Brain in the vat; knowledge, skepticism

1/23/09 Philosophy Knowledge Epistemology: theory of knowledge The sense of knowledge We use the word ?know? in different senses, and philosophers are interested in a specific sense of knowledge * *Propositional knowledge Proposition = sentence, but not quite the same Sentence is tied to a particular language ?the lamb is white? Can be said in another language Prop def = the meaning of the sentence, different languages for same sentence making a proposition When you have this, you are relating yourself in a certain way to a proposition ?I know that [water freezes at 32 degrees f]? [proposition] Know can be substituted with wish, believe, hope, etc. What makes this sentence true? What is knowledge? We believe water freezes at 32 degrees, can we know something without believing it? What do you need: To know something you have to believe it The belief has to be about something that is true Beliefs can be formed on unreliable things (horoscopes, hallucinations) ? there needs to be a justification for having a belief. Even if you do fail a test that your horoscope says you will, it could just be chance that it turned out to be true What?s missing is a guarantee of this Justification elevates a true belief to the status of something you know If it is false that water freezes at 32 degrees, I might think I know that, but I don?t really know it To know something it must be true and you must believe it ?This morning I saw Richard Nixon walking across campus? He is dead thus you could not have seen him Might have thought you saw him but not true See implies truth of what you saw ? I have thus said something false Different standards of justification that people might demand If a doctor tells me I have a rare disease and I have only two months to live, I want to know how certain the doctor is If 50 percent right then the doctor doesn?t know. He believes it but it?s not knowledge. Pollock creates standards he offers a skeptical argument Knowledge by acquaintance Familiarity with something ?I know Philadelphia? ?I know chancellor Martin? Know how (skill) Know how to play the violin = develop skill or talent Skepticism Different than doubt In the form Pollock presents it is worse than doubt Robs you of things you know that might remove the doubt No fixed point to help you remove the disbelief you are having A brain in the vat Think of the brain as a wire from eyes to the brain, etc. Stretch wires, take brain out of the head and put it in a solution, remove the wires from sensory organ and hook them up to a computer that inputs into the brain sensory signals these organs would transmit if they were connected Everything is thus artificial, just a stimulation of the brain in a certain way It is logically possible ? no incoherency (nothing in definition of the brain that would make it logically impossible Is it physically possible? Maybe ? would the laws of nature permit this? Can a computer be hooked up and replicate stimulation? Pollock is describing something logically possible ? even if it is strange why should we take it seriously? (thought experiment) What does it show us? Arguments we might derive from his thought experiment Knowledge requires certainty But the possibility we are brains in vats shows that we can never be certain therefore, we cannot have knowledge given the possibility we are all brains in vats, is that enough reason to throw into doubt all that we thought we are certain of things we can be uncertain if we have a brain in a vat if sensory things are real ? can?t be sure triangle has three sides: senses don?t tell us this we get it some other way ? can be sure this is capital ? can be sure if fiddles with your memory too ? margot said they already removed his brain three months ago if he reads (from the computer) carson city is the capital of nevada, may be false some beliefs he has from sensory objects come under doubt as well maybe wife has died but they keep feeding him sensory information of her Doubt Doubt whether your telephone works after your friend says he will call and it has been an hour past that Ways to diffuse doubt Check calendar: said tomorrow not today, diffuses doubt about whether telephone is working by showing that your belief is false The belief your friend would call today was false and that is why your phone has not rung Realize that you have the ringer turned off (not that your phone is broken, you just have it off) These explain away a situation that was creating doubt in you, that is why it?s not ringing You remove your doubt by appealing to some other kinds of facts (things you know) Fulcrum put lever over something you know and pry away the doubt Thought experiments Experiment you can do but not really do ? can only be done in your thoughts Doing the experiment in your thoughts should tell you something significant Why use them? To describe a situation which will help you focus in on just what is relevant to the matter at hand Real world is full of distractions: thinking of real life cases will only confuse what you are trying to figure out Ex: should I be a vegetarian? Is it okay to kill animals? What is wrong with killing animals? ? might do thought experiment Suppose I believe animals don?t feel pain, would it still be okay to kill animals (don?t really know if animals feel pain, or if its wrong to kill them b/c they feel pain) Imagine animal that can?t feel pain and imagine killing it, and say yes its okay then. From this you can derive that killing animals Lettuce that feels pain, humans that don?t :consider impossibilities able to refine and distill what is the true issue (why is it wrong to kill an animal and eat it) Very useful device ? Logical possibility We know some things are possible because they are actual Get up in the morning to go to class, b/c do it actually possible Some things are possible even if they never happen Possible the eagles would have beaten the cardinals; didn?t happen but possible Possible It could go above freezing today even if it doesn?t happen Possible things that can?t happen given the laws of nature I want to be able to fly ? Logically possible you could fly but arms don?t allow it To assess if it is logically possible need to test it If there is no inconsistency or incoherency then there is no logically impossible To find physically possible or impossible need laws of nature Triangle has three sides and angles Concept of a triangle is something of three sides Could a triangle have four sides No because by its definition it has three sides. Something cannot have only three sides and four sides at the same time Married bachelor? Bachelor is defined as unmarried, thus it is logically impossible that you can be married