epistemology: knowledge, skepticism, and ignorance

Download Epistemology:  Knowledge, Skepticism, and Ignorance

Post on 22-Jan-2016

40 views

Category:

Documents

0 download

Embed Size (px)

DESCRIPTION

Epistemology: Knowledge, Skepticism, and Ignorance. Clark Wolf Director of Bioethics Iowa State University jwcwolf@iastate.edu. Argument for Analysis:. - PowerPoint PPT Presentation

TRANSCRIPT

  • Epistemology: Knowledge, Skepticism, and IgnoranceClark WolfDirector of Bioethics Iowa State University

    jwcwolf@iastate.edu

  • Argument for Analysis:Everything I believe is consistent with the hypothesis that I am being deceived by a powerful evil demon. But even a powerful evil demon could not convince me that I dont exist when in fact I do exist. For when I doubt my existence, I immediately realize that there must be something (or someone) doing the doubting. When I doubt whether the statement I exist is true, I immediately realize that it cannot be false, for the act of doubting must be done by someone: by an I who must exist. Even if I am deceived in everything else, I cannot be deceived cannot be wrong about my own existence. Thus, after everything has been most carefully weighed, it must finally be established that this pronouncement I am, I exist is necessarily true every time I utter it or conceive it in my mind. (p. 493.1)

  • Everything I believe is consistent with the hypothesis that I am being deceived by a powerful evil demon. But even a powerful evil demon could not convince me that I dont exist when in fact I do exist. For when I doubt my existence, I immediately realize that there must be something (or someone) doing the doubting. When I doubt whether the statement I exist is true, I immediately realize that it cannot be false, for the act of doubting must be done by someone: by an I who must exist. Even if I am deceived in everything else, I cannot be deceived cannot be wrong about my own existence. Thus, after everything has been most carefully weighed, it must finally be established that this pronouncement I am, I exist is necessarily true every time I utter it or conceive it in my mind. (p. 493.1)

    1) When I try to doubt that the statement I exist is true, I realize that there must be some subject (me) doing the doubting. 2) If there is a subject doing the doubting, that subject must exist. 3) Whenever I doubt the statement I exist, it is immediately evident that I exist.4) Conclusion: The statement I exist is self evidently true.

  • Argument for Analysis:Im obviously imperfect, full of doubts and false beliefs. But I have an idea of perfection, and this idea is itself perfect. Nothing imperfect could create something perfect, so this perfect idea cannot have come from me, it must have come to me from another source. But only a perfect source could cause a perfect idea. So there must be a perfect beingGod who is the cause of my perfect idea.

  • Im obviously imperfect, full of doubts and false beliefs. But I have an idea of perfection, and this idea is itself perfect. Nothing imperfect could create something perfect, so this perfect idea cannot have come from me, it must have come to me from another source. But only a perfect source could cause a perfect idea. So there must be a perfect beingGod who is the cause of my perfect idea.

    1) I have a perfect idea.2) Nothing perfect could come from something imperfect. 3) I am imperfect. 4) This perfect idea could not have come from me. (From 1,2,3)

    5) Only a perfect being could be the cause of a perfect idea. (A new claim, but interestingly related to premise 4.)6) There must be a perfect being. (From 1,5)7) If there is a perfect being, that being would be God. 8) Conclusion: God Exists. (From 6,7)

  • Argument for AnalysisMind and body are either the same substance, or they are different substances. If two things are identical, then they will have all the same properties. So if my mind and body are the same substance, they must have all properties in common. But I can doubt my bodys existence my body is dubitable. I cant doubt my minds existence my mind is indubitable. Therefore mind and body are different substances.

  • Mind and body are either the same substance, or they are different substances. If two things are identical, then they will have all the same properties. So if my mind and body are the same substance, they must have all properties in common. But I can doubt my bodys existence my body is dubitable. I cant doubt my minds existence my mind is indubitable. Therefore mind and body are different substances.

    1) Mind and body are either the same thing, or they are different substances. 2) If two things are identical, then they will have all the same properties. 3) So if my mind and body are the same substance, theyll have all properties in common. 4) But I can doubt my bodys existence my body is dubitable. 5) I cant doubt my minds existence my mind is indubitable. 6) Mind and body do not have all properties in common. 7) Therefore mind and body are different substances.

  • Argument for Analysis:According to Descartes, we cant know something unless we are so absolutely certain that it is true that we cant doubt it. But if we accepted this, we would be forced to conclude that we know nothing at all, or almost nothing. Its just wrong to say that we dont know something just because we can doubt that its true, or just because its possible that its false: this isnt what we mean by the term know. For example, when I say I know where I parked my bike, because I remember doing it. I dont mean to indicate that I cant possibly be wrong about where I parked my bike, even if it turns out that Im a brain in a vat. So to know something isnt to be certain about it. So the Cartesian analysis of knowledge doesnt capture what we typically mean by knowledge.

  • Argument for Analysis:1) According to Descartes, we cant know something unless we are so absolutely certain that it is true that we cant doubt it. 2) But if we accepted this, we would be forced to conclude that we know nothing at all, or almost nothing. 3) But we know more than the Cartesian view would support. 4) So to know something isnt to be certain about it. 5) Descartes was wrong to believe that certainty is necessary for knowledge.

  • SKEPTICISM: Sextus EmpiricusPlato distinguished knowledge from opinion, urging that we know only things we discover through reason.

    Aristotle and others call into question Platos claim that we know the things Plato thinks we know through reason.

    So what do we know?

  • SKEPTICISM: Sextus EmpiricusQuestion: What is knowledge?

    CLAIM: You dont know something unless you have good evidence that it is true.

    Question: Do you know that you are in a philosophy classroom in Ames Iowa on a cold March morning?

  • SKEPTICISM: Sextus EmpiricusThought Experiment:

    (1) Do you know that the world did not spring into existence four seconds ago.

    (2) Do you know that you are not a brain in a vat?

  • An Argument for Skepticism:

    1) You have no evidence that youre not a brain in a vat.2) If you have no evidence for X, then you dont know X. 3) Therefore, You dont know youre not a brain in a vat. 4) If you dont know that X is false, but your belief Y would be unsupported if X were true, then you dont know Y.5) Therefore, you dont know any of the things that depend on the fact that youre not a brain in a vat. 6) If youre a brain in a vat, then everything else you believe is false. 7) Therefore, you dont know any of those things.8) Therefore you dont know anything at all.

  • An Argument for Skepticism:

    1) You have no evidence that youre not a brain in a vat. (Is this true? What evidence might you offer?)2) If you have no evidence for X, then you dont know X. 3) Therefore, You dont know youre not a brain in a vat. 4) If you dont know that X is false, but your belief Y would be unsupported if X were true, then you dont know Y. (Is this a questionable premise?)5) Therefore, you dont know any of the things that depend on the fact that youre not a brain in a vat. 6) If youre a brain in a vat, then everything else you believe is false. 7) Therefore, you dont know any of those things.8) Therefore you dont know anything at all.

  • Skepticism:

    Skepticism: We do not have knowledge of anything at all.

  • Epistemology: Theory of KnowledgeWhat is knowledge? What is it to know something?What does it mean to say that a belief is justified?What can we know?

    We might start by listing the things we believe:

  • Knowledge and BeliefWe have a vast collection of beliefs, and some of them are false: Some people believe that astrology can inform us about our futures. mind is constituted by the physical operation of the brain. mind is soul, an entity separate from brain activity that will survive the death or our bodies.the universe is ultimately describable in terms of physical laws.a full description of the universe will include magic and super-natural entities.aliens from outer space are in contact with human beings. human beings are the product of natural evolutionary selection. there is a God who created everything and who cares about us. human beings will make settlements on Mars. human beings are more likely, in the next millenium, to deplete the earth of its resources and destroy the ecosystems on which we depend for our lives. Sifting and sorting: We dont agree on all of these (at least, its unlikely that we do.) Those beliefs about which we're less certain are less likely to count as knowledge than those we're more certain of. Are there any beliefs of which we are absolutely certain?

  • Knowledge and BeliefWe believe many things.Not all of the things we believe are things we know.

    Among the things I believe, which are the things I know?

    Sextus? Descartes?

  • Knowledge and BeliefAmong the things I believe, which are the things I know?

    Hypothesis: The things I know are the beliefs that are true.

    Problem: What if I have true beliefs by accident or for bad reasons?

  • Knowledge: Platoss AnalysisP