0:00:00.930,0:00:04.058
Every day we face issues like climate change

0:00:04.058,0:00:05.488
or the safety of vaccines

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where we have to answer questions whose answers

0:00:08.528,0:00:11.989
rely heavily on scientific information.

0:00:11.989,0:00:14.870
Scientists tell us that the world is warming.

0:00:14.870,0:00:17.411
Scientists tell us that vaccines are safe.

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But how do we know if they are right?

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Why should be believe the science?

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The fact is, many of us actually[br]don't believe the science.

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Public opinion polls consistently show

0:00:27.074,0:00:30.084
that significant proportions of the American people

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don't believe the climate is[br]warming due to human activities,

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don't think that there is[br]evolution by natural selection,

0:00:36.564,0:00:40.465
and aren't persuaded by the safety of vaccines.

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So why should we believe the science?

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Well, scientists don't like talking about [br]science as a matter of belief.

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In fact, they would contract science with faith,

0:00:50.294,0:00:53.260
and they would say belief is the domain of faith.

0:00:53.260,0:00:57.038
And faith is a separate thing[br]apart and distinct from science.

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Indeed they would say religion is based on faith

0:01:00.190,0:01:03.884
or maybe the calculous of Pascal's wager.

0:01:03.884,0:01:06.560
Blaise Pascal was a 17th century mathematician

0:01:06.560,0:01:09.190
who tried to bring scientific[br]reasoning to the question of

0:01:09.190,0:01:11.242
whether or not he should believe in God,

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and his wager went like this:

0:01:13.846,0:01:16.395
well, if God doesn't exist

0:01:16.395,0:01:18.420
but I decide to believe in him

0:01:18.420,0:01:20.398
nothing much is really lost.

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Maybe a few hours on Sunday.

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[Laughter]

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But if he does exist and I don't believe in him,

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then I'm in deep trouble.

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And so Pascal said, we'd better believe in God.

0:01:31.438,0:01:33.610
Or as one of my college professors said,

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"He clutched for the handmill of faith."

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He made that leap of faith

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leaving science and rationalism behind.

0:01:42.296,0:01:44.992
Now the fact is though, for most of us,

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most scientific claims are a leap of faith.

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We can't really judge scientific[br]claims for ourselves in most cases.

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And indeed this is actually[br]true for most scientists as well

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outside of their own specialties.

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So if you think about it, a geologist can't tell you

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whether a vaccine is safe.

0:02:01.951,0:02:04.951
Most chemists are not experts in evolutionary theory.

0:02:04.951,0:02:07.210
A physicist cannot tell you,

0:02:07.210,0:02:08.653
despite the claims of some of them,

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whether or not tobacco causes cancer.

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So, if even scientists themselves

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have to make a leap of faith

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outside their own fields,

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then why do they accept the[br]claims of other scientists?

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Why do they believe each other's claims?

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And should we believe those claims?

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So what I'd like to argue is yes, we should,

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but not for the reason that most of us think.

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Most of us were taught in school[br]that the reason we should

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believe in science is because of the scientific method.

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We were taught that scientists follow a method

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and that this method guarantees

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the truth of their claims.

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The method that most of us were taught in school,

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we can call it the text book method,

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is the hypothetical deductive method.

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According to the standard[br]model, the textbook model,

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scientists develop hypotheses, they deduce

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the consequences for those hypotheses,

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and then they go out into the world and they say,

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"Okay, well are those consequences true?"

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Can we observe them taking[br]place in the natural world?

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And if they are true, then the scientists say,

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"Great, we know the hypothesis is correct."

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So there are many famous examples in the history

0:03:17.183,0:03:20.062
of science of scientists doing exactly this.

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One of the most famous examples

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comes from the work of Albert Einstein.

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When Einstein developed the[br]theory of general relativity,

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one of the consequences of his theory

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was that space time wasn't just an empty void

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but that it actually had a fabric.

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And that that fabric was bent

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in the presence of massive objects like the sun.

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So if this theory were true then it meant that light

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as it passed the sun

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should actually be bent around it.

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That was a pretty startling prediction

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and it took a few years before scientists

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were able to test it

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but they did test it in 1919,

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and lo and behold it turned out to be true.

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Starlight actually does bend[br]as it travels around the sun.

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This was a huge confirmation of the theory.

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It was considered proof of the truth

0:04:03.088,0:04:05.420
of this radical new idea,

0:04:05.420,0:04:06.332
and it was written up in many newspapers

0:04:06.332,0:04:09.450
around the globe.

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Now sometimes this theory or this model

0:04:11.850,0:04:14.874
is referred to as the deductive-nomological model.

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Meaning those academics[br]like to make things complicated.

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But also because in the ideal case, it's about laws.

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So nomological means having to do with laws.

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And in the ideal case, the hypothesis isn't just an idea:

0:04:29.135,0:04:31.321
ideally, it is a law of nature.

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Why does it matter that it is a law of nature?

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Because if it is a law, it can't be broken.

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If it's a law then it will always be true

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in all times and all places

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no matter what the circumstances are.

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And all of you know at least[br]one example of a famous law:

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Einstein's famous equation, E=MC2,

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which tells us what the relationship is

0:04:50.778,0:04:53.161
between energy and mass.

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And that relationship is true no matter what.

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Now, it turns out though that there are [br]several problems with this model.

0:05:01.240,0:05:03.985
The main problem is that it's wrong.

0:05:03.985,0:05:07.947
It's just not true. (Laughter)

0:05:07.947,0:05:10.870
And I'm going to talk about[br]three reasons why it's wrong.

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So the first reason is a logical reason.

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It's the problem of the fallacy[br]of affirming the consequent.

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So that's another fancy academic way of saying

0:05:19.391,0:05:22.471
that false theories can make true predictions.

0:05:22.471,0:05:24.115
So just because the prediction comes true

0:05:24.115,0:05:27.477
doesn't actually logically[br]prove that the theory is correct.

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And I have a good example of that too, [br]again from the history of science.

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This is a picture of the Ptolemaic universe

0:05:33.993,0:05:36.265
with the Earth at the center of the universe

0:05:36.265,0:05:38.320
and the sun and the planets going around it.

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The Ptolemaic model was believed

0:05:41.240,0:05:43.903
by many very smart people for many centuries.

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Well, why?

0:05:45.589,0:05:48.946
Well the answer is because it made [br]lots of predictions that came true.

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The Ptolemaic system enabled astronomers

0:05:51.002,0:05:53.812
to make accurate predictions[br]of the motions of the planet,

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in fact more accurate predictions at first

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than the Copernican theory[br]which we now would say is true.

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So that's one problem with the textbook model.

0:06:03.347,0:06:05.763
A second problem is a practical problem,

0:06:05.763,0:06:08.948
and it's the problem of auxiliary hypotheses.

0:06:08.948,0:06:11.967
Auxiliary hypotheses are assumptions

0:06:11.967,0:06:13.836
that scientists are making

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that they may or may not even[br]be aware that they're making.

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So an important example of this

0:06:19.490,0:06:21.945
comes from the Copernican model,

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which ultimately replaced the Ptolemaic system.

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So when Nicolaus Copernicus said,

0:06:26.687,0:06:29.247
actually the Earth is not the center of the universe,

0:06:29.247,0:06:31.565
the sun is the center of the solar system,

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the Earth moves around the sun.

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Scientists said, well okay, Nicolaus, if that's true

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we ought to be able to detect the motion

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of the Earth around the sun.

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And so this slide here illustrates a concept

0:06:42.403,0:06:44.211
known as stellar parallax.

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And astronomers said, if the Earth is moving

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and we look at a prominent star, let's say, Sirius

0:06:51.243,0:06:53.357
—well I know I'm in Manhattan[br]so you guys can't see the stars,

0:06:53.357,0:06:56.748
but imagine you're out in the country, [br]imagine you chose that rural life—

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and we look at a star in December, we see that star

0:06:59.885,0:07:03.240
against the backdrop of distant stars.

0:07:03.240,0:07:05.954
If we now make the same observation six months later

0:07:05.954,0:07:09.456
when the Earth has moved to this position in June,

0:07:09.456,0:07:13.815
we look at that same star and we see it against a different backdrop.

0:07:13.815,0:07:18.287
That difference, that angular[br]difference, is the stellar parallax.

0:07:18.287,0:07:20.790
So this is the prediction that[br]the Copernican model makes.

0:07:20.790,0:07:23.071
Astronomers looked for the stellar parallax

0:07:23.071,0:07:28.693
and they found nothing, nothing at all.

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And many people argued that this proved [br]that the Copernican model was false.

0:07:32.319,0:07:34.047
So what happened?

0:07:34.047,0:07:36.730
Well in hindsight we can say that astronomers were making

0:07:36.730,0:07:38.777
two auxiliary hypotheses, both of which

0:07:38.777,0:07:42.120
we would now say were incorrect.

0:07:42.120,0:07:45.085
The first was an assumption about the size of the Earth's orbit.

0:07:45.085,0:07:48.251
Astronomers were assuming that the Earth's orbit was large

0:07:48.251,0:07:50.629
relative to the distance of the stars.

0:07:50.629,0:07:53.113
Today we would draw the picture more like this,

0:07:53.113,0:07:54.760
this comes from NASA,

0:07:54.760,0:07:57.183
and you see the Earth's orbit is actually quite small.

0:07:57.183,0:08:00.174
In fact, it's actually much[br]smaller even than shown here.

0:08:00.174,0:08:01.483
The stellar parallax therefore,

0:08:01.483,0:08:04.937
is very small and actually very hard to detect.

0:08:04.937,0:08:07.011
And that leads to the second reason

0:08:07.011,0:08:09.560
why the prediction didn't work,

0:08:09.560,0:08:11.045
because scientists were also assuming

0:08:11.045,0:08:13.945
that the telescopes they had were sensitive enough

0:08:13.945,0:08:15.955
to detect the parallax.

0:08:15.955,0:08:17.972
And that turned out not to be true.

0:08:17.972,0:08:20.036
It wasn't until the 19th century

0:08:20.036,0:08:21.860
that scientists were able to detect

0:08:21.860,0:08:23.726
the stellar parallax.

0:08:23.726,0:08:26.372
So, there's a third problem as well.

0:08:26.372,0:08:29.150
The third problem is simply a factual problem,

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that a lot of science doesn't fit the textbook model.

0:08:31.586,0:08:33.959
A lot of science isn't deductive at all,

0:08:33.959,0:08:35.537
it's actually inductive.

0:08:35.537,0:08:38.123
And by that we mean that scientists don't necessarily

0:08:38.123,0:08:40.754
start with theories and hypotheses, often they just

0:08:40.754,0:08:44.633
start with observations of stuff going on in the world.

0:08:44.633,0:08:47.172
And the most famous example[br]of that is one of the most

0:08:47.172,0:08:50.247
famous scientists who ever lived, Charles Darwin.

0:08:50.247,0:08:53.349
When Darwin went out as a young [br]man on the voyage of the Beagle,

0:08:53.349,0:08:57.101
he didn't have a hypothesis, he didn't have a theory.

0:08:57.101,0:09:00.217
He just knew that he wanted[br]to have a career as a scientist

0:09:00.217,0:09:02.179
and he started to collect data.

0:09:02.179,0:09:04.279
Mainly he knew that he hated medicine

0:09:04.279,0:09:06.557
because the sight of blood made him sick so

0:09:06.557,0:09:09.015
he had to have an alternative career path.

0:09:09.015,0:09:11.029
So he started collecting data.

0:09:11.029,0:09:14.235
And he collected many things including his famous finches.

0:09:14.235,0:09:16.615
When he collected these finches,[br]he threw them in a bag

0:09:16.615,0:09:19.185
and he had no idea what they meant.

0:09:19.185,0:09:21.102
Many years later back in London,

0:09:21.102,0:09:23.305
Darwin looked at his data again and began

0:09:23.305,0:09:25.743
to develop an explanation,

0:09:25.743,0:09:29.091
and that explanation was the[br]theory of natural selection.

0:09:29.091,0:09:31.010
Besides inductive science,

0:09:31.010,0:09:34.146
scientists also often participate in modeling.

0:09:34.146,0:09:36.392
One of the things scientists want to do in life

0:09:36.392,0:09:39.050
is to explain the causes of things.

0:09:39.050,0:09:40.568
And how do we do that?

0:09:40.568,0:09:43.340
Well, one way you can do it is to build a model

0:09:43.340,0:09:44.872
that tests an idea.

0:09:44.872,0:09:46.373
So this is a picture of Henry Cadell,

0:09:46.373,0:09:48.889
who was a Scottish geologist in the 19th century.

0:09:48.889,0:09:50.632
You can tell he's Scottish because he's wearing

0:09:50.632,0:09:53.180
a deerstalker cap and Wellington boots.

0:09:53.180,0:09:54.984
[Laughter]

0:09:54.984,0:09:57.230
And Cadell wanted to answer the question,

0:09:57.230,0:09:58.408
how are mountains formed?

0:09:58.408,0:09:59.944
And one of the things he had observed

0:09:59.944,0:10:02.298
is that if you look at mountains[br]like the Appalachians,

0:10:02.298,0:10:04.321
you often find that the rocks in them

0:10:04.321,0:10:06.280
are folded,

0:10:06.280,0:10:07.246
and they're folded in a particular way,

0:10:07.246,0:10:08.950
which suggested to him

0:10:08.950,0:10:11.499
that they were actually being[br]compressed from the side.

0:10:11.499,0:10:13.737
And this idea would later play a major role

0:10:13.737,0:10:16.090
in discussions of continental drift.

0:10:16.090,0:10:18.576
So he built this model, this crazy contraption

0:10:18.576,0:10:20.818
with levers and wood and here's his wheelbarrow,

0:10:20.818,0:10:23.090
buckets, a big sledgehammer.

0:10:23.090,0:10:25.028
I don't know why he's got the Wellington boots.

0:10:25.028,0:10:26.765
Maybe it's going to rain.

0:10:26.765,0:10:29.810
And he created this physical model in order

0:10:29.810,0:10:34.095
to demonstrate that you could in fact create

0:10:34.095,0:10:36.489
patterns in rocks, or at least in this case in mud,

0:10:36.489,0:10:38.935
that looked a lot like mountains

0:10:38.935,0:10:40.777
if you compressed them from the side.

0:10:40.777,0:10:43.905
So it was an argument about[br]the cause of mountains.

0:10:43.905,0:10:46.703
Nowadays, most scientists prefer to work inside,

0:10:46.703,0:10:50.020
so they don't build physical models so much

0:10:50.020,0:10:51.671
as to make computer simulations.

0:10:51.671,0:10:55.270
But a computer simulation is a kind of a model.

0:10:55.270,0:10:56.943
It's a model that's made with mathematics,

0:10:56.943,0:10:59.116
and like the physical models of the 19th century,

0:10:59.116,0:11:03.524
it's very important for thinking about causes.

0:11:03.524,0:11:05.989
So one of the big questions[br]to do with climate change,

0:11:05.989,0:11:08.372
we have tremendous amounts of evidence

0:11:08.372,0:11:09.902
that the earth is warming up.

0:11:09.902,0:11:12.126
This slide here, the black line shows

0:11:12.126,0:11:14.276
the measurements that scientists have taken

0:11:14.276,0:11:16.529
for the last 150 years

0:11:16.529,0:11:17.949
showing that the earth's temperature

0:11:17.949,0:11:19.513
has steadily increased,

0:11:19.513,0:11:21.989
and you can see in particular[br]that in the last 50 years

0:11:21.989,0:11:24.203
there's been this dramatic increase

0:11:24.203,0:11:26.513
of nearly one degree Centigrade,

0:11:26.513,0:11:28.748
or almost two degrees Fahrenheit.

0:11:28.748,0:11:31.605
So what, though, is driving that change?

0:11:31.605,0:11:33.940
How can we know what's causing

0:11:33.940,0:11:35.436
the observed warming?

0:11:35.436,0:11:36.880
Well, scientists can model it

0:11:36.880,0:11:39.048
using a computer simulation.

0:11:39.048,0:11:41.830
So this diagram illustrates a computer simulation

0:11:41.830,0:11:44.151
that has looked at all the different factors

0:11:44.151,0:11:46.436
that we know can influence the earth's climate,

0:11:46.436,0:11:49.338
so sulfate particles from air pollution,

0:11:49.338,0:11:52.778
volcanic dust from volcanic eruptions,

0:11:52.778,0:11:54.332
changes in solar radiation,

0:11:54.332,0:11:56.980
and, of course, greenhouse gases.

0:11:56.980,0:11:58.748
And they asked the question,

0:11:58.748,0:12:01.904
what set of variables put into a model

0:12:01.904,0:12:06.250
will reproduce what we actually see in real life?

0:12:06.250,0:12:07.900
So here is the real life in black.

0:12:07.900,0:12:09.900
Here's the model in this light grey,

0:12:09.900,0:12:11.740
and the answer is

0:12:11.740,0:12:15.867
a model that includes, it's the answer E on that SAT,

0:12:15.867,0:12:18.268
all of the above.

0:12:18.268,0:12:19.884
The only way you can reproduce

0:12:19.884,0:12:21.422
the observed temperature measurements

0:12:21.422,0:12:23.580
is with all of these things put together,

0:12:23.580,0:12:25.539
including greenhouse gases,

0:12:25.539,0:12:28.270
and in particular you can see that the increase

0:12:28.270,0:12:29.774
in greenhouse gases tracks

0:12:29.774,0:12:32.380
this very dramatic increase in temperature

0:12:32.380,0:12:33.700
over the last 50 years.

0:12:33.700,0:12:36.124
And so this is why climate scientists say

0:12:36.124,0:12:38.942
it's not just that we know that[br]climate change is happening,

0:12:38.942,0:12:41.870
we know that greenhouse gases are a major part

0:12:41.870,0:12:45.350
of the reason why.

0:12:45.350,0:12:46.668
So now because there all these different things

0:12:46.668,0:12:48.487
that scientists do,

0:12:48.487,0:12:50.933
the philosopher Paul Feyerabend famously said,

0:12:50.933,0:12:53.389
"The only principle in science

0:12:53.389,0:12:57.658
that doesn't inhibit progress is: anything goes."

0:12:57.658,0:13:00.464
Now this quotation has often[br]been taken out of context,

0:13:00.464,0:13:02.582
because Feyerabend was not actually saying

0:13:02.582,0:13:03.962
that in science anything goes.

0:13:03.962,0:13:05.876
What he was saying was,

0:13:05.876,0:13:07.900
actually the full quotation is,

0:13:07.900,0:13:09.990
"If you press me to say

0:13:09.990,0:13:11.636
what is the method of science,

0:13:11.636,0:13:15.265
I would have to say: anything goes."

0:13:15.265,0:13:16.523
What he was trying to say

0:13:16.523,0:13:19.110
is that scientists do a lot of different things.

0:13:19.110,0:13:21.218
Scientists are creative.

0:13:21.218,0:13:23.328
But then this pushes the question back:

0:13:23.328,0:13:26.389
if scientists don't use a single method,

0:13:26.389,0:13:28.418
then how do they decide

0:13:28.418,0:13:30.156
what's right and what's wrong?

0:13:30.156,0:13:32.730
And who judges?

0:13:32.730,0:13:34.530
And the answer is, scientists judge,

0:13:34.530,0:13:37.013
and they judge by judging evidence.

0:13:37.013,0:13:39.942
Scientists collect evidence in many different ways,

0:13:39.942,0:13:42.044
but however they collect it,

0:13:42.044,0:13:44.621
they have to subject it to scrutiny.

0:13:44.621,0:13:46.891
And this led to sociologist Robert Merton

0:13:46.891,0:13:49.361
to focus on this question of how scientists

0:13:49.361,0:13:51.280
scrutinize data and evidence,

0:13:51.280,0:13:53.418
and he said they do it in a way he called

0:13:53.418,0:13:55.767
"organized skepticism."

0:13:55.767,0:13:57.651
And by that he meant it's organized

0:13:57.651,0:13:59.129
because they do it collectively,

0:13:59.129,0:14:00.908
they do it as a group,

0:14:00.908,0:14:03.574
and skepticism, because they do it from a position

0:14:03.574,0:14:05.028
of distrust.

0:14:05.028,0:14:07.180
That is to say, the burden of proof

0:14:07.180,0:14:09.471
is on the person with a novel claim.

0:14:09.471,0:14:12.614
And in this sense, science[br]is intrinsically conservative.

0:14:12.614,0:14:15.186
It's quite hard to persuade the scientific community

0:14:15.186,0:14:18.897
to say, "Yes, we know something, this is true."

0:14:18.897,0:14:21.173
So despite the popularity of the concept

0:14:21.173,0:14:22.990
of paradigm shifts,

0:14:22.990,0:14:24.274
what we find is that actually,

0:14:24.274,0:14:26.479
really major changes in scientific thinking

0:14:26.479,0:14:30.779
are relatively rare in the history of science.

0:14:30.779,0:14:34.342
So finally that brings us to one more idea:

0:14:34.342,0:14:38.050
if scientists judge evidence collectively,

0:14:38.050,0:14:40.382
this has led historians to focus on the question

0:14:40.382,0:14:42.031
of consensus,

0:14:42.031,0:14:43.926
and to say that at the end of the day,

0:14:43.926,0:14:46.400
what science is,

0:14:46.400,0:14:47.530
what scientific knowledge is,

0:14:47.530,0:14:50.679
is the consensus of the scientific experts

0:14:50.679,0:14:53.063
who through this process of organized scrutiny,

0:14:53.063,0:14:54.888
collective scrutiny,

0:14:54.888,0:14:56.610
have judged the evidence

0:14:56.610,0:14:59.207
and come to a conclusion about it,

0:14:59.207,0:15:01.884
either yea or nay.

0:15:01.884,0:15:03.608
So we can think of scientific knowledge

0:15:03.608,0:15:05.480
as a consensus of experts.

0:15:05.480,0:15:07.012
We can also think of science as being

0:15:07.012,0:15:09.010
a kind of a jury,

0:15:09.010,0:15:11.184
except it's a very special kind of jury.

0:15:11.184,0:15:13.368
It's not a jury of your peers,

0:15:13.368,0:15:15.804
it's a jury of geeks.

0:15:15.804,0:15:18.928
It's a jury of men and women with Ph.Ds,

0:15:18.928,0:15:20.830
and unlike a conventional jury,

0:15:20.830,0:15:23.290
which has only two choices,

0:15:23.290,0:15:25.445
guilty or not guilty,

0:15:25.445,0:15:28.926
the scientific jury actually has a number of choices.

0:15:28.926,0:15:32.680
Scientists can say yes, something's true.

0:15:32.680,0:15:35.500
Scientists can say no, it's false.

0:15:35.500,0:15:36.920
Or, they can say, well it might be true

0:15:36.920,0:15:39.984
but we need to work more[br]and collect more evidence.

0:15:39.984,0:15:41.940
Or, they can say it might be true,

0:15:41.940,0:15:43.250
but we don't know how to answer the question

0:15:43.250,0:15:44.950
and we're going to put it aside

0:15:44.950,0:15:47.483
and maybe we'll come back to it later.

0:15:47.483,0:15:51.425
That's what scientists call "intractable."

0:15:51.425,0:15:54.481
But this leads us to one final problem:

0:15:54.481,0:15:56.819
if science is what scientists say it is,

0:15:56.819,0:15:59.960
then isn't that just an appeal to authority?

0:15:59.960,0:16:01.022
And weren't we all taught in school

0:16:01.022,0:16:03.799
that the appeal to authority is a logical fallacy?

0:16:03.799,0:16:06.861
Well, here's the paradox of modern science,

0:16:06.861,0:16:09.193
the paradox of the conclusions I think historians

0:16:09.193,0:16:11.724
and philosophers and sociologists have come to,

0:16:11.724,0:16:15.235
that actually science is the appeal to authority,

0:16:15.235,0:16:19.051
but it's not the authority of the individual,

0:16:19.051,0:16:21.180
no matter how smart that individual is,

0:16:21.180,0:16:25.165
like Plato or Socrates or Einstein.

0:16:25.165,0:16:28.039
It's the authority of the collective community.

0:16:28.039,0:16:31.225
You can think of it is a kind of wisdom of the crowd,

0:16:31.225,0:16:35.081
but a very special kind of crowd.

0:16:35.081,0:16:36.951
Science does appeal to authority,

0:16:36.951,0:16:39.681
but it's not based on any individual,

0:16:39.681,0:16:42.127
no matter how smart that individual may be.

0:16:42.127,0:16:44.018
It's based on the collective wisdom,

0:16:44.018,0:16:46.840
the collective knowledge, the collective work,

0:16:46.840,0:16:48.078
of all of the scientists who have worked

0:16:48.078,0:16:50.855
on a particular problem.

0:16:50.855,0:16:54.021
Scientists have a kind of culture of collective distrust,

0:16:54.021,0:16:55.991
this "show me" culture,

0:16:55.991,0:16:57.931
illustrated by this nice woman here

0:16:57.931,0:17:00.923
showing her colleagues her evidence.

0:17:00.923,0:17:02.980
Of course, these people don't[br]really look like scientists,

0:17:02.980,0:17:05.326
because they're much too happy.

0:17:05.326,0:17:09.058
(Laughter)

0:17:09.058,0:17:13.050
Okay, so that brings me to my final point.

0:17:13.050,0:17:15.768
Most of us get up in the morning.

0:17:15.768,0:17:17.718
Most of us trust our cars.

0:17:17.718,0:17:19.060
Well, see, now I'm thinking, I'm in Manhattan,

0:17:19.060,0:17:20.558
this is a bad analogy,

0:17:20.558,0:17:23.102
but most Americans who don't live in Manhattan

0:17:23.102,0:17:25.400
get up in the morning and get in their cars

0:17:25.400,0:17:27.189
and turn on that ignition, and their cars work,

0:17:27.189,0:17:29.170
and they work incredibly well.

0:17:29.170,0:17:32.065
The modern automobile hardly ever breaks down.

0:17:32.065,0:17:35.148
So why is that? Why do cars work so well?

0:17:35.148,0:17:36.712
It's not because of the genius of Henry Ford

0:17:36.712,0:17:40.743
or Carl Benz or even Elon Musk.

0:17:40.743,0:17:42.465
It's because the modern automobile

0:17:42.465,0:17:47.369
is the product of more than 100 years of work

0:17:47.369,0:17:49.079
by hundreds and thousands

0:17:49.079,0:17:50.765
and tens of thousands of people.

0:17:50.765,0:17:52.626
The modern automobile is the product

0:17:52.626,0:17:55.225
of the collected work and wisdom and experience

0:17:55.225,0:17:57.812
of every man and woman who has ever worked

0:17:57.812,0:17:59.700
on a car,

0:17:59.700,0:18:02.225
and the reliability of the technology is the result

0:18:02.225,0:18:05.018
of that accumulated effort.

0:18:05.018,0:18:07.585
We benefit not just from the genius of Benz

0:18:07.585,0:18:09.221
and Ford and Musk

0:18:09.221,0:18:11.729
but from the collective intelligence and hard work

0:18:11.729,0:18:14.240
of all of the people who have worked

0:18:14.240,0:18:15.910
on the modern car.

0:18:15.910,0:18:17.660
And the same is true of science,

0:18:17.660,0:18:20.164
only science is even older.

0:18:20.164,0:18:23.068
Our basis for trust in science is actually the same

0:18:23.068,0:18:25.372
as our basis in trust in technology,

0:18:25.372,0:18:29.459
and the same as our basis for trust in anything,

0:18:29.459,0:18:32.047
namely, experience.

0:18:32.047,0:18:33.961
But it shouldn't be blind trust

0:18:33.961,0:18:36.921
any more than we would have blind trust in anything.

0:18:36.921,0:18:39.062
Our trust in science, like science itself,

0:18:39.062,0:18:41.185
should be based on evidence,

0:18:41.185,0:18:42.667
and that means that scientists

0:18:42.667,0:18:44.545
have to become better communicators.

0:18:44.545,0:18:47.572
They have to explain to us not just what they know

0:18:47.572,0:18:49.840
but how they know it,

0:18:49.840,0:18:53.180
and it means that we have[br]to become better listeners.

0:18:53.180,0:18:55.149
Thank you very much.

0:18:55.149,0:18:57.452
(Applause)