PHIL1003 Lecture Notes - Lecture 13: Dream Argument, Cogito Ergo Sum, Analytic Geometry
The Problem of Knowledge
• Epistemology: The theory of Knowledge
• What is knowledge?
o Knowledge is true justified belief
o S knows that P means
▪ S believes that P
▪ P is true
▪ S is justified in believing that P
• Must knowledge be certain?
o I may give reason for holding a belief or a conclusive proof: these
are very different things
o Greek skeptics (530BC) claim that the process of justifying beliefs
leads to an infinite regress – so we can never know anything!
▪ The Dogmatists respond – we can have certain knowledge
• The problem of a skeptical challenge will only arise if
other beliefs are cited in justification of the one that
is challenged
• We can know things for certain through
o Immediate knowledge of basic propositions
or axioms that are self-evident and require no
further justifications
o Mediate or derived knowledge based on this
▪ Two typed of dogmatists: Empiricists and Rationalists
• What is the source of immediate knowledge?
• What underwrites its certainty?
• Two main competing answers: sense-experience and
reason
o Those who opt for sense-experience are
called empiricists and those who opt for
reason are called rationalists
• What (if anything) can we really know?
o Existence of the external world?
o Other minds?
o Mathematical and geometric truths?
o God or other supernatural entities?
o The extent to which the external world resembles the way it
appears to be?
• How can we come to know it?
• René Descartes
• 1596-1650
• Made notable contributions to mathematics and science
• Invented analytic geometry
• Philosophy was integrated with his projects in mathematics and
science
• His mission
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