Naomi Oreskes: Why we should trust scientists

TED
25 Jun 201419:15

Summary

TLDRThis script explores the public's skepticism towards scientific claims, such as climate change and vaccine safety, despite scientific consensus. It challenges the traditional view of the scientific method and highlights the actual practices of scientists, including inductive reasoning and modeling. The speaker emphasizes that trust in science is rooted in the collective wisdom and rigorous scrutiny of the scientific community, akin to the reliability of technology resulting from cumulative expertise.

Takeaways

  • 🌑️ Climate change and vaccine safety are topics where public trust in scientific information is crucial but often questioned.
  • πŸ€” The general public's skepticism towards scientific claims is highlighted by polls showing significant doubt about climate change, evolution, and vaccines.
  • πŸ”¬ Scientists differentiate their work from faith, emphasizing that belief is not the foundation of scientific inquiry but evidence and reason.
  • πŸ“š The scientific method, as commonly taught, is the hypothetical-deductive method, which involves forming hypotheses, deducing predictions, and testing these predictions.
  • 🌌 Einstein's theory of general relativity serves as an example of successful scientific prediction and testing, with light bending around the sun as a confirmation of his theory.
  • ❌ The textbook model of the scientific method is flawed, as it can lead to false predictions and is not the only way science is conducted.
  • πŸ” Auxiliary hypotheses, or additional assumptions scientists make, can affect the outcome of scientific tests and are a common issue in scientific practice.
  • πŸ”„ Inductive reasoning in science, as demonstrated by Charles Darwin's work, often starts with observations and data collection before forming a theory.
  • πŸ“Š Scientific models and computer simulations are tools used to understand complex phenomena like climate change and help determine causality.
  • πŸ‘₯ The consensus of scientific experts, reached through collective scrutiny and evidence evaluation, forms the basis of scientific knowledge.
  • 🧠 Trust in science is akin to trust in technology, based on the collective work and wisdom of the scientific community rather than individual genius.

Q & A

  • Why is it important to trust scientific information when making decisions about issues like climate change and vaccine safety?

    -Trusting scientific information is crucial because it provides evidence-based guidance for addressing complex issues that impact society and the environment. Scientific findings are derived from rigorous research and analysis, offering a reliable foundation for informed decision-making.

  • What is the difference between faith and science as discussed in the script?

    -Faith is based on belief without requiring empirical evidence, often associated with religious beliefs. In contrast, science is grounded in empirical evidence, testable hypotheses, and relies on the scientific method to establish facts and theories.

  • Can you explain Blaise Pascal's wager and how it relates to the discussion on faith versus science?

    -Pascal's wager is a philosophical argument that suggests it is more beneficial to believe in God's existence because the potential gains outweigh the losses. It illustrates the concept of making a leap of faith. The script contrasts this with science, which relies on evidence and reason rather than belief.

  • What is the 'textbook method' of science that the script refers to and why is it problematic?

    -The 'textbook method,' also known as the hypothetical deductive method, involves scientists developing hypotheses, deducing consequences, and testing these in the natural world. The script argues that this method is oversimplified and does not accurately represent how science is conducted, as it fails to account for the complexity and inductive reasoning often used in scientific research.

  • What is the fallacy of affirming the consequent and why does it present a problem for the textbook model of science?

    -The fallacy of affirming the consequent is a logical error where the truth of a prediction is mistakenly taken as proof of the truth of the theory that predicted it. This is problematic because even false theories can make true predictions, so successful predictions do not necessarily validate a scientific theory.

  • How do auxiliary hypotheses complicate the relationship between predictions and scientific theories?

    -Auxiliary hypotheses are additional assumptions made during scientific investigations that may not be explicitly stated. They can complicate the validation of a theory because if these assumptions are incorrect, even accurate predictions may not support the original theory as intended.

  • What is the role of inductive reasoning in scientific research, as opposed to the deductive reasoning suggested by the textbook model?

    -Inductive reasoning involves drawing general conclusions from specific observations. Unlike deductive reasoning, which goes from general premises to specific conclusions, inductive reasoning is more about forming hypotheses from patterns observed in data, as exemplified by Charles Darwin's work on natural selection.

  • Why do scientists often rely on computer simulations to understand complex phenomena like climate change?

    -Computer simulations allow scientists to model and analyze complex systems with multiple variables. They can reproduce real-world observations and test the impact of different factors, helping to identify the causes of phenomena such as climate change.

  • What does the script suggest as the ultimate determinant of scientific truth?

    -The script suggests that scientific truth is determined by the consensus of experts within the scientific community. This consensus is reached through a process of organized skepticism, where evidence is collectively scrutinized and evaluated.

  • How does the script address the concern that trusting science might be an 'appeal to authority'?

    -The script acknowledges the concern but explains that in science, the appeal to authority is not based on the authority of an individual but on the collective wisdom and work of the scientific community. This collective authority is built on evidence and shared knowledge.

  • What is the 'organized skepticism' mentioned in the script, and how does it contribute to the scientific process?

    -Organized skepticism is a term used to describe the systematic and collective approach scientists use to scrutinize and challenge each other's findings. It contributes to the scientific process by ensuring that claims are rigorously tested and verified, maintaining the integrity and reliability of scientific knowledge.

  • What is the script's final argument for why we should trust scientific findings?

    -The script argues that we should trust scientific findings because they are the result of collective work, experience, and evidence-based conclusions of the scientific community. This trust is similar to the trust we place in technology, which is also based on accumulated knowledge and experience.

Outlines

00:00

πŸ€” Trust in Science Amidst Public Skepticism

This paragraph addresses the public's skepticism towards scientific claims, such as climate change and vaccine safety, despite what scientists assert. It contrasts the reliance on scientific evidence with the concept of faith, highlighting the difference between science and religion. The speaker introduces Blaise Pascal's wager as an example of faith-based reasoning and discusses the common misconception that science operates on belief. The paragraph also touches on the idea that even scientists must rely on trust in fields outside their expertise, leading to the question of why we should trust scientific claims at all.

05:01

πŸ” The Myth of the Scientific Method

The paragraph delves into the misconceptions about the scientific method, particularly the hypothetical deductive method taught in schools. It critiques the model by explaining that successful predictions do not necessarily confirm a theory's validity, using the Ptolemaic system as an example. The speaker also discusses the practical issues with this model, such as the fallacy of affirming the consequent and the problem of auxiliary hypotheses, which are additional assumptions that may be incorrect. The paragraph further explains that many scientific endeavors do not adhere to this model, being more inductive or based on modeling rather than deduction.

10:03

🌏 Climate Change and the Power of Models

This paragraph focuses on the role of models in scientific inquiry, particularly in understanding complex phenomena like climate change. It describes how scientists use computer simulations to test various factors that could influence climate, such as air pollution, volcanic dust, solar radiation, and greenhouse gases. The speaker illustrates how these models help to identify the causes of observed warming trends, attributing them to a combination of factors, with greenhouse gases playing a significant role. The paragraph emphasizes the importance of models in demonstrating causality and the collective nature of scientific evidence.

15:03

πŸ”¬ The Authority of Scientific Consensus

The final paragraph discusses the concept of scientific consensus as the basis for what constitutes scientific knowledge. It likens science to a jury of experts who, through a process of collective scrutiny, determine the validity of claims. The speaker addresses the potential criticism of science being an 'appeal to authority' by clarifying that it is not the authority of individuals but the collective wisdom of the scientific community. The paragraph concludes by drawing a parallel between trust in science and trust in technology, both of which are based on accumulated knowledge and experience, and the importance of scientists communicating their methods and evidence effectively.

Mindmap

Keywords

πŸ’‘Climate Change

Climate change refers to long-term shifts in temperatures and weather patterns. It is a central theme in the video, emphasizing the importance of scientific consensus on its causes and effects. The script mentions that scientists widely agree that the world is warming, largely due to human activities, despite some public skepticism.

πŸ’‘Vaccines

Vaccines are biological preparations that improve immunity to specific diseases. The video discusses the public's trust in scientific claims about vaccine safety. It contrasts the scientific consensus on vaccine safety with the opinions of those who are not persuaded by this consensus.

πŸ’‘Scientific Method

The scientific method is a systematic approach to investigating and understanding the natural world. The video challenges the simplistic view of the scientific method taught in schools, highlighting that real scientific practice is more complex and involves much more than just hypothesis testing.

πŸ’‘Hypothetical Deductive Method

This term from the script refers to a traditional model of the scientific method where scientists develop hypotheses and deduce predictions that can be tested. The video points out that this model is often oversimplified and does not capture the full range of scientific inquiry.

πŸ’‘Pascal's Wager

Pascal's Wager is a philosophical argument that suggests it is more beneficial to live as if God exists, as the potential gains outweigh the losses. In the video, it is used as an analogy to contrast faith and science, illustrating the difference between believing in something without evidence (faith) and accepting scientific claims based on evidence and reasoning.

πŸ’‘Stellar Parallax

Stellar parallax is the apparent shift in the position of a star when viewed from different points in Earth's orbit. The script uses it as an example to discuss the practical problems of scientific predictions and the role of auxiliary hypotheses in scientific understanding.

πŸ’‘Inductive Reasoning

Inductive reasoning is a method of reasoning where conclusions are based on a number of observations. The video contrasts this with deductive reasoning, highlighting how scientists like Charles Darwin used inductive methods to form theories from collected data.

πŸ’‘Modeling

In the context of the video, modeling refers to the creation of theoretical or physical representations to test scientific ideas. It is used to explain complex phenomena like mountain formation and climate change, demonstrating how scientists use models to understand and predict natural processes.

πŸ’‘Consensus

Consensus in the video represents the collective agreement among scientific experts after rigorous scrutiny of evidence. It is presented as the foundation of scientific knowledge, emphasizing that trust in science is essentially a trust in the collective judgment of the scientific community.

πŸ’‘Organized Skepticism

Organized skepticism is a concept where the scientific community collectively and systematically questions and scrutinizes claims. The video describes this as a key process in science, ensuring that novel claims are rigorously tested and vetted before being accepted.

πŸ’‘Authority

The video discusses the role of authority in science, arguing that while science does involve an appeal to authority, it is not to the authority of individuals but to the collective authority of the scientific community. This collective authority is based on the accumulated knowledge and evidence gathered by scientists over time.

πŸ’‘Collective Intelligence

Collective intelligence refers to the shared knowledge and skills of a group, which in the context of the video, is central to the development of scientific understanding. The script illustrates how trust in science is a trust in the collective efforts and findings of the scientific community, much like the trust in technology is based on the accumulated work of many contributors.

Highlights

The importance of scientific information in answering everyday questions about climate change and vaccine safety.

The contrast between science and faith, emphasizing that belief is not the domain of science.

Pascal's wager as an example of applying scientific reasoning to religious belief.

The common misconception that most scientific claims require a leap of faith for both the public and scientists outside their specialties.

The explanation of why scientists accept claims from other fields despite their own limitations in expertise.

The critique of the textbook scientific method, highlighting its limitations and inaccuracies.

Einstein's theory of general relativity and its experimental confirmation as a historical example of the scientific method.

The logical flaw of affirming the consequent, showing that true predictions do not guarantee a correct theory.

The historical example of the Ptolemaic and Copernican models to illustrate the problems with the textbook model.

The concept of auxiliary hypotheses and their impact on scientific predictions and observations.

The role of inductive reasoning in science, as demonstrated by Charles Darwin's development of the theory of natural selection.

The significance of scientific modeling in understanding complex phenomena like climate change.

The explanation of how computer simulations help scientists understand the causes of observed phenomena.

The philosopher Paul Feyerabend's quote on the flexibility and creativity in scientific methods.

The concept of 'organized skepticism' as a way to scrutinize scientific evidence within the scientific community.

The idea that scientific knowledge is the consensus of experts reached through collective scrutiny.

The paradox of science as an appeal to authority based on the collective wisdom of the scientific community.

The analogy of the reliability of modern automobiles to illustrate the trust in the collective work of scientists.

The call for better communication from scientists to explain not just their findings but also their methods.

Transcripts

play00:12

Every day we face issues like climate change

play00:16

or the safety of vaccines

play00:17

where we have to answer questions whose answers

play00:20

rely heavily on scientific information.

play00:23

Scientists tell us that the world is warming.

play00:26

Scientists tell us that vaccines are safe.

play00:29

But how do we know if they are right?

play00:31

Why should be believe the science?

play00:33

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

play00:36

Public opinion polls consistently show

play00:39

that significant proportions of the American people

play00:42

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

play00:45

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

play00:48

and aren't persuaded by the safety of vaccines.

play00:52

So why should we believe the science?

play00:56

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

play00:59

In fact, they would contrast science with faith,

play01:02

and they would say belief is the domain of faith.

play01:05

And faith is a separate thing apart and distinct from science.

play01:09

Indeed they would say religion is based on faith

play01:12

or maybe the calculus of Pascal's wager.

play01:15

Blaise Pascal was a 17th-century mathematician

play01:18

who tried to bring scientific reasoning to the question of

play01:21

whether or not he should believe in God,

play01:23

and his wager went like this:

play01:25

Well, if God doesn't exist

play01:28

but I decide to believe in him

play01:30

nothing much is really lost.

play01:32

Maybe a few hours on Sunday.

play01:34

(Laughter)

play01:35

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

play01:38

then I'm in deep trouble.

play01:40

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

play01:43

Or as one of my college professors said,

play01:45

"He clutched for the handrail of faith."

play01:47

He made that leap of faith

play01:49

leaving science and rationalism behind.

play01:54

Now the fact is though, for most of us,

play01:56

most scientific claims are a leap of faith.

play02:00

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

play02:04

And indeed this is actually true for most scientists as well

play02:07

outside of their own specialties.

play02:09

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

play02:12

whether a vaccine is safe.

play02:13

Most chemists are not experts in evolutionary theory.

play02:16

A physicist cannot tell you,

play02:19

despite the claims of some of them,

play02:20

whether or not tobacco causes cancer.

play02:24

So, if even scientists themselves

play02:26

have to make a leap of faith

play02:27

outside their own fields,

play02:29

then why do they accept the claims of other scientists?

play02:33

Why do they believe each other's claims?

play02:35

And should we believe those claims?

play02:39

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

play02:41

but not for the reason that most of us think.

play02:44

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

play02:47

believe in science is because of the scientific method.

play02:50

We were taught that scientists follow a method

play02:53

and that this method guarantees

play02:55

the truth of their claims.

play02:57

The method that most of us were taught in school,

play03:01

we can call it the textbook method,

play03:02

is the hypothetical deductive method.

play03:05

According to the standard model, the textbook model,

play03:08

scientists develop hypotheses, they deduce

play03:11

the consequences of those hypotheses,

play03:14

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

play03:15

"Okay, well are those consequences true?"

play03:18

Can we observe them taking place in the natural world?

play03:21

And if they are true, then the scientists say,

play03:24

"Great, we know the hypothesis is correct."

play03:27

So there are many famous examples in the history

play03:29

of science of scientists doing exactly this.

play03:32

One of the most famous examples

play03:34

comes from the work of Albert Einstein.

play03:36

When Einstein developed the theory of general relativity,

play03:38

one of the consequences of his theory

play03:41

was that space-time wasn't just an empty void

play03:44

but that it actually had a fabric.

play03:45

And that that fabric was bent

play03:47

in the presence of massive objects like the sun.

play03:50

So if this theory were true then it meant that light

play03:53

as it passed the sun

play03:55

should actually be bent around it.

play03:57

That was a pretty startling prediction

play03:59

and it took a few years before scientists

play04:01

were able to test it

play04:03

but they did test it in 1919,

play04:05

and lo and behold it turned out to be true.

play04:07

Starlight actually does bend as it travels around the sun.

play04:11

This was a huge confirmation of the theory.

play04:13

It was considered proof of the truth

play04:15

of this radical new idea,

play04:16

and it was written up in many newspapers

play04:18

around the globe.

play04:21

Now, sometimes this theory or this model

play04:23

is referred to as the deductive-nomological model,

play04:26

mainly because academics like to make things complicated.

play04:30

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

play04:35

So nomological means having to do with laws.

play04:38

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

play04:41

ideally, it is a law of nature.

play04:43

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

play04:46

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

play04:48

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

play04:50

in all times and all places

play04:52

no matter what the circumstances are.

play04:54

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

play04:57

Einstein's famous equation, E=MC2,

play05:01

which tells us what the relationship is

play05:03

between energy and mass.

play05:05

And that relationship is true no matter what.

play05:09

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

play05:13

The main problem is that it's wrong.

play05:16

It's just not true. (Laughter)

play05:20

And I'm going to talk about three reasons why it's wrong.

play05:22

So the first reason is a logical reason.

play05:25

It's the problem of the fallacy of affirming the consequent.

play05:29

So that's another fancy, academic way of saying

play05:31

that false theories can make true predictions.

play05:34

So just because the prediction comes true

play05:36

doesn't actually logically prove that the theory is correct.

play05:39

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

play05:43

This is a picture of the Ptolemaic universe

play05:46

with the Earth at the center of the universe

play05:48

and the sun and the planets going around it.

play05:50

The Ptolemaic model was believed

play05:52

by many very smart people for many centuries.

play05:56

Well, why?

play05:57

Well the answer is because it made lots of predictions that came true.

play06:01

The Ptolemaic system enabled astronomers

play06:03

to make accurate predictions of the motions of the planet,

play06:06

in fact more accurate predictions at first

play06:08

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

play06:12

So that's one problem with the textbook model.

play06:15

A second problem is a practical problem,

play06:18

and it's the problem of auxiliary hypotheses.

play06:21

Auxiliary hypotheses are assumptions

play06:24

that scientists are making

play06:26

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

play06:29

So an important example of this

play06:31

comes from the Copernican model,

play06:33

which ultimately replaced the Ptolemaic system.

play06:37

So when Nicolaus Copernicus said,

play06:39

actually the Earth is not the center of the universe,

play06:41

the sun is the center of the solar system,

play06:43

the Earth moves around the sun.

play06:45

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

play06:48

we ought to be able to detect the motion

play06:50

of the Earth around the sun.

play06:52

And so this slide here illustrates a concept

play06:54

known as stellar parallax.

play06:56

And astronomers said, if the Earth is moving

play07:00

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

play07:03

well I know I'm in Manhattan so you guys can't see the stars,

play07:05

but imagine you're out in the country, imagine you chose that rural life β€”

play07:09

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

play07:12

against the backdrop of distant stars.

play07:15

If we now make the same observation six months later

play07:18

when the Earth has moved to this position in June,

play07:22

we look at that same star and we see it against a different backdrop.

play07:26

That difference, that angular difference, is the stellar parallax.

play07:30

So this is a prediction that the Copernican model makes.

play07:33

Astronomers looked for the stellar parallax

play07:35

and they found nothing, nothing at all.

play07:40

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

play07:44

So what happened?

play07:46

Well, in hindsight we can say that astronomers were making

play07:48

two auxiliary hypotheses, both of which

play07:51

we would now say were incorrect.

play07:53

The first was an assumption about the size of the Earth's orbit.

play07:57

Astronomers were assuming that the Earth's orbit was large

play08:00

relative to the distance to the stars.

play08:02

Today we would draw the picture more like this,

play08:05

this comes from NASA,

play08:06

and you see the Earth's orbit is actually quite small.

play08:09

In fact, it's actually much smaller even than shown here.

play08:12

The stellar parallax therefore,

play08:13

is very small and actually very hard to detect.

play08:17

And that leads to the second reason

play08:19

why the prediction didn't work,

play08:21

because scientists were also assuming

play08:23

that the telescopes they had were sensitive enough

play08:26

to detect the parallax.

play08:27

And that turned out not to be true.

play08:29

It wasn't until the 19th century

play08:32

that scientists were able to detect

play08:34

the stellar parallax.

play08:35

So, there's a third problem as well.

play08:38

The third problem is simply a factual problem,

play08:41

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

play08:43

A lot of science isn't deductive at all,

play08:46

it's actually inductive.

play08:48

And by that we mean that scientists don't necessarily

play08:50

start with theories and hypotheses,

play08:52

often they just start with observations

play08:54

of stuff going on in the world.

play08:57

And the most famous example of that is one of the most

play08:59

famous scientists who ever lived, Charles Darwin.

play09:02

When Darwin went out as a young man on the voyage of the Beagle,

play09:05

he didn't have a hypothesis, he didn't have a theory.

play09:09

He just knew that he wanted to have a career as a scientist

play09:12

and he started to collect data.

play09:14

Mainly he knew that he hated medicine

play09:17

because the sight of blood made him sick so

play09:19

he had to have an alternative career path.

play09:21

So he started collecting data.

play09:23

And he collected many things, including his famous finches.

play09:26

When he collected these finches, he threw them in a bag

play09:28

and he had no idea what they meant.

play09:31

Many years later back in London,

play09:33

Darwin looked at his data again and began

play09:35

to develop an explanation,

play09:38

and that explanation was the theory of natural selection.

play09:41

Besides inductive science,

play09:43

scientists also often participate in modeling.

play09:46

One of the things scientists want to do in life

play09:48

is to explain the causes of things.

play09:51

And how do we do that?

play09:52

Well, one way you can do it is to build a model

play09:54

that tests an idea.

play09:56

So this is a picture of Henry Cadell,

play09:58

who was a Scottish geologist in the 19th century.

play10:01

You can tell he's Scottish because he's wearing

play10:02

a deerstalker cap and Wellington boots.

play10:05

(Laughter)

play10:07

And Cadell wanted to answer the question,

play10:08

how are mountains formed?

play10:10

And one of the things he had observed

play10:12

is that if you look at mountains like the Appalachians,

play10:14

you often find that the rocks in them

play10:16

are folded,

play10:17

and they're folded in a particular way,

play10:19

which suggested to him

play10:20

that they were actually being compressed from the side.

play10:23

And this idea would later play a major role

play10:25

in discussions of continental drift.

play10:28

So he built this model, this crazy contraption

play10:30

with levers and wood, and here's his wheelbarrow,

play10:33

buckets, a big sledgehammer.

play10:35

I don't know why he's got the Wellington boots.

play10:37

Maybe it's going to rain.

play10:38

And he created this physical model in order

play10:42

to demonstrate that you could, in fact, create

play10:46

patterns in rocks, or at least, in this case, in mud,

play10:48

that looked a lot like mountains

play10:50

if you compressed them from the side.

play10:52

So it was an argument about the cause of mountains.

play10:56

Nowadays, most scientists prefer to work inside,

play10:59

so they don't build physical models so much

play11:01

as to make computer simulations.

play11:04

But a computer simulation is a kind of a model.

play11:07

It's a model that's made with mathematics,

play11:08

and like the physical models of the 19th century,

play11:12

it's very important for thinking about causes.

play11:15

So one of the big questions to do with climate change,

play11:18

we have tremendous amounts of evidence

play11:20

that the Earth is warming up.

play11:22

This slide here, the black line shows

play11:24

the measurements that scientists have taken

play11:26

for the last 150 years

play11:28

showing that the Earth's temperature

play11:30

has steadily increased,

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and you can see in particular that in the last 50 years

play11:34

there's been this dramatic increase

play11:36

of nearly one degree centigrade,

play11:38

or almost two degrees Fahrenheit.

play11:41

So what, though, is driving that change?

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How can we know what's causing

play11:45

the observed warming?

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Well, scientists can model it

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using a computer simulation.

play11:51

So this diagram illustrates a computer simulation

play11:54

that has looked at all the different factors

play11:56

that we know can influence the Earth's climate,

play11:59

so sulfate particles from air pollution,

play12:01

volcanic dust from volcanic eruptions,

play12:04

changes in solar radiation,

play12:07

and, of course, greenhouse gases.

play12:09

And they asked the question,

play12:11

what set of variables put into a model

play12:14

will reproduce what we actually see in real life?

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So here is the real life in black.

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Here's the model in this light gray,

play12:22

and the answer is

play12:23

a model that includes, it's the answer E on that SAT,

play12:28

all of the above.

play12:30

The only way you can reproduce

play12:31

the observed temperature measurements

play12:33

is with all of these things put together,

play12:35

including greenhouse gases,

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and in particular you can see that the increase

play12:40

in greenhouse gases tracks

play12:42

this very dramatic increase in temperature

play12:44

over the last 50 years.

play12:45

And so this is why climate scientists say

play12:48

it's not just that we know that climate change is happening,

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we know that greenhouse gases are a major part

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of the reason why.

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So now because there all these different things

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that scientists do,

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the philosopher Paul Feyerabend famously said,

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"The only principle in science

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that doesn't inhibit progress is: anything goes."

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Now this quotation has often been taken out of context,

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because Feyerabend was not actually saying

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that in science anything goes.

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What he was saying was,

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actually the full quotation is,

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"If you press me to say

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what is the method of science,

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I would have to say: anything goes."

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What he was trying to say

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is that scientists do a lot of different things.

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Scientists are creative.

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But then this pushes the question back:

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If scientists don't use a single method,

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then how do they decide

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what's right and what's wrong?

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And who judges?

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And the answer is, scientists judge,

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and they judge by judging evidence.

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Scientists collect evidence in many different ways,

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but however they collect it,

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they have to subject it to scrutiny.

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And this led the sociologist Robert Merton

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to focus on this question of how scientists

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scrutinize data and evidence,

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and he said they do it in a way he called

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"organized skepticism."

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And by that he meant it's organized

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because they do it collectively,

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they do it as a group,

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and skepticism, because they do it from a position

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of distrust.

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That is to say, the burden of proof

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is on the person with a novel claim.

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And in this sense, science is intrinsically conservative.

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It's quite hard to persuade the scientific community

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to say, "Yes, we know something, this is true."

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So despite the popularity of the concept

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of paradigm shifts,

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what we find is that actually,

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really major changes in scientific thinking

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are relatively rare in the history of science.

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So finally that brings us to one more idea:

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If scientists judge evidence collectively,

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this has led historians to focus on the question

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of consensus,

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and to say that at the end of the day,

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what science is,

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what scientific knowledge is,

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is the consensus of the scientific experts

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who through this process of organized scrutiny,

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collective scrutiny,

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have judged the evidence

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and come to a conclusion about it,

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either yea or nay.

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So we can think of scientific knowledge

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as a consensus of experts.

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We can also think of science as being

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a kind of a jury,

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except it's a very special kind of jury.

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It's not a jury of your peers,

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it's a jury of geeks.

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It's a jury of men and women with Ph.D.s,

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and unlike a conventional jury,

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which has only two choices,

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guilty or not guilty,

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the scientific jury actually has a number of choices.

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Scientists can say yes, something's true.

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Scientists can say no, it's false.

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Or, they can say, well it might be true

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but we need to work more and collect more evidence.

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Or, they can say it might be true,

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but we don't know how to answer the question

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and we're going to put it aside

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and maybe we'll come back to it later.

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That's what scientists call "intractable."

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But this leads us to one final problem:

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If science is what scientists say it is,

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then isn't that just an appeal to authority?

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And weren't we all taught in school

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that the appeal to authority is a logical fallacy?

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Well, here's the paradox of modern science,

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the paradox of the conclusion I think historians

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and philosophers and sociologists have come to,

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that actually science is the appeal to authority,

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but it's not the authority of the individual,

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no matter how smart that individual is,

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like Plato or Socrates or Einstein.

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It's the authority of the collective community.

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You can think of it is a kind of wisdom of the crowd,

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but a very special kind of crowd.

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Science does appeal to authority,

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but it's not based on any individual,

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no matter how smart that individual may be.

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It's based on the collective wisdom,

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the collective knowledge, the collective work,

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of all of the scientists who have worked

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on a particular problem.

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Scientists have a kind of culture of collective distrust,

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this "show me" culture,

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illustrated by this nice woman here

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showing her colleagues her evidence.

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Of course, these people don't really look like scientists,

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because they're much too happy.

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(Laughter)

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Okay, so that brings me to my final point.

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Most of us get up in the morning.

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Most of us trust our cars.

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Well, see, now I'm thinking, I'm in Manhattan,

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this is a bad analogy,

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but most Americans who don't live in Manhattan

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get up in the morning and get in their cars

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and turn on that ignition, and their cars work,

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and they work incredibly well.

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The modern automobile hardly ever breaks down.

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So why is that? Why do cars work so well?

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It's not because of the genius of Henry Ford

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or Karl Benz or even Elon Musk.

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It's because the modern automobile

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is the product of more than 100 years of work

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by hundreds and thousands

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and tens of thousands of people.

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The modern automobile is the product

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of the collected work and wisdom and experience

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of every man and woman who has ever worked

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on a car,

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and the reliability of the technology is the result

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of that accumulated effort.

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We benefit not just from the genius of Benz

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and Ford and Musk

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but from the collective intelligence and hard work

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of all of the people who have worked

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on the modern car.

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And the same is true of science,

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only science is even older.

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Our basis for trust in science is actually the same

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as our basis in trust in technology,

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and the same as our basis for trust in anything,

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namely, experience.

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But it shouldn't be blind trust

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any more than we would have blind trust in anything.

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Our trust in science, like science itself,

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should be based on evidence,

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and that means that scientists

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have to become better communicators.

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They have to explain to us not just what they know

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but how they know it,

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and it means that we have to become better listeners.

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Thank you very much.

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(Applause)

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Science TrustSkepticismScientific MethodClimate ChangeVaccine SafetyEvolution DebateExpert ConsensusPascal's WagerInductive ReasoningModelingEvidence Based