Lesson video

Hello there.

My name is Mr. Robertson.

Thank you so much for joining me in this RE lesson today.

Today's lesson is in our exciting unit Personhood: what does it mean to be alive?

And the title of today's lesson is "Consciousness: are we just brains in a vat?

" What an amazing title, hey?

And we're going to be thinking all about this big idea in philosophy of what is consciousness and how do we know we are who we think we are?

Let's find out.

So by the end of this lesson, you will be able to evaluate different ideas of consciousness and how humans perceive reality.

In this lesson, we have four keywords.

Our first word is consciousness, and that means the state of being aware or able to think about one's existence, thoughts, and surroundings.

We've also got the word dualism, which means both physical and non-physical things exist.

The mind or consciousness is non-physical and separate from the body.

Physicalism is everything that exists is physical, including the mind or consciousness.

Rene Descartes was a French philosopher who lived from 1596 to 1650 and who built his philosophy by doubting everything except his own thinking.

A lot of these words I know sound really complicated, but as we go through, you're going to have these concepts explained, and hopefully by the end of the lesson you will be able to understand and use them.

So there are two parts in this lesson.

The first part of the lesson, we're going to be thinking about skepticism and the self.

So philosophers are people who use logic to explore ultimate questions about existence, knowledge, ethics, and reality.

And whether you are religious or non-religious worldview, you can use philosophy as a tool to investigate questions such as what makes us who we are.

Now, one way philosophers investigate ultimate questions is through the use of thought experiments, which test ideas in hypothetical contexts.

And we're going to be looking at some thought experiments today.

Let's start with a broad question.

In a video game, if you've played video games, the characters think the world they live in is real.

They're inhabiting this world, whatever it is.

Maybe it's a battlefield, maybe it's a creepy house.

If you lived inside a game, how would you know it was a simulation?

How would you know that what you thought was real wasn't actually real, but was in fact a constructed game?

It's an interesting and tricky question, isn't it?

We don't actually know the world around us whether it is real or not, and that's one of the really big questions we're going to be looking at today.

So let's learn first of all about this chap.

This is Rene Descartes, and he's one of the most influential philosophers in the Western tradition.

He used thought experiments to engage in skepticism.

Now, philosophy involves asking questions about how we can know what is real.

And Descartes was driven by a quest to find knowledge.

He realized that many of the things he believed could be doubted.

For example, our senses can sometimes deceive us.

Sometimes we can have dreams which feel very, very like real life, and we wake up and we're like, "Oh, I was in a dream.

" And even mathematics could be false.

He had this idea of a demon which was deceiving him at every turn and making him think what was real wasn't real.

So his big question was, how can we even know what is real?

And this type of doubting of everything is called skepticism.

So why did Descartes engage in radical doubt?

A, to show that dreams are more real than waking life.

B, to prove that the senses are always trustworthy.

C, to find knowledge that could not be doubted.

Think about what we've just been learning.

You might want to pause the video and have a think.

Excellent.

He was looking to find knowledge that could not be doubted.

Brilliant if you got that right.

Now, the philosopher Hilary Putnam developed a modern version of Descartes' evil demon hypothesis, and she introduces a famous thought experiment called the brain in a vat.

Now, I want you to imagine that a brain has been removed from its body and it's been put in a vat, a bucket of nutrients which keep it alive.

And this brain is then connected to a computer.

The computer generates signals identical to those produced by our senses.

The brain believes that it's living a normal life, but in reality, every experience is artificially produced by the computer.

You can see in the diagram there, there is the brain in the vat and the computer is generating experience which makes the brain think that it's in a body and it's walking along.

But actually it's not, is it?

It's in a vat, but the brain doesn't know this.

The brain thinks it's walking around because the brain is being fed these systems by a computer.

So how on earth do we know that we are not brains in a vat?

How do we know that the existence around us is really real and that we're not being given these as signals by a supercomputer?

The point of this thought experiment is to ask whether we can rule out the possibility of complete deception.

If we can't prove that we are not brains in a vat, we can't really know anything about the external world.

If our thoughts and feelings are generated by a computer, then we could also question what we mean when we talk about the self.

The important thing about Putnam's theory is it forces us to confront the possibility that our existence, our mind, may be an illusion.

So Putnam's brain in a vat thought experiment is designed to encourage people to think about what they can know.

If a computer could fool all your senses, how could you tell the difference between reality and illusion?

If your thoughts and feelings were generated by a computer, would you still be you?

Can we ever be completely certain that the external world exists?

These are really massive questions, aren't they?

I wonder what you think about some of the answers to these questions.

Let's talk to Zara.

Zara is an atheist and she studied philosophy at university, and she's explaining about the brain in a vat thought experiment and how it's affected her.

She says, "I don't think it's possible to prove we are not a brain in a vat, because to do so, we would have to rely on our senses, which could be simulated.

This thought experiment reminds me to think more carefully before accepting ideas because I can't prove the world is real.

It also makes me question the self.

Am I just my thoughts or do I need a real body and world to be me?

" So for Zara, she thinks it's a really useful thought experiment because it helps to make her question things rather than just take things on face value.

Layla's a Muslim who also studied philosophy at university, and she thinks a little bit about this explanation of the brain in a vat thought experiment.

She says, "I agree it's impossible to prove we're not a brain in a vat, but I think the best hypothesis is that we are not, since that explanation is the one that works in practice.

Even with uncertainty, I still trust my experiences and see myself as someone who exists in the world.

Rather than questioning whether I'm just thoughts, I ask how my body, actions, and relationships make me who I am.

" So Layla's saying, well, I can't prove I'm not a brain in a vat, but actually my body, my thoughts tell me that I'm not.

I feel like the world around me feels real to me.

So okay, I'm uncertain about it, I can't prove it, but actually that's not that important to me.

The most important thing is about my own body, my actions, the relationships.

How do they make me who I am?

So Layla accepts the uncertainty, but she's prepared to trust what she can see around her.

I wonder which of those two views feels quite closest to yours?

Do you share Zara's uncertainty and doubt or do you go more for that trusting approach of Layla?

Let's just check our understanding so far.

What's the missing word here?

Hilary Putnam introduced the brain in a vat thought experiment in which a brain is removed from its body and connected to a what that simulates all sensory experiences.

What was the brain connected to, can we remember?

Excellent.

It was a computer.

Well done if you got that right.

Okay, so that's a really big thought experiment we've been introduced to.

Let's think about this.

I'd like you to read Zara and Layla's questions, and then I'd like you to discuss with someone else how engaging in the thought experiment might affect the way someone understands the self.

Together, decide whose responses most aligns with your own and be ready to report back.

So Zara says, "Am I just my thoughts, or do I need a real body and world to be me?

" Layla says, "How do my body, actions, and relationships make me who I am?

" Can you make a link between what Zara's saying and the idea of a brains in the vat thought experiment, how that might make them understand themselves?

Zara's asking a question and Layla's asking a question.

Which one of those responses most links to how you think?

Go away, work with someone else, be ready to report back.

Wow, some brilliant ideas.

Amazing engagement there, philosophers.

So you might have said something like, Zara's question is about being skeptical.

It makes you wonder if your identity is just in your mind or whether there is a body or external world necessary for being yourself.

But Layla assumes the world is real.

She's more interested in how your connections and relationships shape identity.

One of the things about this thought experiment is it pushes people to think more carefully about what the self is.

Some people like Zara focus just on the mind as being the most important things, while other people like Layla stress the importance of bodies and relationships as well.

Now, you might have had a different answers to this, but you might have said something like, Layla's response most aligns with our own, because even if we can't prove the world is real, the best explanation is that it is.

This means our self is shaped not just by our thoughts, but by the things we do and our relationships in the real world.

Brilliant if you've managed to think about these big ideas.

Okay, in the next part of the lesson, we're going to be thinking about different theories of consciousness.

So Descartes engaged in thought experiments to find out what he could know for certain.

We said that for philosophers, a thought experiment is a really useful way of trying to figure out big questions.

And although he doubted everything, eventually he realized one thing was certain.

He said, "I think, therefore I am.

" So basically, because he could think, he must exist.

Because he could sit in his chair and think about himself and picture himself, he must exist.

So for a long time, it was assumed that consciousness was not physical.

This idea is known as dualism.

And this idea has been around since ancient times all the way through to the modern day.

Many worldviews see consciousness as non-physical.

In other words, that there's our bodies and we are a physical thing that can touch and feel, but the bits that make us ourselves are not physical.

They're somewhere inside us, but they're not actually physical.

You can't cut out a piece of the body and say, this is consciousness, this is the self.

So this idea of dualism splits the mind from the body, and it's a really common worldview in the West particularly.

In the early 20th century, we had this new idea called physicalism, and this started to see consciousness actually as physical rather than non-physical.

So let's explore that a bit further.

Although he could not be certain he had a body, Descartes was certain that he was a thinking thing, and this led him to develop the theory of dualism.

Two kinds of things exist: non-physical and physical.

Descartes defined the mind or consciousness as non-physical.

You can't see it, touch it, and find it.

Whereas the body and the brain are physical.

We can see the brain, but we can't necessarily see consciousness.

And this idea of dualism fit into the traditional Christian worldview.

So Hannah is a Roman Catholic and she's talking about how this idea impacts her.

She says, "I try to live from the inside out.

I don't assume the world will make sense on its own.

I'd begin with what I know for certain, that I'm a thinking being.

It's the foundation of who I am.

My body might be tired or anxious, but my mind is still mine.

As a Christian, I trust that God who gave me this mind guides my understanding.

" So for Hannah, the mind is a non-physical thing, which she believes that's inspired by God and that fits her worldview.

Let's just check this idea of dualism then.

A, the mind is physical and the body is non-physical.

B, the mind is non-physical and the body is physical.

C, only the mind exists.

D, only the body exists.

Which one of those makes most sense?

Think about what Descartes was saying.

Excellent.

It's B, isn't it?

It's the mind is non-physical and the body is physical.

The self, the consciousness, we can't see that, that isn't physical, but our bodies and brains are physical.

In the 20th century, some philosophers began to argue that it's a mistake to categorize the mind as separate from the body.

Modern understanding of the brain and nervous system provide physical explanations to questions about consciousness, for example, about how the brain creates what we see, how memories form, and how injuries can change behavior.

If people have a brain injury, their personalities can change, which suggests some scientists and philosophers to say, well, actually, consciousness is a physical thing then, it's not a completely non-physical thing.

The philosopher JJC Smart proposed one of the physicalist theories, which is known as the mind-brain type identity theory.

He says that our mind or consciousness is made up of mental states.

So when we experience something like being in love, that is a brain state.

Or when we feel anger, that's a brain state.

In the same way that we say water is the same as H2O.

We can see a physical thing called water, but we know it's made up of hydrogen and carbon in the same way that what we experience is actually just a state in our brain.

It's our brain creating that idea of love rather than something completely separate from our bodies.

And when we feel in love, when we fall in love, we feel it in our bodies as well as our minds.

We might have a racing pulse.

We might feel scared or worried or excited.

So often stuff in our brains, we feel it in our bodies as well, which suggests that our bodies and minds are much more connected and not separate.

Physicalist theories like this often fit into an atheist worldview.

Neil is a humanist and he's talking about how being a physicalist impacts him.

He says, "I see my consciousness as something my brain produces.

When I'm anxious or happy, it's my brain responding to the world.

I'm less reactive with others because I assume their behavior has real-world causes too.

When something feels good, it actually feels more impressive because it's amazing that a physical brain can produce experiences that rich.

" So he feels like this stuff is experiencing it in our brains, but we feel it in our bodies as well.

Let's just check our understanding so far.

True or false?

Modern neuroscience offers physical explanations for many aspects of how the brain produces consciousness.

Is that true or false?

Think about what we've just been thinking about.

Ideas of love, for example.

Excellent.

It's true, isn't it?

Because neurosciences explains many brain processes linked to consciousness, like vision and memory.

But not all modern-day philosophers think that consciousness can be fully explained physically.

David Chalmers is a philosopher who defends a new form of dualism.

He says there are two problems of consciousness.

The easy problem is explaining how the brain works and controls behavior.

The hard problem is explaining why it feels like something to see, remember, or feel emotion at all.

Chalmers has created a new thought experiment to support his ideas.

This is his thought experiment.

He says, imagine a philosophical zombie.

This is a being who is physically identical you in every way.

Their body, brain, and behavior are exactly the same as you.

If they drink a cup of hot chocolate, they smile, say it tastes good.

Mm, what delicious hot chocolate.

If you tell a joke, they laugh.

But inside they have no inner conscious at all.

No warmth, no pleasure, no inner glow.

If you can imagine such a being and they're physically the same as you, this shows that consciousness or the mind is something extra and not physical.

That means dualism must be true.

So this thought experiment is saying is, can you imagine a creature like you who could do all the same things as you, but it wouldn't feel it inside?

It would just be saying the words.

If you can, he's saying, that means there is something extra to being you, which is not simply physical.

Chalmers' philosophical zombie thought experiment is designed to show that consciousness is not physical.

If a philosophical zombie could act exactly like you, but had no inner feelings, does that mean that consciousness is something beyond the physical body and brain?

If consciousness is non-physical, what does that suggest about the mind and how it relates to the body?

What would it mean for science if consciousness cannot be explained just by studying the brain?

So these are really, really big questions to ask, and this might be quite hard, but I think what we need to know here is that there's not a set, agreed idea here.

There are lots of theories about consciousness, and scientists and philosophers don't know the answer yet.

This idea of dualism can fit with both religious and non-religious worldviews.

Toby is spiritual, but he is not religious.

He's been thinking about the philosophical zombie thought experiment.

He says, "I think Chalmers is right, and we can imagine philosophical zombies who are physically identical to us, but who have no inner experience.

This means consciousness is more than the physical brain.

Our inner lives make us valuable and meaningful, something we should honor in one another.

" So Toby's saying that he agrees with this experiment and it shows that consciousness, the bits that make us who we are, is more than just the brain.

It means we have something inside us which makes us valuable and meaningful.

And therefore he said we should honor and care for each other because of the fact we all have that inner core.

Let's just check our understanding here.

What does David Chalmers say about consciousness?

A, it can be fully explained by physical processes in the brain.

B, it involves something non-physical and cannot be fully explained physically.

C, it doesn't exist.

D, it's an illusion created by the brain.

Pause the video and have a think.

Excellent.

It's B, isn't it?

It involves something non-physical and it cannot be fully explained physically.

That's the idea of the philosophical zombie, something identical to you, but without that inner core, that inner consciousness.

Okay, I've got a task for you to think about this now.

And I've got some statements for you, and I'd like you to think, do these statements express a dualist, i.

e.

the mind and body are separate from each other, there is a physical body and then there's a non-physical mind inside, or a physicalist view, which says actually they're all one, and what we think of as ourselves can be explained by states in the brain.

Consciousness can be explained by the brain and nervous system.

Is that dualist or physicalist?

Consciousness is something extra beyond the physical, dualist or physicalist.

Mental states are the same as brain states.

The body and mind are separate.

The mind is a non-physical thing.

Thoughts and feelings are produced by physical processes.

Go through each of those and put a tick whether you think it's a dualist or physicalist idea.

Okay, so you might have said that consciousness can be explained by the brain and nervous system is a physicalist, but consciousness being something extra beyond the physical is dualist, because dualists think that the mind and body are separate.

A physicalist would say mental states are the same as brain states, whereas a dualist would say the body and mind are separate.

A dualist would say the mind is a non-physical thing because it's not inside, it's in something separate.

Whereas a physicalist would say thoughts and feelings are produced by physical processes.

Brilliant if you managed to get that right.

Second thing I'd like you to think about is, are you a dualist or a physicalist?

What do you think your ideas are?

Do you think that like a dualist, there is a body, but a mind is something different and separate and the sense of you is separate?

Or are you more of a physicalist, where you say, well, it's all one thing, and the things that we experience are produced in the brain?

You could use some of these sentence starters to help you.

I'm a dualist or a physicalist because I think.

The strongest argument for my view is.

I'm convinced by this argument because.

Someone who disagreed with me might say.

I think this is a weak argument because.

Good luck, everyone.

Looking forward to seeing your ideas.

So you might have said things like, I'm a physicalist because I think our thoughts, memories, emotions depends on what happens in the brain.

The strongest argument for my view is that changes to the brain can change behavior, personality, and experience.

I'm convinced by this argument because it fits with what we know from modern neuroscience.

Someone who disagreed with me might say that physical explanations cannot describe what it feels like to be consciousness.

I think this is a weak argument because it doesn't show that consciousness is non-physical.

It only shows we don't yet understand everything about the brain.

Really interested to know whether you felt you were either a dualist or a physicalist.

And if you didn't know, don't worry, because this is really complicated stuff.

It's just to get you thinking about the idea that there are lots of different ways of looking at our brain and our consciousness.

And scientists and philosophers don't agree about this, and they try different ways to think this through, like thought experiments or thinking about what we already know about the brain.

But brilliant for having a go.

Well done.

So let's summarize what we've thought about today.

Descartes used radical skepticism to test whether anything could be certain.

He concluded that thinking proved his existence and said, "I think, therefore I am.

" Hilary Putnam proposed the brain in a vat thought experiment, showing we might not know anything outside reality.

Dualists argue that consciousness is non-physical and defines human identity.

Physicalists, such as JJC Smart, defend mind-brain identity theory, which says that mental states are brain states.

Amazing thinking with a really complicated subject today, and I look forward to seeing you in another lesson soon.

Thank you.