What is knowledge?
• what is the diff between knowledge and belief?
◦ What is the point in saying, i don’t believe, i know!
• Why is knowledge important
◦ sense of security, planning and ' building'
◦ position claiming we have no knowledge
◦ does the skeptic claim that we can know that skeptictism is true
• know how, know who, and know what
◦ three different ways we use the word 'know'
◦ is there a common factor?
Necessary and Sufficient Conditions
• necessary conditions
◦ when (if x then y) us true then I is necessary condition for x
▪ ex. oxygen is a necessary condition for a match lighting, living in Canada is a
necessary condition for living in Canada
• Sufficient conditions
◦ when (if x then y) is true
Knowledge, belief, truth
• knowledge implies belief
• the belief- desire explanation system (folk psych) mental states: beliefs and desires
• ex. John went to the fridge and got a beer
◦ Desire: john wanted a beer
◦ Belief: john believed beer was in the fridge
• altering either belief or desire alters the action
• desire is a mental state which represents the world as we wish it to become (goal)
• belief is the stare which represents the worlds current 'configuration'
• rationality is the ability to use beliefs to generate actions which transform the world to
• knowledge implies belief
◦ that is, if S knows P then S believs that P
◦ can we show this
▪ suppose that S knows that snow is white
▪ now suppose that S does NOT believe that snow is white
▪ what happens is we ask him whether snow is white?
▪ Is he says 'yes' then he must believe that snow is white (so long as he in
▪ is he says 'no' then he can't know that snow is white
▪ is he says 'i don’t know' then he cant know what snow is after all
• is this a good argument
◦ exam situation: a 'guess' based on knowledge you don’t know you possess?
• Knowledge implies truth
◦ that is, if S knows that P then P is true
◦ can we show this? ▪ Suppose S knows that snow is white
▪ now, suppose that snow is NOT actually white
▪ But, if somebody knows something you can rely on that. If someone knows that
the bus leaves at 4:15 then you can rely on that
▪ you can reply on something if you know its true. You cant rely on the bus leaving
at 4:15 if it really leaves at 4:10
▪ is snow is actually NOT white, then we cant rely on its being white
▪ so if snow is actually NOT white, then S does not know that snow is white
• Belief and truth are necessary conditions of knowledge
• but they are not sufficient
• to show that, we need a case where somebody believes something which is true, but
they don't know it
◦ ex. Groundhog day
• generally speaking, sometimes when one comes to believe something by accident
which just happens to be true we will have a case of true belief which is not knowledge
Knowledge and Justification
• is something more needed besides truth and believing to turn a belief into knolwdge?
• Lets call this extra thing justification
• what is justification
◦ havinga good reason for a belief
◦ what kind of reasons
▪ prudential? No (even if you accepted Pascal's Wager, you would end up
believing in Gods existance but not knowing that He existed)
▪ therfor evidential reasons
• based on arguement? Not necissarily (we know some things 'directly'; ex.
• Sober's moral analogy
◦ we sometimes talk about whether actions where morally justified or not
▪ in one sense of this idea, on is morally justified if ones actions do not violaet an
of your duties of if one has a right to do the action
• perhaps there a similar sense of 'epistemic justification'
◦ one is epistimically justified is one 'has the right' to belive or if one has fulfilled the
duites one 'owes' to one's beliefs (or their formation)
◦ but what are these duties?
◦ Can one make a mistake and still be justified?
• We might use the idea of 'virtue' here
◦ the morally virtuous person is one who does the right thing in the realm of action
• The JTB theory of knowledge
◦ S knows that P is and only if
▪ P is true
▪ S believes that P
▪ S is justified in believing that P
• The JTB theory explpains a great mnat knowledge claims
◦ i know that I live in toronto ◦ why? Its true, i believe it and there is justification
• The JTB theory also explains
• But the JTB theory seems to fail in some cases
◦ the principles of failure
▪ one can be justified in believing