS.
IT'S JUST WHAT HAPPENS
THAT ENABLES THE FISH
TO REPRODUCE MORE
GENERATIONS OF FISH.
AND THAT REALLY TO ME IS ONE
OF THE MOST INTERESTING THINGS
IN THE DARWINIAN REVOLUTION.
WE SUBSTITUTED TWO
LEVELS OF EXPLANATION
FOR THE ONE LEVEL OF PURPOSEFUL
OR TELEOLOGICAL EXPLANATION.
WE'VE GOT THESE TWO
LEVELS, THE CAUSAL LEVEL--
FISH HAS THIS BECAUSE IT'S
GOT A CAUSAL MECHANISM--
AND THE FUNCTIONAL LEVEL--
ANIMALS OR ORGANISMS THAT HAVE
THIS PARTICULAR TRAIT, THE
FISH THAT HAVE THIS PARTICULAR
PHENOTYPICAL TRAIT, THEY
GOT THAT KIND OF SHAPE,
THEY'RE GOING TO SURVIVE IN
WATER AND OTHER KINDS OF BEASTS
AREN'T.
