Vsauce! Kevin here, with a message about your
online existence. Social media is a venomous snakepit of verbal
diarrhea and keyboard garbage because no one can agree on what knowledge is actually knowledge. No matter what the post, or video, or tweet,
or argument is about, no matter what side theyâre on, no matter what they believe,
someone else knows theyâre wrong. They donât know anything. How can two people both be
so confident that they know something when theyâve reached totally different conclusions?
Obviously both canât be right. Right? Whatâs weird, is that it seems pretty simple
to know something. I mean⌠you just know it. You know it because you have some kind
of relevant experience, or you know someone who does and they transferred that knowledge
to you. Or maybe youâve read something you trust, or you know that what an expert in
a particular field says is valid. However it comes to you, that information is an accurate
description of the way the world is. Thatâs knowledge. Right? Wr- Sometimes. The way we tend to think about knowledge is
in terms of âjustified true belief,â a concept that goes back to Platoâs dialogue
between Socrates and Theaetetus in 369 BC⌠and was actually refined and codified by 20th
century philosophers. Itâs a little more modern than it seems, but itâs exactly what
it sounds like: to know something, you need to have justification for it. What sort of
evidence tells you itâs right? Is there enough of it? Are the odds in its favor? And it needs to be true. Is it reality for
you and for others? Does it really hold up to scrutiny? Truth is pretty weird in that
itâs metaphysical -- itâs about how things are, not necessarily what we see. We donât
even have to verify something for it to be true. Quick, pick heads or tails! Go! Iâm
never, ever going to look at the result of this coin flip, but half of you predicted
the true outcome. And then youâve got to believe it: and you
have to recognize it as being true and justified. Look. Here's a very simple example. You look
at a clock to find out the time, because... clocks tell time. You're justified in thinking
a clock is going to tell you the time. The clock says 3pm, which you believe because
it's always been right before and this is what clocks do. It's true because it's actually
3pm. So, congratulations, you KNOW it's 3pm. All of this makes sense. What Iâve just
described is a formal examination of what we all do pretty much all the time. BUT. I can prove your justified true belief, your
knowledge, can be an illusion. For thousands of years the understanding of
what knowledge is was considered etched in stone. Case closed. Until. In 1963, philosopher
Edmund Gettier wrote a short, 3-page paper that completely smashed the justified true
belief simulation. It was such a shift in how we think about knowledge that philosopher
Alvin Plantinga said in 1993 that, âKnowledge is justified true belief: so we thought from
time immemorial. Then God said, âLet Gettier beâ; not quite all was light, perhaps, but
at any rate we learned we had been standing in a dark corner.â How? Gettier claimed that we can satisfy all
three of those conditions and still not actually know something. Letâs revisit our clock example. We looked
at a clock that read 3PM and had knowledge it was 3PM because it satisfied Platoâs
Justified True Belief definition. But. What if the clock was broken and stuck at 3PM?
Do you actually know the time from looking at a broken clock even if itâs accidentally
correct? No. Like "N" "O" no. Not "K" "N" "O" "W" know. That is Justified True Belief
without Knowledge. That is a Gettier Problem. Or think of it like this: there is a cat in
this YouTube video. HOWDY! Sheriff Cat here. I just moseyâd
on into this two-bit town to restore a bit of order. Yâsee, this here wobblinâ-jawed
tenderfootâs been yarninâ the hours away with too much mustard and I aim to set things
straight before the whole corral turns into a bag of nails. I havenât been outside in four months. Anyway, thereâs a cat in this YouTube video.
You know thereâs a YouTube video because youâre watching me record it. Youâre on
YouTube right now. Youâre looking right at Sheriff Cat. Youâre justified in thinking
thereâs a cat in this video, you can decide itâs true with confidence, and you believe
what youâre seeing. Everything here adds up.
And you were right. There has been a cat in this video this whole time -- you were just
right for the wrong reasons. And yeah, you were right, but⌠did you know it? Is THAT
knowledge? Is that knowledge, Luna? Go figure it out. Go figure out what knowledge is. No! Of course itâs not -- you knew NOTHING!
You had a justified true belief, it was accurate, but... it wasnât. So even when youâre
right, how do you know youâre not actually wrong? This calls into question the scientific
method, what we think we know about the natural world, EVERYTHING -- given the ease and prevalence
of Gettier problems, we canât possibly know ANYTHING, RIGHT? *phone rings* Hello?â Wrong. Well, mostly wrong. This is how it
actually works, okay? As scientists, we have a hypothesis, we wonder if something is true
or not true, we propose an experiment. If the experiment supports the hypothesis, then
we say, "Well, maybe my idea was true, but I could be biased. Maybe there was a flaw
in my experiment. Maybe the electrical current had a glitch in the midpoint of taking data." Yeah, but thatâs exactly the kind of uncertainty
Iâm talking about. So I do the experiment again. I try to design
a different kind of experiment to test for the same idea. I get a colleague of mine to
test it. I get them to come up with a new kind of experiment. I get a competitor of
mine to try to show that I'm wrong with an experimental design of their own. And if all
those experiments give approximately the same answer, because there will be statistical
variation, if it gives approximately the same answer, we're onto something. Okay, so, in science you take what seems to
be knowledge and then start to eliminate all those other possibilities to distill what
you think you know. A new truth is emerging in the methods and
tools of science as they are applied to that question, right? So we learn Earth goes around
the sun. That's not going to later on be shown to be false ever. Ever. We got that one. Now,
you can ask more refined questions, okay? What kind of orbit does it have? Is it a perfect
circle? It's a good approximation, but it's not exactly right. So you can ask deeper questions.
Yes, it does go around the sun. What kind of a circle is it? Is it a squashed circle?
Is it elongated? And you keep doing this, and what you end up doing is refining the
answer to the question to a level that satisfies your needs in the moment. Yeah, thatâs how knowledge builds and expands.
So maybe itâs not so much about what we donât know, as what we keep finding out. So you can say, "Will we ever know anything?"
Yes, we know a lot of things. "Will we ever know anything perfectly?" Well, there are
certain things you can ask where you're just counting things. Yes, you can know perfectly.
There's certain crystals where we know exactly where all the atoms are, and we can count
them, so we know exactly how many atoms there are in certain crystals. Yes, there are certain
answers that are precise, but if it involves a measurement? No, it can be ever more refined,
but there could be a point where more refinement just doesn't matter to the aspect of the answer
that you're seeking. So, in science, we are perfectly content when multiple experiments
agree, even if the philosopher isn't. Even if the philosopher is distracted by the possibility
that there might be a deeper truth lurking within the data that we have accumulated.
I don't have a problem with that. I don't have a problem. Yeah, I guess we can hit a point where we
know as much as we want to or need to. And when we hit the end like that we move on to
something else. Science is a continuous journey through the
maze of nature, but not all information is equally uncertain. That's my only point here.
We know how to fly. We know how wheels work and all the other machines in physics. We
know how electricity works. We can use a phone. I got an old-fashioned phone here. It's why
this works. To say, "We can't really know." We do know. That's why you're living longer.
That's why so many things are different about your life today than how your ancestors lived.
Because the methods and tools of science have been applied to questions that curious people
have asked, for the most part, for the betterment of society and for civilization itself. So,
no, I'm not going to wallow in some prospect that we can never know anything. No. We do.
And if you want to think that way, just move back to the cave, because that's really where
you belong. Yeah, I like indoor plumbing. Hey Neil, while
Iâve got you -- thereâs a question that has been killing me for years. It's very,
very important. You've got a question after all that? Okay.
What is it? Okay, ready? Is a hot dog a sandwich?â I have vowed many years ago to never get into
an argument with someone on the definition of a word. All kinds of people love doing
this. I remember growing up. Is it a gum, or is it a candy? Is it light, or is it less
filling? I'm saying no, I'm not going there, because ideas matter to me more than the words
we come up with to describe them. Okay. But I need to know. We need to categorize
this. But just because your brain is... Not yours,
but all of our collective brains want to categorize things, and if something spills out of one
category, we fight about where it belongs. I'm saying no, I'm not having that fight.
I'm not having that fight. In fact, if you want to go there, just invent a new category.
Call it the hot dog category. Okay, it's not a sandwich, it's a hot dog. I'd be happy with
that. Otherwise, no, I'm not spending time arguing this. Please, Neil... Please... Is it a non-bread food sitting between two
surfaces of bread? It's a sandwich. Duh. Bye. Haha!There you have it. Well, this wasn't
plugged into anything... Anyway The Gettier problem exists -- and knowledge
is a lot more complicated than it seems. Excuse me, Sheriff Cat. Happy trails! Sometimes itâs straightforward and irrefutable.
Sometimes itâs murky. Sometimes weâre right and wrong at the same time -- and sometimes
we hit the practical limits of our curiosity and shouldnât really bother getting any
more granular than that. Like Neil says, at a certain point itâs time to move on -- until
we decide we need to go back. In 1972, W. V. Quine, who I referenced in
the âWhat is a Paradox?â video, wrote an essay specifically dedicated to the limits
of knowledge. He opens it by asking, âAre there things that man can never know?â And Roger Shattuck, a writer and literary
professor, explored the consequences of understanding 24 years later in his book âForbidden Knowledge,â
including starting off the entire thing with a seminal question to the human experience:
âAre there things we should not know?â And what about Gettier, who inspired a revolution
in how we think about thought? Philosopher John L. Pollock concluded that Gettier âsingle-handedly
changed the course of epistemology.â Heâs 92 years old now. He never published another
thing after that paper. Not a word. When asked why, all he said was, âI have nothing more
to say.â Apparently he also invented the mic drop. Itâs been another 24 years since Shattuckâs
book. And my answer to all the questions asked by Shattuck, Quine, Gettier, and Plato is:
I donât know. And yeah, social media is nuts, but the other
day I was reading a thread by Simon DeDeo -- heâs a professor at Carnegie Mellon and
runs the Laboratory for Social Minds at The Santa Fe Institute. He was talking about knowledge
and justified true belief, and he said one reason he likes doing science with others
is because they can help him disprove something he believes more efficiently than he can himself.
He said that works best âbecause we need help in exploring the unknown. If you're walking
in the woods, you can either walk towards a landmark, or away. Walking *away*, for some
reason, seems to work better.â Thatâs what weâre doing, all the time.
Weâre identifying the known and exploring the unknown. We struggle with imperfect knowledge.
And whether itâs science, philosophy, cats or hot dogs, to get to where weâre going,
sometimes we just need to walk away. And as always, thanks for watching. So, Sheriff Cat. Do you arrest like humans
or do you arrest other cats? Do you arrest dogs? Like, how does this work.. H..Hold on.
Hello? Hey! You can watch more of Neil and I discussing
the boundaries of knowledge and science over on StarTalk. Make sure you subscribe to StarTalk
while youâre there. It is wonderful. Also, the summer Curiosity Box has dropped
and you can start thinking now by getting yours at CuriosityBox.com. Itâs made by
Vsauce and this is the subscription for THINKERS. So, basically, YOU. Bye.
Neil deGrasse Tyson agrees that hot dogs are sandwiches. Pack it up boys, the argument is over.