ฝึกพูดภาษาอังกฤษด้วยเทคนิค Shadowing จากวิดีโอ: Philosophy of Science Lecture #2: Verificationism

Thank you.

A lot of people have felt that the distinguishing thing about science

that makes it so special and cuts it off from other ways of examining the world is the method that science uses, some characteristic rigorous method

that ensures the accuracy of its conclusions better at least than do the methods in other areas of inquiry.

One very influential way of characterizing scientific method is in terms of its use of observation,

especially experimental test.

Now, while experiments are easier in some sciences than in others, nonetheless, the whole idea that theories should be testable,

that theories should be observable, that has been extraordinarily influential in the history of science.

Today, we're going to look at one popular and historically influential view about science's method called verificationism.

The man who invented the name positivism in the middle of the 19th century was August Comte.

It's spelled like August, except it's got an E on the end, just like the month.

And his interest was to banish metaphysics.

He thought that metaphysics had been the bane of all intellectual work that had gone before the 19th century,

and that the developments of science in the 17th century and in the 18th century, and then also through the first part of the 19th century,

had shown that the proper way to undertake an understanding of the world is science.

And I guess he meant by that something like rigor.

Now, he presumably had some sort of notion about what scientific method was since he meant to banish all other methods, calling them all metaphysical.

But in particular, he thought that all theological modes of reasoning ought to be kicked out.

These were misleading, led only to false conclusions, and hurt people.

So what he hoped for was a new dedication of society to science.

He believed on what we might now call sociological grounds that societies needed to have things like religions,

and so what he wanted to do was to replace all the organized and standard religions with the worship, if you like, of science.

Now that's sort of an interesting concept, I suppose.

He also felt that all areas of inquiry should be radically reformed to reflect this scientific bias,

or the scientific inclination, let's say.

He wouldn't have said bias, I think.

But that was his view, and positivism was widely regarded.

Just because science had been so successful, it was almost a cult among intellectuals for a while, the whole notion of positivism.

Again, meaning at that time, kicking out metaphysics, which was thought to be speculative and old.

As a matter of fact, you get analyses from people.

They talk about the religious mode of reasoning as being antiquated

and sort of located in tribes and maybe in the dim and dark history of Western civilization.

And then there's the metaphysical modes of reasoning.

which are sort of philosophical, they're kind of superior to theological modes of reasoning,

religious modes of reasoning, but the metaphysical modes of reasoning ought to be surpassed themselves by scientific modes of reasoning.

So the new future of society is going to be scientific, as far as Comte and his followers were concerned.

Now, his followers were not some small cult.

Does the name Ernst Mach ring a bell?

You nod yes.

Who is he?

He just rings a bell.

Does anybody know who Ernst Mach is?

He is a German scientist.

Does anyone know in what field?

Pardon?

Physics, generally.

Mechanics.

He wrote a book called Die Mechanique.

Why does the name Mach ring a bell?

I'm sure that a lot of you don't know anything about the history of science.

Mach 1, Mach 2, Mach 3.

That's the speed of sound.

Mach 1 is the speed of sound

and his name is now attached to the measure for the speed of sound in an airplane to travel twice

or three times, the speed of sound is said to travel at Mach 2 and Mach 3.

And that label owes its name to Ernst Mach.

He was a very influential German physicist, but he was a positivist.

He thought that metaphysics should be banned.

And what that meant to him, for example, in the 19th century, along with lots of other scientists who were right at the cutting edge of chemistry and physics,

and who are building what we now call the atomic theory of matter.

What that meant to them, to the positivists in that crowd, was that the atomic theory of matter should not be taken seriously as a characterization of reality.

What they said about it, Ernst Mock in particular and other positivists among the physicists, was these are all clever calculation devices, if you like.

These theories offer us a means.

We're going to return to this later when we talk about instrumentalism in science.

I just want to note this right here.

He said we should not take seriously the idea that there really are atoms out there that make up molecules.

These things are unobservable.

You can't see them.

Nonetheless, that doesn't mean we have to kick out the theory.

The theory is a nice device for organizing data, if you like.

It's a nice device for organizing data.

It's sort of like a filing system.

A theory allows us to assign certain variables to talk about, it's a language, it allows us to talk about phenomena in a certain way,

but we shouldn't get metaphysical about it.

We shouldn't think that just because the theory is useful in some way that there really are these things called atoms, I mean that would be ludicrous,

and so that's the kind of attitude

that i hope to characterize here is you know i want

you to understand is instead of 19th century positive hoping for not

and positive uh it's a sort of an unusual usage of the term

but what they meant by the reason they were talking about positivism is

because they were tired of what they took to be speculative

uh attempts to explain nature what they wanted was down to earth

verifiable that's the first time you've heard that word verifiable statements about the physical world.

And when you start talking about things that are not observable, then you're talking about things that are not verifiable.

You're starting to start getting spooky here, you're getting philosophical, metaphysical, and this is to be resistant.

In the middle of the 19th century, it still probably seems that they had only very recently managed to free,

to It will liberate science from the speculative character that it has had before the 17th century, say.

And I think that a lot of them, when they started looking at theories like the atomic theory, which began to postulate these that you couldn't see,

you couldn't taste, you couldn't feel, it sure did look like that old metaphysical stuff coming back in.

It looked like impetus.

It looked like natural places, the kinds of things that I mentioned Aristotle used to talk about that really didn't look scientifically.

And so movement sprang up, the sort of vanity.

That was 19th century positive.

So positivism is to be equated with testability.

What different positivists said And testability was the criterion of, that's going to vary from theory to theory.

But what we're going to start off with is a hardcore version.

And we're then going to go to a foster core version, positive version.

Actually, we're going to, this is going to all be part of something called verification

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because there's another branch of positive version that we'll talk about next time.

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We'll talk about these today.

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So, next time we'll talk about falsification.

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It also expresses...

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the importance of tests, but in a different sort of way.

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Now, so positivism generally, all these theories we're going to discuss this time and next time,

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is marked by its emphasis on tests, on observability, at least observability in principle,

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and it's also positivism always emphasized the the deployment of tests in as experimental tests of theory

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and try to talk about the logic of the relationship between theory and tests now

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what goes what I'm calling the hardcore hardcore verification ism is associated with what with the verifiability criterion of meaning.

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And the verifiability criterion of meaning says quite plainly and simply, if something, you choose what?

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If proposition, sentence, theory, whatever, belief, if it's to have any meaning at all,

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it must be verifiable, right?

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Now, this is a very strong criterion.

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That's why I call it hardcore core.

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This is a criterion of meaningfulness.

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In other words, what they're saying is anything that's not verifiable, and they've got metaphysics in the back of their mind, they've got any theory like the atomic theory that,

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as far as you can tell, isn't verifiable.

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Now, it's open to question whether it is or it isn't, but Mach didn't think it was.

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It's certainly true.

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They're talking about all religious theories that talk about gods that can't be seen, heard, felt, tasted, or whatever.

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These are not just false.

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I mean, they're not even good enough to be false or true.

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They're meaningless.

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I mean, if you say, are there gods or not, what the hardcore verificationist is going to say is that question isn't even good enough to be true or false.

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I mean, I can't even tell you it's false.

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It's just a meaningless question.

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It's gibberish.

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It's garbage.

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It's not that you have to have verified it in fact.

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There are things that are going on outside the solar system

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or even on the dark side of the moon that you can make perfectly meaningful propositions about,

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according to the hardcore verificationists.

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You can make perfectly reasonable propositions about these things that are perfectly meaningful, provided that you have at least some idea of how one might verify it.

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It doesn't even have to be technologically possible, but if you can say, well, all right, what I mean by saying

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that there are things going on on the dark side of the moon is

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that if someone were there or if some mechanism were there that could make suitable recordings, it would record suitable things.

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You know, like it might take pictures, or it might make sounds, or it might record, if you're saying there's earthquakes on the dark side of the moon, even though there are no seismographs up there,

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all you have to do is be able to specify what

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sort of thing in principle would count as the kind of observation that would distinguish between the truth and falsity of that.

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All you have to do is be able to say, well, if we did have a seismograph up there, then what my sentence comes down to is that it would be registering something other than the norm.

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So all I mean is that you should, in order for the sentence to be meaningful, you should be able to specify what sort of thing would count as a verification of it,

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and what you assert when you assert the thing is that you would observe x if you had the suitable equipment.

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What this is just supposed to do is show that they're not being totally unreasonable when they try and banish metaphysics.

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They just want to banish things that don't make any difference.

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So that, for example, if I were to tell you that back there in that corner, everyone look, please, back there in that corner just below the clock is a six -foot -tall undetectable bunny.

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And I say it's undetectable.

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I mean it is absolutely undetectable.

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There's no way at all to detect that.

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There's no way to determine whether that's true or false.

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There's no way to verify it.

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Well, the positivist would say, well, it's all very nice.

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but, you know, if it's in principle unverifiable, it's meaningless.

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You've made no proposition whatsoever.

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Now, if I said you can't see it, but indeed here are some tests you could perform.

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I mean, you could put a carrot over here and it would be gone after 20 minutes.

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Verification would say, ah, well, maybe that's not so meaningless after all.

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At least you've offered us some potential observation that could be made that would tend to verify your assertion.

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But now, if we've got two propositions, two different propositions that would equally well explain the missing carrot,

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one of them, you know, the big six -foot -tall otherwise undetectable rabbit,

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two, maybe there's somebody that likes carrots and they're sitting over there nibbling in the back of the room,

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well, the positivist has some definite thoughts about which one we should prefer.

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It's the one that requires less of an extension of our normal testing procedures and requires less imagination and speculation.

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Gods, I think the hardcore verifications probably thought they'd banish most or all gods altogether by this criterion, but I suppose if there are some,

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you know, some people would claim that, no, I mean, you know, God is not somebody who, or something that is undetectable.

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I mean, you can see God's, you see evidence of God in all sorts of things.

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The verificationist wouldn't say that that's meaningless, but would point out that there are other ways of explaining, you know, would say that there are other ways of explaining the same things

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that God supposedly explains that do not require this extra hypothesis so that the hypotheses of physics,

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for example, and the physics plus evolutionary biology say,

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and the hypotheses of God are empirically equivalent if they explain the same data.

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And what we should do is to prefer the more parsimonious one.

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This is called Occam's razor.

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We should prefer the one that requires us to postulate fewer unusual, or in this case, supernatural sorts of things.

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Now, what it does banish is any divinity that is absolutely 100 % unverifiable, undetectable, unobservable.

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And what the verificationist wanted to say is not just,

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well, let's focus our attention here on a class of statements that are exceptionally interesting from the point of view of science,

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namely the ones that are observable or have observable consequences is they wanted to say,

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no proposition that is unverifiable is even meaningful.

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That was a very bold, it was anti -metaphysics.

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They want to say metaphysics is meaningless because unverifiable.

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And in a way, they defined metaphysics as that which is unverifiable.

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Remember what Mach says about atoms.

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He says, look, I mean, well, it might be a useful device for some purposes, but we shouldn't take seriously the idea that these things exist. And B .F.

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Skinner would say, this is quite apart from other things that Skinner might say, but he would say, there's nothing wrong with a mentalistic,

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to say that I have a feeling or that I have a mind, if you're just kind of informally speaking.

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He said, my mind tells me this, or I have a certain feeling.

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That's a perfectly decent expression, according to Skitter.

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But we don't have things called feelings that are somehow stored in there.

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No, we feel.

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It's an activity.

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It's a process.

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It's not a thing we have.

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And we've got to be careful about the implications of these modes of speaking.

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Well, this is precisely what the positives want to say.

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These modes of speaking might be very, very useful for certain purposes.

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But beware if you suddenly become committed to little things called atoms or electrons or quarks.

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I mean, you can't see these things.

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You can't even in principle see these things.

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The argument about whether atoms even had structure is, you know, centuries old.

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And the argument about whether electricity is to be understood as a particle -like

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or wave -like phenomenon is still kind of weird to this day.

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So whether these little things called particles, the electron is supposed to be the particle that bears the negative electric charge,

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it's still kind of dubious how you're supposed to talk about those things.

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There's a nice mathematical language, but what English words to use to describe these phenomena is not at all clear.

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And what the positivists in any era would say is these mathematical languages do not abandon them.

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But remember, they're just notation devices.

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They're calculation devices.

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They help us get from data to data.

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We've got some input data.

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We plug them into our equations.

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And these equations allow us to make accurate predictions about what observables.

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And that's all that counts is that we're able to make accurate predictions about what will happen in an experimental setting.

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So you might want to say, we observe an electron.

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It doesn't matter.

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Forget about the electron.

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The electron is just a convenient device to predict

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that under certain circumstances we will hear a click on

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that Geiger counter or that we will see a cloud trace in

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that Wilson cloud chamber or that we will get a certain result on the oil drop experiment.

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That's what's really going on here, according to the positivists.

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Our theories are mere calculation devices.

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We shouldn't take them seriously as talking about things in the external world.

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And the criterion for meaningfulness is verifiability.

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If a sentence or proposition, whether scientific or not, if it's not verifiable,

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If there's no way that you can even say how we should go about demonstrating the proposition to be true, well then, it's not meaningful.

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And I want to return to the remark made up there, and then we'll get into another brand of verificationism, the soft core, because it was the hardcore verificationists,

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to their credit, that one day opened up their eyes and said, whoop.

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They said, uh -oh.

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And it involved the verificationist criterion of meaning itself.

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The verifiability criterion of meaning says what?

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It says a proposition is meaningful only if it is verifiable, otherwise meaningless.

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Now, what kind of thing would it be to verify that?

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I mean, how would you demonstrate it to be true?

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It's not the sort of thing that you could demonstrate to be true.

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It's sort of like a suggested norm.

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It's saying, what it says tacitly is, we should no longer take seriously things.

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It's a should statement, right?

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It says we should steer clear of metaphysics.

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We should not take seriously any metaphysical propositions.

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We should only attend to verifiable propositions.

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It's a norm.

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It's not verifiable.

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Well, if not verifiable, then what on the verifiability criterion of meaning?

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Gibberish.

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Meaningless gibberish.

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So they said, whoop, and they fell back with a variety of different sorts of reactions.

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Fell back to the soft core position, which involves not a verifiability criterion of meaning,

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but instead the verifiability criterion of demarcation.

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Those words we're going to have to talk about, and we will.

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But first, one more question.

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Yes?

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What if you had a theory that was not verifiable at a present time?

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If you mean is not verifiable because we lack the technology,

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then that doesn't stand in the way of its being meaningful even on the hardcore theory, even on the verifiability criteria of meaning.

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All that's required is that there be some way in principle, not in fact, that you could specify,

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like, for example, having a seismograph on the dark side of the moon, something that you could explain what you meant,

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what you would expect to find out if you performed the relevant tests.

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Tell us what the relevant tests would be.

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Like you could say, I think there's a giant zebra behind Pluto

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that always stays back there and we can never see it.

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That can be as meaningful as you please.

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I mean, false in their view, but that's as meaningful as you please if what you mean is, well, if we had a spaceship and went around back there, there'd be this big, giant zebra.

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I mean, if that's what you, that's fine.

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That makes it meaningful.

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The problem is when you say, I think there are some things that are just absolutely undetectable.

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They'll say, well, think away, but what could you possibly be talking about?

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What could you possibly mean?

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in saying that there are things that couldn't possibly be detected by sight,

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sound, any means, no machinery, no mechanism could possibly detect it?

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What could you possibly mean?

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I don't know how close this is or not.

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Just in saying that, it struck me as bearing a resemblance to the following thesis, which I think is at least plausible.

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And that's that there's nothing you could say that doesn't try to,

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no description that you can offer that doesn't try to bring the thing described under known categories.

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Like if I try to describe something that's strange or unusual, I will try and tell you what it's like.

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And what I'm doing there is trying to show you what sort of thing to expect, even though I'm telling you it's strange and unusual, it's different.

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It's kind of like this in that respect.

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It's kind of like that in the other respect.

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I think what the verificationists were grappling with was something like that idea, except they wanted to make it a little bit, they wanted to pin it down a little bit better than that.

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So what they said was, you need to specify not just what kind of thing it is,

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but to specify which steps you'd have to take in order to test what you just said.

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That will establish what it means.

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Now then, to perform the tests, we'll decide whether the sentence is true or false.

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Like what the sentence, according to the verification, the hardcore ones, what the sentence about

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that zebra floating out there in space means has something to do with what sorts of things would happen

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if you were on a ship out there, an observing probe out there.

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To specify which readings you'll get, what images you'll get, what pictures you'll get,

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that exhausts the meaning of the sentence.

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You will see something with stripes rather than something without stripes.

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That's why we say it's a zebra.

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That's what it means to say it's a zebra.

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It will look sort of horse -like.

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That's what it means to say.

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That's another part of saying it's a zebra rather than a skunk.

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And it will be very, very large, much larger than the normal horse.

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That's what it means to say it's a giant, right?

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Et cetera, et cetera.

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And the way we flesh out, for the hardcore verificationist, the way we flesh out the meaning of any sentence at all, it doesn't have to be scientific,

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is in terms of what would happen if we did that.

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That's operationalizing it.

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That shows you how you would perform, how you would investigate it, and what you would expect to get.

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Now, let's get in a ship and go out there on the other side of Pluto and look, hot -nosed zebra.

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Now, sentence turns out to be false, but it can't even be false or true until it is meaningful, unless it's meaningful.

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Again, the simple question was, what about stuff we can't now verify, but we manage to verify it later?

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No problem.

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It's meaningful all the way through, as long as you could say what sort of things would have to be done to verify it, even though we can't.

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An example, a case in point, and this is the sort of thing that the verificationists, whether hardcore or softcore, love of.

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Albert Einstein proposed the general theory of relativity in 1916.

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It's an extraordinarily abstract and difficult theory.

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And it was proposed not in order to explain any known anomalies

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or problems or any kinds of experiments that no one could explain.

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That wasn't the problem at all.

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The reason it was proposed is to offer a better organization or synthesis of physics.

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I'll try and explain that a little later.

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So right then in 1916, when it was proposed, there weren't any experiments that were especially well confirmed by that.

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And Einstein and others who were sort of interested in theory had to try

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and think of what kind of experiment could be performed that would verify the theory.

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And it wasn't real easy to do.

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Einstein himself thought up of at least one, and I don't know whether he thought up the other two, but for the longest time, right up into the 50s,

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I think, there were only about three known ways to verify the theory.

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And in 1916 in particular, the one way that seemed likely to be easiest to verify, it couldn't be done for practical reasons.

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There was a war going on.

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So it wasn't until 1919 that the observation was performed.

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And when it was performed, it seemed to verify the general theory of relativity.

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But in those intervening years, the theory wasn't meaningless, according to positivists.

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It's just that Einstein had proposed how to test the theory, thereby establishing its meaningfulness.

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He said, if you perform such and such an experiment, if my theory is right, you'll see this.

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If my theory is wrong, you should see that.

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And that's sufficient to establish its meaningfulness, even though the tests had not yet been performed.

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But of course, we've got a problem.

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Let us see what they did.

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I've suggested that what they've done is to go from the hardcore verifiability or verificationism to soft -core verificationism.

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And in this, they adopt, rather than a criterion of meaning, a criterion of demarcation.

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Now, the whole idea of a criterion of demarcation was actually introduced, I mean, that expression, criterion of demarcation, was actually introduced later by Karl Popper,

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who we're going to talk about next time.

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But the general idea is this.

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What we want to know is what's the difference between science and non -science?

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What is the demarcation line?

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What divides science from pseudoscience?

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The way Popper explained it, or actually I should be careful here.

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His student, Imre Lakatos, explained it this way.

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He was telling this story about Popper.

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Now I'm taking Lakatos to know what Popper went through.

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But the idea was this.

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Back in the teens, 1916, 17, 18, 19, 20, when Popper was going to school in Vienna,

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Vienna was an extraordinarily booming place.

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I mean, everything was going on there.

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First of all, it just left the Austro -Hungarian Empire, which was just on the verge of collapse because of World War II,

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but it had been collapsing for some time, probably for 15 years.

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The war will be the end of it.

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So in much the same way as the Soviet Empire is collapsing right now, at that particular time, the Austro -Hungarian Empire was collapsing.

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Now, what's interesting is that as the Austro -Hungarian Empire collapsed, an empire

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which had preached the evils of socialism for all of its

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days since Karl Marx had written in the middle of the century,

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the fact that the powers were collapsing meant that everyone felt free to move into this previously forbidden area.

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Karl Marx's scientific socialism, his scientific approach to why it is that societies change.

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They change because of the changing material conditions of production.

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They change because, in the end, of economic forces that are out of the control of revolutionaries, out of the control of state leaders.

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They just are facts that leaders and ideologues will just have to deal with.

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I mean, Marx was extraordinarily impatient with ideology and revolutionaries who would try to inflict ideology on history.

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History guides itself by facts.

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And so this was scientific socialism, and this was just all the rage in Vienna.

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At the same time, there was new architecture that was springing up in Vienna, new art forms, brand new sorts of music.

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Freud, Sigmund Freud was in Vienna, and physics was in Vienna.

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I mean, some of the great discoveries were going on in Berlin, but it was in Central Europe in Germany and in Austria,

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where some of the great work was being done in physics in those years.

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And Popper was being educated at that time.

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And so Popper said to himself,

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how is it that I am not as impressed with such supposedly scientific theories as Marx's or Freud's,

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for that matter, as I am with Einstein's?

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I mean, just to take an example, here are several, I mean, what Freud was doing, for example,

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was offering what was billed at the time as the first scientific theory,

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first scientific interpretation of human behavior, of human psychology.

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And so all the intellectuals were flocking.

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And again, there's this influence of positivism that says everything scientific is good.

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And so what Popper says is, well, I do like science, but what is it that makes me suspicious about these things like Marxism and its claim to be scientific,

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or Freudianism and its claim to be scientific?

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And while at the same time I seem to find that I'm a believer in the scientific character anyway, of the general theory of relativity.

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Even though it hasn't been tested yet, it's plainly a scientific theory.

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And even though it may be wrong, it's clearly a scientific theory.

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So he's not talking about what's right and what's wrong.

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He even said, you know, he was kind of sympathetic to Marxism.

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He was sympathetic to Freudianism.

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But he did not think of them as scientific theories.

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What's the difference?

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How come Darwinian or Mendelian genetics and Darwinian evolutionary theory, how come they seemed scientific, he wanted to know.

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But these other things don't.

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What is the criterion I'm using?

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There's some criterion I'm using to distinguish science from pseudoscience, to put it baldly.

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Now, Popper's the one that, now that was when he was in school, and later in the 30s, he offered an alternative to the verifiability criterion of demarcation that we're going to discuss now.

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But the verifiability criterion of demarcation goes like this.

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It says, verifiability is not the necessary condition of meaningfulness.

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Things can be meaningful even though they're not verifiable, like, for example, this sentence, that very sentence.

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Things can be meaningful even though they're not verifiable.

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However, in order to be scientific, ethic, a sentence must be verifiable.

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Scientists, said the soft core verificationists,

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scientists are concerned only with propositions,

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sentences, beliefs, assertions that are in principle verifiable, etc., etc., etc. So it's a softening of the position.

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It's no longer a criterion of meaningfulness, it's a criterion of demarcation.

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And it's here that they would point to theories that are extraordinarily abstract,

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like Einstein's, and explain what the difference is between Einstein's theory of general relativity,

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for example, and some other theory like, well, any arbitrary philosophical theory, Plato's theory of forms, say,

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which you may or may not know about, or Descartes' theory about mind and matter,

403

the bifurcation of the human being into a material and the mental realm.

404

The soft core verification has said the problem with those theories is not that they're meaningless, it's the fact that they're not verifiable,

405

there's nothing you could do to verify one of those theories, just shows that it's not scientific.

406

And so if you're, you know, if you want to do metaphysics, that's fine.

407

It wasn't for the hard core verification.

408

It's the soft core verification.

409

Well, you know, if you want to do metaphysics, that's okay.

410

It might even be useful, helpful, illuminating in some way, but it's not science.

411

If you want to get down to science, then that's when we should stick to these verifiable propositions.

412

Take, for example, Einstein's general theory of relativity.

413

Now, the point, the reason that Einstein was moved to seek

414

and to try to work out the general theory of relativity was because of a fact about the special theory of relativity.

415

It was incomplete.

416

I mean, he knew it was incomplete at the time.

417

What he was trying to do was to formulate the laws of physics.

418

This is what he was trying to do in the special theory of relativity so that they would remain the same.

419

He would get the same formulation of the laws of physics,

420

whether you were on an object that was stationary or whether it was in motion with respect to some arbitrary reference frame.

421

He'd wanted to sort of simplify the laws of physics

422

so they would come out the same from any so -called inertial frame of reference,

423

that is, frames of reference that were either at rest with respect to one another or in uniform motion,

424

uniformly motion with respect to one another.

425

Not, in particular, the special theory of relativity did not formulate the laws of physics in such a way

426

so that they would come out the same on an object that was accelerating with respect to another frame of reference.

427

So that, for example, the laws of physics would have to be formulated differently on an object that was rotating another object, like the Earth around the Sun,

428

than it would from the point of view of the Sun.

429

Now, this was an embarrassment.

430

I mean, not an embarrassment, but this was an incompleteness in the special theory of relativity that needed correcting.

431

And so what Einstein spent time doing is trying to figure out just how to reformulate the laws of physics

432

so that they were completely general.

433

so that they would appear to be the same no matter whether you were on a, you know, just take an arbitrary frame of reference like the center of the sun,

434

they would be completely the same whether you were at the center of the sun, of course you'd be pretty warm there, or whether you were at rest with respect to the center of the sun,

435

or whether you were moving in uniform linear velocity with respect to the sun, or whether you were accelerating toward the sun, or accelerating the way from the sun, or orbiting the sun.

436

He wanted perfectly general laws of physics, laws of motion especially, that could be formulated so that they would come out the same for all those perspectives.

437

Now, that was his reason.

438

It was a systematic reason.

439

That was his main reason for trying to figure out the general theory of relativity.

440

Oh, I'm sorry.

441

Okay, so his reasons didn't have anything to do with trying to explain the perihelion of mercury,

442

nor were there any other phenomena that he was trying to accommodate in going from the special theory to the general theory.

443

Indeed, he was always mostly a systematic thinker and a generalist, very abstract.

444

Okay, so anyway, he formulates the theory.

445

It's all abstract work, all looks philosophical.

446

I mean, this is why it's a neat test case, because his reasons were abstract, didn't have anything to do with experiments or observables.

447

The theory that came out was extraordinarily abstract and looked really strange.

448

Really, really strange.

449

Let me give you an example of its strangeness.

450

In the normal course of things, we're taught Euclidean geometry.

451

And among the axioms of Euclidean geometry is this one.

452

Here is a, let's say the surface I'm drawing on is a Euclidean plane.

453

And the axiom goes like this.

454

If you've got a line in that plane and then there's a point off that line, but still on the plane,

455

then there is one and only one line that you can draw through that point parallel to that line in that plane.

456

Now, that's a lot of words, right?

457

It's a complex axiom to state, but if I stated it well enough, it should be obvious to you.

458

Does it seem obvious that, of course, that's true, that there's one and only one line parallel to that line through that point?

459

Not for Carl.

460

Well, okay.

461

But in any case, that is the fifth Euclidean axiom.

462

Now, it is so clumsy to say that for centuries, you know, because Euclid figured, Euclid was a student of Plato's, or I'm sorry, Aristotle was a student of Plato's and Euclid was a student of Aristotle.

463

So this is an old system, Euclidean geometry.

464

It's so clumsy that for centuries, people were trying to figure out whether they could possibly derive this one from the other four, which were much more simple.

465

And if they could just have a system of four axioms and not this clumsy one, that would be so nice.

466

Well, they never were able to do it, but part of that effort in the 19th century went this way.

467

A lot of people like a man named Riemann, a mathematician named, there's others.

468

Riemann is foremost among them.

469

Lobachevsky comes later.

470

He's another geometer.

471

But just to see if they could prove that this axiom,

472

this fifth one, was deducible from the others, they said, let's go in the back door.

473

Let's try an indirect proof.

474

Equals fifth.

475

Let's try an indirect proof.

476

Let's assume that it's wrong.

477

Let's pretend we can have, let's just say, we can't make sense of this, Let's say we can have two,

478

or three, or four, or even an infinite number of parallel lines through that point in that plane, to that line, et cetera.

479

Let's just assume the contrary.

480

Let's start out with two.

481

Now, we can't picture that, right?

482

That doesn't make any sense to picture, but let's just say it, and let's see if we can derive a contradiction with the other four.

483

Well, they worked, and they worked, and they worked, and not only did they not derive a contradiction, they proved that they couldn't derive a contradiction,

484

and instead, they they produced a perfectly consistent non -Euclidean geometry

485

that just had this new axiom placed in there instead of the old one.

486

And in addition, they then went on to try some other theories, and they got other non -Euclidean geometries.

487

Well, what general relativity theory says, now those were just sort of mathematicians' delights back then in the 19th century,

488

but what general relativity theory says is our universe is not Euclidean.

489

The physical theory that we believe now about the physical universe says it is not Euclidean.

490

But it's not any one of these others, either.

491

What it is is something that varies.

492

The very structure of geometry, the geometrical structure of space -time changes as you move from

493

place to place in the universe as a function of the concentrations of mass.

494

If you get real close to something with a lot of mass, like a star or a sun, the geometry of space changes.

495

The whole picture, the geometry of space changes, And it's very different there or near a black hole, which is even worse.

496

We haven't confirmed that definitely, but it certainly seems like a good theory and it works well with lots of other things.

497

Near a black hole, the geometry of space -time is even more perturbed, more disturbed.

498

And the differences between those places, which are near concentrations of mass, and places that are in relatively free space,

499

the differences in geometry are massive.

500

They're big, big differences.

501

Now, it's that fact that the general theory of relativity predicts that the geometry of space,

502

space -time actually, the geometry of space -time alters in the presence of massive objects.

503

That's the key to Einstein's bright idea about how to test his theory.

504

This is supposed to be a good illustration of the verifiability criterion demarcation.

505

This is supposed to show just the sort of thing that makes Einstein's speculative abstract endeavor a scientific one, as opposed to the equally abstract,

506

equally difficult intellectual endeavors conducted by the philosophers like Plato and the others.

507

Einstein's is different and scientific because verifiable, and it's this key fact about the geometry of space -time,

508

curiously enough, that turns out to be the key to figuring out how to perform a verification,

509

figure out what kinds of steps would be taken to show that his theory is true.

510

The verifiability criterion of demarcation offered by what I've called the soft core

511

verificationists seem to many to really capture the very special feature about science that made it so successful.

512

But as we'll see, even it came under rather or heavy fire, and this for logical reasons.

513

¶¶ Thank

514

you.

515

Thank you.

516

Thank you.

📺 ช่องเดียวกัน

Philosophy of Science Lecture #1: Introduction

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✨ วิดีโอแนะนำ

106 ประโยค

คำศัพท์และข้อสังเกตด้านการพูดสำหรับบทเรียนนี้

วิดีโอนี้มี 516 ประโยค และ 6737 คำ สำหรับฝึกพูดตาม ช่วงที่มีเสียงพูดยาว 45:57 ผู้พูดพูดด้วยความเร็วสม่ำเสมอ ประมาณ 147 คำต่อนาที เหมาะกับการฝึกพูดตาม 83% ของคำอยู่ใน 3,000 คำที่ใช้บ่อยที่สุดในภาษาอังกฤษ ส่วนที่เหลือควรดูไว้ก่อนเริ่มฝึก

คำศัพท์สำคัญในวิดีโอนี้

คำที่ควรเรียนรู้ 15 คำจากวิดีโอ พร้อมคำอ่านและความหมาย:

คำศัพท์	คำอ่าน	ความหมาย
physics คำนาม	/ˈfɪz.ɪks/	ฟิสิกส์
geometry คำนาม	/d͡ʒiˈɑ.mə.tɹi/	เรขาคณิต
meaningless คำคุณศัพท์	/ˈmiː.nɪŋ.ləs/	ไม่มีความหมาย, ไร้ความหมาย
abstract คำนาม	/ˈæbˌstɹækt/	บทคัดย่อ
experiment คำนาม	/ɪkˈspɛɹ.ə.mənt/	การทดลอง
principle คำนาม	/ˈpɹɪn.sɪ.pəl/	หลัก, คติ
proposition คำนาม	/ˌpɹɑpəˈzɪʃən/	ประพจน์
specify คำกริยา	/ˈspɛs.əˌfaɪ/	ระบุ
atom คำนาม	/ˈætəm/	ปรมาณู, อะตอม
observation คำนาม	/ˌɑbzɚˈveɪʃn̩/	การสังเกต
phenomenon คำนาม	/fəˈnɒm.ɪ.nən/	ปรากฏการณ์
electron คำนาม	/ɪˈlɛk.tɹɑn/	อิเล็กตรอน
parallel คำคุณศัพท์	/ˈpæ.ɹəˌlɛl/	ขนาน
norm คำนาม	/nɔːm/	บรรทัดฐาน
particle คำนาม	/ˈpɑɹtək(ə)l/	อนุภาค

กริยาวลีที่คุณจะได้ยิน

คำศัพท์	ความหมาย
go out คำกริยา	ออก, ออกไป

ไวยากรณ์ในวิดีโอนี้

โครงสร้างที่ผู้พูดใช้บ่อยที่สุด พร้อมคำพูดจริงจากวิดีโอ:

โครงสร้าง	ในวิดีโอ
ประโยคเงื่อนไข if + อนุประโยค, will/would + กริยา — เงื่อนไขและผลลัพธ์	if my theory is right, you'll see
Present perfect have/has + กริยาช่อง 3 — เหตุการณ์ในอดีตที่ยังเกี่ยวข้องกับปัจจุบัน	have felt · has been · you've heard
Passive voice be + กริยาช่อง 3 — เน้นสิ่งที่เกิดขึ้น ไม่ใช่ผู้กระทำ	be kicked · was thought · being antiquated
Relative clauses who / which + อนุประโยค — ข้อมูลเพิ่มเติมเกี่ยวกับคนหรือสิ่งของ	man who invented · metaphysics, which was · that which is

การออกเสียงที่ควรระวัง

ผู้พูดใช้รูปย่อและรูปลดเสียง 125 ครั้ง เช่น they're, can't, I'm ให้พูดแบบสั้นตามที่ได้ยิน

เสียง “th”: mathematical /ˌmæθ(.ə)ˈmæt.ɪ.kəl/, nonetheless /ˌnʌnðəˈlɛs/, sympathetic /ˌsɪm.pəˈθɛt.ɪk/, theological /θi.əˈlɑd͡ʒɪkl/, altogether /ɔl.tuˈɡɛð.ɚ/
เสียง “sh” และ “zh”: verification /ˌvɛ.ɹə.fɪˈkeɪ.ʃən/, proposition /ˌpɹɑpəˈzɪʃən/, unusual /ʌnˈjuːʒ(u)əl/, observation /ˌɑbzɚˈveɪʃn̩/, influential /ɪnflʊˈɛnʃəl/
คำยาว — ลงเสียงหนักให้ถูกพยางค์: geometry /d͡ʒiˈɑ.mə.tɹi/, verification /ˌvɛ.ɹə.fɪˈkeɪ.ʃən/, experiment /ɪkˈspɛɹ.ə.mənt/, proposition /ˌpɹɑpəˈzɪʃən/, unusual /ʌnˈjuːʒ(u)əl/

วิธีฝึกกับวิดีโอนี้

ฟังวิดีโอให้จบหนึ่งรอบโดยยังไม่ต้องพูด แล้วจดคำที่ยังไม่รู้จัก
พูดตามทีละประโยคด้วยความเร็วปกติ ทำซ้ำแต่ละประโยคจนจังหวะของคุณตรงกับผู้พูด
อัดเสียงตัวเองแล้วเทียบกับต้นฉบับ โดยสังเกตคำอย่าง physics, geometry, meaningless เป็นพิเศษ

เทคนิค Shadowing คืออะไร?

Shadowing เป็นเทคนิคการเรียนรู้ภาษาที่ได้รับการรับรองทางวิทยาศาสตร์ พัฒนาขึ้นสำหรับการฝึกนักแปลมืออาชีพ วิธีการนี้เรียบง่ายแต่ทรงพลัง: คุณฟังเสียงภาษาอังกฤษจากเจ้าของภาษาและพูดตามทันที — เหมือนเงาที่ตามผู้พูดด้วยช่วงเวลาห่าง 1-2 วินาที การวิจัยแสดงว่าเทคนิคนี้ปรับปรุงความแม่นยำในการออกเสียง ทำนองเสียง จังหวะ การเชื่อมเสียง การฟังเข้าใจ และความคล่องแคล่วในการพูดได้อย่างมีนัยสำคัญ

เทคนิค shadowing: อ่านคู่มือฉบับเต็มทีละขั้นตอน →

ฝึกพูดภาษาอังกฤษด้วยเทคนิค Shadowing จากวิดีโอ: Philosophy of Science Lecture #2: Verificationism

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กริยาวลีที่คุณจะได้ยิน

ไวยากรณ์ในวิดีโอนี้

การออกเสียงที่ควรระวัง

วิธีฝึกกับวิดีโอนี้

เทคนิค Shadowing คืออะไร?