Three more thought experiments

I am a big fan of though experiments and in the past I have done a couple of posts about them: 1, 2. Here are three more:


Adventures in time travel

My first experiment actually comes from one of my students. Imagine you can travel back in time to the municipality of Braunau am Inn in Austria.  It is October 1889 and before you a young baby, Adolf Hitler, is sleeping peacefully. Would you pick up a pillow and quietly smother the infant. There are those who would make he case that murder is always wrong, especially if the victim is a baby. However, you would certainly save the world a lot of grief. Or would you? If we replayed Hitler’s life again would the result be exactly the same? Maybe worse things would have happened if Hitler had never been born. I will come back to Hitler soon but now I want to look at time travel itself.

Time travel presents a lot of hard questions. Indeed, it is the subject of a famous thought experiment known as The Grandfather Paradox. It was raised by René Barjavel in his 1943 book Le Voyageur Imprudent. In it Barjavel proposes that time travel is impossible. It goes like this:

Let’s say you travel back in and kill your biological grandfather before he has met your grandmother. Consequently your parents, and by extension you yourself would never been conceived. This would imply that you could not have travelled back in time after all, which means your grandfather would still be alive, and you would have been conceived allowing you to travel back in time and kill your grandfather. Each possibility seems to imply its own negation, creating a logical paradox. Despite the name this paradox is not exclusively about grandfathers. Rather it makes the case any kind of time travel is logically impossible. You could use scientific knowledge to invent a time machine, then go back in time and impede a scientist’s work that would eventually lead to the very information that you used to invent the time machine. And there is a specific variation on the Grandfather Paradox, autoinfanticide, in which you go back in time and kill yourself as a baby. This, of course, is a rather morbid, and potentially dangerous, thing to do. So please don’t try it at home.

So let’s go back to Herr Hitler because this kind of scenario is affected by the Grandfather Paradox. You actually manage to kill him. And although this is highly debateable, WWII is averted and millions of lives are saved. You are now faced with a temporal paradox: without the holocaust and the carnage of 1939-45, you will have no reason to go back in time and kill Hitler, so you don’t. This means Hitler will live, and millions will die in the world war and extermination camps. Consequently you will have to go back in time and kill Hitler… you get the idea.

Thomas Nagel’s bats

In 1974 philosopher Thomas Nagel published a famous article in Philosophical Review – What Is it Like to Be a Bat?  You may be thinking that Nagel had taken too much  LSD, but it is actually a fascinating experiment. Nagel argued that it is impossible for us to know what a bat feels. He was not referring to the sensations of being short-sighted, eating bugs, hanging upside-down in a cave with our mates. That would be describing what it would be like for US  to be bats.

Nagel was looking at how bats perceive the world. First we need to look at their   language, which consists of squeaks and cries. Nagel wasn’t interested in the public language they use to communicate with other bats. What he was interested in is their inner language. As far as we know bats do not possess an inner language that uses linguistic concepts. Secondly there is echolocation, those squeaks they emit work like radar, letting them know the location of objects. Humans have no comparable sensual experience. How can we possibly imagine what this is like?  What Nagel was arguing was that their sensory inputs give them a subjective experience that we are incapable of imagining.

The purpose of Nagel’s piece was not to look at the inner lives of bats, fascinating though that may be.  Nagel was using bats as a way of meditating on the mind-body problem. This is one of those intractable problems that philosophers love and the relationship between mind and brain has exercised them for centuries. How can something physical give rise to the subjective experiences of minds. Nagel wants to say that we may be good at describing how neurons fire off, but we are incapable of explaining consciousness itself. Science is good at describing things objectively. But Nagel believes there is something subjective that does not lend itself easily to scientific analysis. Nagel argues that consciousness has an essentially subjective character, a what it is like aspect:

It seems unlikely that any physical theory of mind can be contemplated until more thought has been given to the general problem of subjective and objective.”

He is not anti-science nor is he a dualist, but he is anti-reductionist. He believes that we need to appreciate the fact that the whole is perhaps greater than the sum of its parts. I am a bit of a pessimist as to whether we’ll ever be able to understand such a fundamental question  Maybe our mind is just too limited a tool and the question too difficult.

A Picasso on the beach

This one I got from Julian Baggini’s The Pig That Wants To Be Eaten:

Roy looked down from the cliffs at the man drawing in the sand. The picture that started to emerge startled him. It was an extraordinary face, not realistically rendered, but seemingly viewed from many angles at once. In fact, it looked much like a Picasso. As soon as the thought entered his mind, his heart stopped. He lifted his binoculars to his eyes, which he then felt compelled to rub. The man on the beach was Picasso.. Roy’s pulse raced. He walked this route every day, and he knew that very soon the tide would sweep in and wash away a genuine Picasso original. Somehow, he had to try to save it. But how? Trying to hold back the sea was futile. Nor was there any way to take a cast of the sand, even if he had had the time he was actually so short of. Perhaps he could run back home for his camera. But that would at best preserve a record of the work, not the picture itself. And if he did try this, by the time he got back, the image would probably have been erased by the ocean. Perhaps then he should simply enjoy this private view as long as it lasted. As he stood watching, he didn’t know whether to smile or cry.

The basis for Baggini’s experiment was a short story by Ray Bradbury, In a Season of Calm Weather. Its main character George Smith is taking a holiday in France. Smith is captivated by the work of Pablo Picasso. When he learns that the artist is visiting friends in a small fishing town only a few miles away, he is ecstatic. He secretly dreams of meeting the great artist and talking with him. One day late in the afternoon he is alone on the beach and he goes for a final walk. He spies an old man walking along the darkening shore, all alone. The man picks up a stick from the ground and begins to draw. Smith approaches him and on seeing the drawings he realises that this old man  is Picasso and he begins to tremble and he is incapable of articulating a word. It is then that the awful truth dawns on him – the tide is about to come in, and these works of art will be lost forever. He doesn’t have time to go back to the hotel to get his camera. There is no point trying to pick up a shovel to save a chunk of the crumbling sand? And it would be futile to find a workman to make a mould with plaster of Paris. As Picasso walks away I’ll let Bradbury take up the story:

George Smith stood looking after him. After a full minute he did the only thing he could possibly do. He started at the beginning of the fantastic frieze of satyrs and fauns and wine-dipped maidens and prancing unicorns and piping youths and he walked slowly along the shore. He walked a long way, looking down at the free-running bacchanal. And when he came to the end of the animals and men he turned around and started back in the other direction, just staring down as if he had lost something and did not quite know where to find it. He kept on doing this until there was no more light in the sky or on the sand to see by.

He then goes back to the hotel, but he doesn’t tell his wife of his encounter with genius.

There are a number of themes in this story. We have the fleeting nature of beauty, sometimes we try to capture it, but the best thing is to enjoy the moment. I often think about this when looking at a work of art. This summer when we were at the Courtauld Institute in London they were filming the visitors as they looked at the paintings. It would be interesting to discover the results of the experiment.

Can a work of time last for ever? We can make a distinction between the performative and the plastic. When you see a ballet or a concert you realise that you have to accept that what you are seeing or listening has to be appreciated in the moment. You can watch a recording, but you will never recreate the exact experience. But the plastic arts are not guarantee of permanence either. I have always been intrigued by ice sculptures. Why would someone put so much time and effort into something so ephemeral? Even a painting is not immune to this as pigments age.

Baggini argues that our desire to preserve art is a form of denial about our own mortality. Artists are seeking a form of proxy immortality through their oeuvre. It reminds me of the Shelley poem Ozymandias which I featured a few weeks ago in a post about architecture. Its central theme, the inevitable decline of everything that the Egyptians thought they had created for posterity, is pertinent to this discussion. There is something very poignant about a post-human world in which works of art remain but with no one to appreciate them. If we accept that nothing is immortal, we should be able to see that the value of both art and life itself is to be found: in experiencing them.

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