Philosophy UNIT 1

• P Necessary for Q


  Q is true only if P is true. (if Q, then P)
• P Sufficient for Q

  Q is true if P is true. (if P, then Q)
• Necessary and Sufficient for Q


  P if and only if Q. ('P iff Q')
• Example


  • x is human is necessary for x is a man
  • x is red is sufficient for x is colored
• If P is necessary for Q, then Q is sufficient for P
• Epistemology


  Study of knowledge, belief, evidence, justification, rationality, and inquiry
• Descartes


  French philosopher, mathematician, scientist. Founder of modern philosophy
• Skepticism


  • Many beliefs uncertain. What can we be certain of?
  • Doubt as much as possible to find undoubtable truths
• Descartes' "Meditation 1" explores skepticism and foundational beliefs
• Questioning Certainty


  • Can we doubt perceptions, existence, reality?
  • Skeptical hypotheses: Evil demon, Brain in a vat
  • Can we doubt everything? (Except cogito, ergo sum.)
• Cogito, ergo sum


  • "I think, therefore I am."
  • Foundational belief in Descartes' skepticism
  • Certainty in one's own existence as a thinking being
• Skeptical Hypothesis


  • Radical hypotheses challenging ordinary beliefs
  • Debate on knowing or justifying their falsehood
  • Skepticism raises questions about knowledge and certainty
• Closure Principle


  • If P entails Q, and you know P, then you're in a position to know Q
  • Principle of epistemic closure
• • Skeptical Argument: If you know you have hands, you can know you're not a brain in a vat
  • Can't know you're not a brain in a vat
  • Conclusion: You hardly know anything!
• Descartes's "Meditations" is a philosophical work aimed at demonstrating the existence of God and the distinction between the soul and the body
• Meditation I explores radical doubt by considering the possibility of being deceived by an evil demon or dreaming, leading Descartes to conclude that most of his beliefs are dubitable
• Meditation II marks Descartes' discovery of something indubitable: his own existence as a thinking being
• Meditation III investigates the existence of God, arguing that the idea of God is innate and that God, as a perfect being, cannot be a deceiver
• Meditation IV delves into the nature of errors and mistakes, suggesting that they stem from human free will rather than defects in God's creation
• Meditation V focuses on the existence of material things, with Descartes presenting proofs for the existence of God based on clear and distinct ideas
• Meditation VI concludes that physical objects exist due to a natural inclination to believe so and argues for the real distinction between mind and body, despite their intimate connection
• Descartes does not think he cannot doubt that he is "here, sitting by the fire, wearing a winter dressing-gown"
• Descartes shifts from considering the hypothesis of dreaming to the hypothesis of deception by a higher power to explore the most radical form of doubt
• Descartes does not explicitly address the doubt of mathematical truths like "2 + 3 = 5" in Meditation I
• The provisional conclusions of Meditation I do not explicitly include that a demon has deceived Descartes into believing he has hands or that Descartes doesn't know he has hands
• Skepticism


  Doubt or questioning of knowledge claims
• Modus Tollens


  Logical argument form where if the consequent is false, then the antecedent is also false
• Modus Ponens


  Logical argument form where if the antecedent is true, then the consequent is also true
• Contextualism


  Belief that the truth of knowledge claims depends on context
• Invariantism


  Belief that knowledge claims are context-invariant
• Modus Tollens: If P implies Q, and Q is false, then P is also false
• Modus Ponens: If P implies Q, and P is true, then Q is also true
• Skeptical Argument: If one cannot prove they are not a brain in a vat, they cannot know they have hands
• Moore's Proof of External World: Claiming the existence of hands as evidence for the external world
• Inconsistent Triad


  Three premises that cannot all be true simultaneously, necessitating the rejection of at least one
• Closure Principle


  If P entails Q, and one knows P, then they are in a position to know Q
• Moore likely thinks that one has proved a conclusion from some premises only if one knows the premises
• Moore probably doesn't think that one has proved a conclusion from some premises only if one is able to prove the premises
• Moore likely thinks the premises of his proofs are different from their conclusions because the premises are the starting points, while the conclusions are what he aims to establish or prove based on those premises
• Moore would likely consider "It is snowing, therefore it is snowing" as a valid argument, and agree that you have proved that it is snowing if you know the premise