24 entries
Thought Experiments
Imagined scenarios built to test an idea, alongside a few real experiments, from Libet's timing studies to split-brain surgery, that philosophers still argue about. Each one reveals something about what we already believe.
- I.Does your brain decide before you do?In 1983 a neuroscientist found brain activity that began before people felt they had decided to move. What it shows about free will is still fought over.Free will · Intermediate
- II.Could you be responsible without any alternatives?A hidden device would have forced your choice, but it never activates, because you choose that way on your own. Were you free?Free will · Deep
- III.Could a perfect mind predict everything?Imagine an intellect that knows the position and motion of every particle. In a deterministic universe, nothing would be uncertain to it, and the future would be as plain as the past.Free will · Intermediate
- IV.What is it like to be a bat?A bat perceives the world by echolocation. However much we learn about its brain, we may never know what that is like from the inside.Mind · Intermediate
- V.Mary's roomA scientist who knows every physical fact about colour has never seen red. When she finally does, does she learn something new?Mind · Intermediate
- VI.Could there be a zombie you?Imagine a being physically identical to you, atom for atom, who acts exactly as you do but feels nothing. If that is even possible, consciousness is something extra.Mind · Deep
- VII.The Chinese roomA man in a room follows a rulebook to answer questions in Chinese perfectly, without understanding a word. Is that all a computer ever does?Mind · Intermediate
- VIII.Are you a brain in a vat?A brain kept alive in a vat, wired to a computer that feeds it a perfect simulation of life. From the inside, it would seem exactly like your life.Knowledge · Intermediate
- IX.Two minds in one head?When surgeons cut the connection between the brain's hemispheres, each side began to act as if it had a mind of its own.Identity · Intermediate
- X.The Ship of TheseusReplace a ship's planks one at a time until none of the originals remain. Is it the same ship? And if someone builds a second ship from the old planks, which one is the original?Identity · Introductory
- XI.Would you step into the teleporter?It scans you, destroys your body, and builds a perfect copy on Mars a moment later. The copy wakes up remembering stepping in. Did you travel, or did you die?Identity · Intermediate
- XII.Could you upload your mind?If every connection in your brain were scanned and run on a computer, would the program be you, a copy of you, or no one at all?Identity · Intermediate
- XIII.Are we living in a simulation?If advanced civilisations can run vast numbers of simulated worlds, simulated minds would vastly outnumber real ones. So which are you more likely to be?Reality · Intermediate
- XIV.Are you a Boltzmann brain?Given enough time, random fluctuations could assemble a single brain with your memories out of chaos. In some cosmologies, such brains vastly outnumber real observers.Reality · Deep
- XV.Plato's cavePrisoners chained in a cave see only shadows on a wall and take them for reality. What happens when one of them is freed and sees the sun?Knowledge · Introductory
- XVI.What if a demon deceived you about everything?Descartes imagined a powerful demon devoted to deceiving him in everything. Searching for one thing the demon could not fake, he found it: the fact that he was thinking.Knowledge · Introductory
- XVII.The trolley problemA runaway trolley will kill five people unless you divert it onto a track where it will kill one. Most people pull the lever. Change one detail, and most people refuse.Ethics · Introductory
- XVIII.Would you plug into the experience machine?A machine can give you any experiences you want, indistinguishable from reality, for the rest of your life. Would you plug in?Ethics · Introductory
- XIX.Would you be good if no one could see?A shepherd finds a ring that makes him invisible. He uses it to seduce a queen, kill a king and take the throne. Would anyone do differently?Ethics · Introductory
- XX.The drowning childYou would ruin your expensive shoes to save a child drowning in front of you. Then why not spend the same money to save a child dying far away?Ethics · Introductory
- XXI.The veil of ignoranceDesign a society without knowing who you will be in it: rich or poor, healthy or sick, which gender, which race. What rules would you choose?Ethics · Intermediate
- XXII.Would you live your life again, forever?A demon tells you that you will live this exact life again, every moment, infinitely many times. Would you curse him, or call it the most divine thing you ever heard?Meaning · Intermediate
- XXIII.Must we imagine Sisyphus happy?Condemned by the gods to roll a boulder uphill forever, only to watch it roll back down. Camus saw in him an image of every human life, and concluded that he could be happy.Meaning · Introductory
- XXIV.Is knowledge just justified true belief?For two thousand years, philosophers said knowledge is a true belief you have good reason for. In 1963, a three-page paper showed that you can have all three and still not know.Knowledge · Intermediate