Karl Popper, Science, & Pseudoscience: Crash Course Philosophy #8

Summary

This Crash Course Philosophy episode explores Karl Popper's influential ideas on science and knowledge. Popper distinguished between science and pseudoscience, advocating for theories that are testable and falsifiable. He emphasized the importance of seeking to disprove rather than confirm theories, and the value of revising beliefs in light of new evidence. The episode uses the example of Santa Claus to illustrate Popper's concept of falsification, highlighting the pursuit of truth through open-minded skepticism.

Takeaways

• 🌟 Karl Popper was an Austrian-British philosopher who made significant contributions to the philosophy of science, distinguishing between science and pseudoscience.
• 🔍 Popper observed that while Freud's psychoanalytic theories could seemingly explain any data point, Einstein's theory of relativity made risky predictions that could be disproven.
• 🚫 Popper critiqued Freud's method as pseudoscientific because it could always find confirmation for its theories without being open to disproof.
• 🌌 Einstein's approach was scientific according to Popper because it involved making predictions that could be falsified, as demonstrated by the 1919 solar eclipse experiment.
• 🔮 The traditional scientific method, as Popper noted, was based on observation and hypothesis formation without preconceived notions, which Popper argued was not entirely accurate.
• 🤔 Popper believed that everyone starts with a hunch or preconceived notion, influencing what they choose to observe and how they interpret it.
• 💡 Popper's key insight was that science should aim to falsify theories rather than confirm them, emphasizing the importance of testable, refutable hypotheses.
• 🎯 Confirmation of a theory should come from risky predictions that, if wrong, would disprove the theory, which Popper saw as a hallmark of good scientific theories.
• 🚫 Popper argued against irrefutable theories, stating that if a theory cannot be tested or falsified, it holds little scientific value.
• 🔄 Knowledge, according to Popper, is about probability and revising beliefs in light of new evidence, rather than seeking absolute certainty.
• 🔑 Popper's philosophy emphasizes the importance of being open to the possibility that our beliefs may be wrong, as this openness is crucial for getting closer to the truth.

Q & A

Who is the sponsor of Crash Course Philosophy?

The sponsor of Crash Course Philosophy is Squarespace.

What notable historical figures were mentioned in the script?

The script mentions Albert Einstein, Sigmund Freud, and Karl Popper.

What key distinction did Karl Popper make between types of scientific work?

Karl Popper distinguished between science and pseudo-science.

How did Karl Popper view the predictions made by Einstein and Freud?

Popper observed that Einstein made risky predictions that could disprove his theories, whereas Freud's predictions could always be explained in a way that confirmed his theories.

What was Popper's perspective on preconceived notions in scientific observation?

Popper argued that everyone has preconceived notions and that these influence what we observe and how we interpret data.

According to Popper, what is the difference between confirmation and falsification in scientific theories?

Popper believed that science aims to disconfirm theories through falsification, while pseudo-science seeks to confirm theories.

What example does the script use to explain the concept of confirmation bias?

The script uses the existence of Santa Claus as an example, explaining that if you look for evidence to confirm Santa's existence, you will find it, but this does not make it true.

What is the significance of risky predictions in scientific theories, according to Popper?

Risky predictions are significant because they can potentially disprove a theory, thus making it a genuine test of the theory's validity.

How does Popper's view on knowledge and certainty differ from Descartes' view?

Popper believed that certainty is not possible and that we should always be open to revising our beliefs based on new evidence, whereas Descartes sought absolute certainty.

What lesson about belief and evidence does the script emphasize based on Popper's philosophy?

The script emphasizes that we should only believe things for which we have reasons and be willing to let go of beliefs when they are disproven by evidence.

Outlines

00:00

🔬 The Distinguishing Features of Science and Pseudoscience

This paragraph explores the early 20th-century scientific landscape, highlighting the contributions of Einstein and Freud, and introduces Karl Popper's philosophical inquiries into the nature of scientific knowledge. Popper, influenced by the scientific methods of Einstein and Freud, developed a criterion to differentiate between science and pseudoscience. He emphasized the importance of falsifiability in scientific theories, using Einstein's general theory of relativity and Freud's psychoanalysis as contrasting examples. Popper critiqued Freud's method for being able to explain any data point, thus lacking the ability to be falsified, whereas Einstein's theory was at risk of being disproven by the 1919 solar eclipse experiment.

05:02

📚 Popper's Philosophy on Scientific Knowledge and Falsification

The second paragraph delves into Popper's philosophy of science, which challenges the traditional scientific method and emphasizes the value of falsification. Popper argued that all scientific theories should be open to being proven wrong, and that the pursuit of truth involves the continuous testing and revision of beliefs based on new evidence. He contrasted the approach of seeking confirmation with that of seeking disconfirmation, using the analogy of proving or disproving the existence of Santa Claus to illustrate the point. Popper's insights have significantly influenced modern scientific thinking, advocating for testable, refutable, and falsifiable hypotheses as the hallmark of scientific inquiry.

Keywords

💡Pseudo-science

Pseudo-science refers to beliefs or practices that claim to be scientific but do not adhere to the scientific method's rigor. In the video, Karl Popper distinguishes between true science and pseudo-science, using Freud's psychoanalysis as an example of the latter because it could seemingly explain any data point, thus lacking the ability to be falsified.

💡Scientific Method

The scientific method is a systematic approach to investigating and understanding the natural world, based on empirical evidence and subject to testing and refinement. The video discusses the traditional understanding of the scientific method, which involves observation, hypothesis formation, and testing without preconceived notions, contrasting it with Popper's emphasis on falsifiability.

💡Falsifiability

Falsifiability is a cornerstone of Popper's philosophy of science, which posits that for a theory to be scientific, it must be susceptible to being proven false. The video illustrates this with Einstein's general theory of relativity, which was at risk of being disproven by the 1919 solar eclipse observations.

💡Confirmation Bias

Confirmation bias is the tendency to favor information that confirms one's existing beliefs or hypotheses. The script mentions that Freud's psychoanalytic theories could be used to explain almost any behavior, thus exemplifying confirmation bias, as opposed to the falsifiable predictions of Einstein.

💡Risk

In the context of the video, 'risk' is associated with the vulnerability of a scientific theory to being disproven. Einstein's theory took a risk by making a bold prediction that could have led to its rejection if the eclipse results contradicted it, unlike Freud's theories, which were less risky as they could adapt to any evidence.

💡Theory

A theory in science is a well-substantiated explanation of some aspect of the natural world, based on empirical evidence and tested and refined over time. The video discusses how theories should be prohibitive, ruling things out, and how they can be scientific only if they are testable and refutable.

💡Prediction

Prediction in science is the act of projecting or forecasting outcomes based on a theory. The video contrasts Freud's use of past data to explain current phenomena with Einstein's approach of making predictions about future events, such as the behavior of light during a solar eclipse.

💡Irrefutable

An irrefutable theory is one that cannot be tested or falsified. Popper argues against such theories in the video, stating that for a belief to be scientific, it must be open to testing and potential refutation.

💡Belief

Belief, in the context of the video, refers to an individual's acceptance of a theory or idea as true. Popper emphasizes that beliefs should be contingent on data and subject to revision in light of new evidence, highlighting the importance of maintaining an open mind to achieve closer proximity to truth.

💡Probability and Contingency

Popper views knowledge as being about probability and contingency, meaning that our beliefs should be based on what seems most probable given the current evidence and should be open to change as new evidence arises. The video illustrates this by discussing how certainty is not the goal in science, but rather a willingness to revise beliefs based on evidence.

💡Santa Claus

The video uses the example of Santa Claus to illustrate the concept of falsification. It suggests that one can find evidence to support the belief in Santa Claus everywhere but that the true test of the belief's validity is to seek evidence that disproves it, aligning with Popper's philosophy of science.

Highlights

Karl Popper distinguished between science and pseudo-science, emphasizing the importance of testability and falsifiability in scientific theories.

Popper observed different methods used by Einstein and Freud, noting Freud's theories could accommodate any data, while Einstein's predictions were risky and could be disproven.

Einstein's general theory of relativity was put to a test during a solar eclipse, demonstrating the scientific method of making bold, testable predictions.

Freud's psychoanalytic theories were criticized by Popper for being able to explain any outcome, thus lacking the ability to be falsified.

Popper argued that the traditional scientific method, which relies on observation and hypothesis formation, is flawed because it starts with preconceived notions.

Popper's philosophy suggests that all scientific theories should be prohibitive, ruling out possible outcomes and allowing for the potential of being proven false.

He proposed that only theories that are testable and refutable can be considered scientific, as opposed to those that are merely confirmatory.

Popper's insights have influenced modern scientific thinking, focusing on the process of disproving rather than proving scientific hypotheses.

The philosopher highlighted the importance of being willing to give up a theory when it is disproven, as a sign of scientific integrity.

Popper's work teaches us about the nature of knowledge, suggesting that beliefs should be contingent on data and open to revision with new evidence.

The concept of irrefutable theories was critiqued by Popper, who stated that for a theory to be scientific, it must be testable and potentially falsifiable.

Popper's approach to knowledge emphasizes probability and the acceptance of uncertainty as a pathway to truth.

The philosopher's ideas challenge the traditional pursuit of certainty in knowledge, advocating for an open-minded approach to beliefs.

Popper's work has practical applications in how we evaluate theories and beliefs, urging us to seek disconfirmation as a means of testing truth.

The episode concludes by relating Popper's insights to broader philosophical questions about knowledge and belief, particularly in relation to the concept of God.

The Crash Course Philosophy series is sponsored by Squarespace, offering a platform for individuals to share their ideas and create an online presence.

The production of the series is supported by PBS Digital Studios, which is associated with a variety of educational and entertaining content.

Transcripts

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Imagine being alive when Albert Einstein was developing his theories of relativity.

Or witnessing the birth of psychology, as Sigmund Freud and psychoanalysis took over the scientific mainstream.

The early 1900s was an amazing time for Western science.

There was another figure on the intellectual scene when these great minds were at work.

Young philosopher Karl Popper was born in Austria -- Freud’s home turf -- but built

his career in Britain, giving serious consideration to the new ways that these and other scientists

of the time were thinking about the world.

And after looking at different methods that people like Einstein and Freud were using,

Popper came to understand that not all scientific achievement was created equal.

He ended up making an important distinction, between science … and what he called pseudo-science.

And in the process of doing this, he taught us volumes about the nature of knowledge itself,

and how we can best test it, and challenge it, to bring us closer to the truth.

[Theme Music]

Emerging at roughly the same point in history, Freud and Einstein both made predictions that

they hoped would help us better understand our world.

Freud, concerned with the individual psyche, predicted that our childhood experiences would

have a heavy bearing on who we grew up to be.

Meanwhile, Einstein waited patiently for a solar eclipse that could disprove his entire

general theory of relativity, depending on what it would reveal about how light travels through space.

And then there was Karl Popper, born in 1902, who grew up to observe these predictions with

keen interest. As a young scholar, he learned about the psychoanalytic theories of Freud,

and attended lectures given by Einstein himself about the rules of the universe.

And he noticed that these great thinkers used different methods.

For example, Popper observed that Freud was able to make just about any data point work

in service of his theory. Freud could explain a person’s intimacy issues both in terms

of not being hugged enough as a child, or in terms of having been hugged too much. Meanwhile,

almost any behavior on the part of a female could be explained in terms of penis envy.

Evidence to support Freud’s theories seemed to be everywhere!

But Popper saw that Einstein was making a different type of prediction.

Instead of looking backward, and using past data to “predict” the present, he was

looking ahead, and predicting future states of affairs. Einstein’s theory was truly

risky, Popper realized. Because, if the future didn’t match his predictions, then his theory

would be conclusively disproven. If the results of the solar eclipse in 1919 had been different,

general relativity would have been finished.

Freud, on the other hand, could always just read the past differently, so as to maintain

some kind of confirmation of his theory.

Suddenly, Popper understood the difference between the science that Einstein was doing,

and what Freud was doing, which Popper rather snootily referred to as pseudo-science.

Now, whether psychology today is considered a hard science or a social science or some

other kind might be debatable. But you won’t find many mainstream thinkers who consider

it pseudoscience. But still, nearly a hundred years ago, when Popper was reaching these

conclusions, no modern philosopher had really characterized what “science” truly meant

-- and what the implications were for the pursuit of knowledge.

The traditional understanding of the scientific method, going all the way back to the ancient

Greeks, relied on the belief that, to look at the world with a scientific eye is to observe

with no preconceived notions.

You simply look, see what you see, and then develop hypotheses based on those observations.

So, you look at a swan, and you notice it’s white. You look at another swan; it’s white too.

You look at enough white swans, and eventually you form the hypothesis that all swans are white.

This is what Freud said he was doing: Observing relationships -- but instead of it being between

the relationship swans and colors, it was between particular human phenomena and human behavior.

But Popper argued that everyone has preconceived notions of some kind. We all start out with

a hunch, whether we admit it or not.

After all, what you decide to observe is determined by what you already care about enough to observe

in the first place and the fact that you care about it so much also means that you already

have some beliefs about it.

So, what does that tell us about Freud?

Popper became convinced that methods like his that only served to confirm beliefs were pseudo-science.

And they could be used to prove anything.

Consider the existence of Santa Claus. If I try to find evidence of Santa’s existence,

I’m going to find it, easily. The world is filthy with evidence of Santa Claus! There

are presents under the tree on Christmas morning. There’s the guy at the mall. And then there

are all those songs, and stories, and tv shows, and movies – they combine to confirm your belief in Santa.

But Popper would argue that it’s only by seeking to disprove Santa’s existence that you can demonstrate his unreality.

So the question is, when we begin to test a theory, are we looking to confirm it, or disconfirm it?

This is the key point, for Popper – science disconfirms, while pseudoscience confirms.

He elaborated on this insight by establishing a series of distinct conclusions about science and knowledge.

First, he said, it’s easy to find confirmation of a theory if you’re looking for it.

Remember the presents under the tree? If you’re looking for proof that Santa exists, you’re not

likely to keep searching for contradictory evidence after that.

Second, confirmation should only count if it comes from risky predictions – ones that

could actually destroy your theory. Because, Popper observed that every good scientific

theory is prohibitive – it rules things out.

This might sound strange, because no one wants to be wrong, but Popper says that every false

belief we discover is actually good, because that gets us that much closer to believing only true things.

Next, Popper argued that the only genuine test of a theory is one that’s attempting to falsify it.

So, if you were to test for Santa’s reality, your method would require you to try to prove that he doesn’t exist,

rather than proving that he does. So, you stay up all night, waiting to catch him delivering his presents.

This is risky, because if the person who actually shows up to put presents under the tree is your Dad,

then you’ve destroyed the Santa hypothesis.

On a very similar note, Popper also pointed out that irrefutable theories are not scientific.

If it can’t be tested, then your theory doesn’t have much value.

Like, you can only confirm that Santa is real by doing everything in your power to prove

that he’s imaginary, and then failing to do so. So you need to be tugging on Santa

beards at the mall. You need to investigate reports of Santa sightings, and other weirdoes

caught breaking into peoples’ houses through their chimneys. If you want to be able to

really trust in your belief in Santa, in a genuinely scientific way, you need to put

your belief to the test, in every way you can imagine.

This is where Popper says that you have earned the right to call a theory scientific.

And finally, once you’ve disproven your theory, Popper said, you need to be willing to give it up.

I mean, you can still cling to the Santa myth, even after catching your Dad putting gifts under the tree,

by accepting his lie that Santa had dropped the gifts off earlier, and that he was just “helping.”

But, if you’re a scientist, you’re gonna have to be willing to let your beliefs go.

Accept the evidence. Move on.

And this is the modern scientific thinking that we accept today: Testable, refutable, falsifiable.

You don’t seek to prove scientific hypotheses right, you only prove them wrong.

A lot of this might seem so obvious that maybe you’re wonder why we’re talking about it.

But that’s how right Popper was – he was one of those rare philosophers who actually

managed to hit on an idea so right that we don’t even really argue about it anymore.

So, it sounds like I’ve been talking mainly about science all this time. But Popper and

his insights actually tell us a lot about knowledge, in the philosophical sense.

For Popper, knowledge was about probability and contingency. We are justified in believing

whatever seems most probable given our current data. And we should always be willing to revise

our beliefs in the light of new evidence. In other words, our belief should be contingent on the data themselves.

This wouldn’t have satisfied Descartes, who was always concerned about certainty.

But Popper never thought that certainty was possible in the first place. If anything,

he thought being certain of something causes you to close your mind, and that’s

not what we want. Always remaining open to the idea that your current beliefs might be

wrong is the best way to get ever closer to truth.

So where does this leave us?

Remember, we started out trying to prove that we know the things we thought we knew. But

you have to be open to the idea that your beliefs might be false -- because that’s

the only way that holding onto them can really mean anything. Otherwise, we’re all just

believing whatever we want, with no grounds for adjudicating between beliefs.

You should keep that in mind, because that’s the name of the game for the rest of this course.

You only get to believe the things you have reasons for, and we’re going to

start with the area that is hardest for most people – God. Hope to see you there.

Today you learned about Karl Popper, and his insights into science, pseudoscience, and

knowledge -- which might best be summarized as science disconfirms, while pseudoscience confirms.

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