EPISTEMOLOGY AND SKEPTICISM

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EPISTEMOLOGY AND SKEPTICISM

• Epistemology df. Theory of knowledge
  investigates the origin, nature, limits, and
  validity of human knowledge. (From the Greek word
  epistm meaning knowledge.)
• Skepticism df. Doubt or denial that knowledge is
  possible. If there is a truth about things we
  cannot know what it is. Gould The view that
  either doubts all assumptions until proved, or
  claims that no knowledge is possible. (From the
  Greek word skepsis meaning inquiry or
  questioning.)

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WHAT CAN WE KNOW?

• Nagel The inside of your mind is the only thing
  you can be sure of.
• There is no outside of the mind, inside is meant
  to contrast with the external world.
• The external world df. everything outside the
  mind or, relative to an individual, the world
  outside of my mind or the world other than my
  present experience or the world other than the
  present contents of my mind.

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THE PRIVACY OF EXPERIENCE

• All beliefs about the external world are based
  upon sense experience we know the outer world
  through one or a combination of the five senses.
• And everyones sense experience is private - part
  of the present contents of his or her mind.
• Two or more people can see the same external
  world object like a tree, but one person cannot
  have another persons seeing, or touching of such
  an object. Also, only you can have your hearing,
  tasting, or smelling.

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ACTS AND OBJECTS OF EXPERIENCE I

• Acts or events of experience and objects of
  experience are typically distinct.
• For instance, your seeing this slide and the
  slide itself are two different things, as are
  your seeing and your neighbors seeing. If you
  close your eyes your seeing ends, but not that of
  the person next to you, and the object of sight
  does not cease to exist.
• Sometimes events of experience and the thing
  experienced are the same. For instance, there is
  no distinction between feeling a pain and the
  pain felt - when the feeling ends so does the
  pain felt, and vice versa.

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ACTS AND OBJECTS OF EXPERIENCE II

• How do I know that my seeing of a tree is not
  like the feeling of a pain - that is, that there
  is no tree apart from my seeing it? Could my
  seeing a tree be a hallucination?
• A challenge of skepticism is that my supposed
  perceptions of a mind-independent external world
  might all be false, might be like dreams or
  hallucinations.

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THE EXTERNAL WORLD I

• If my experience is part of my mind, then how do
  I know that the external world exists beyond my
  experience?
• Could it be the case that my experience is all
  there is and there is nothing beyond or behind
  it?
• If you say that if the external world did not
  exist you would not see what you see, then the
  question is how do you know that?

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THE EXTERNAL WORLD II

• Consider these two possibilities
• 1. I see the external world because it is there.
  (It is mind-independent.)
• 2. The external world is there because I see
  it. (It is mind-dependent.)
• How can I decide philosophically between 1 and 2?

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BEGGING THE QUESTION

• Can I trust the evidence of my senses? Or is
  what they seem to tell me false?
• I cant simply appeal to my senses to prove that
  the external world exists, because this is the
  very thing which has been called into question.
• This would be to reason in a circle (come back to
  where I started) or beg the question (assume to
  be true what I am trying to prove).

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SOLIPSISM

• Solipsismdf. I cannot know or prove anything to
  exist except myself.
• This seems logically impeccable but unbelievable.
  
• It is logically impeccable since, strictly
  speaking, I cannot know for sure or prove that
  anything exists other than the present contents
  of my mind.
• It is unbelievable because my animal faith in the
  existence of things other than my own mind is
  instinctual and emotional, and is stronger
  psychologically and is more practical than logic.

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MEMORY AND THE PAST I

• Our knowledge of the past is based on memory -
  without memory we would not know that we had
  existed before now.
• Memory is not always trustworthy. Sometimes
  things happened in the past that we do not
  remember, and it may be the case that we think
  that something happened which really did not. In
  such a case, what we seem to recollect did not
  really occur.
• Could it be the case that all of our memories
  of the past are mistaken?

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MEMORY AND THE PAST II

• It is logically possible that the universe came
  into existence just now, with its present size
  and complexity, and showing signs of a past - a
  false past to which human memories incorrectly
  point.
• You cant tell from the nature of memories
  themselves that they truly or falsely point to
  the past to which they apparently point.
• And you cant tell from analyzing your current
  experience itself that it has a cause. It is
  possible that it has no cause or that the cause
  is your thinking it.

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MEMORY AND THE PAST III

• A past cause of a present memory cannot itself be
  observed because it is past. The memory itself
  is present, but we cant tell from the memory
  itself whether or not it was truly caused by a
  past event.
• You cant prove that a principle like causality
  operates outside your mind by simply observing
  your mind, but you have no direct epistemological
  access to anything else.

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MEMORY AND THE PAST IV

• Because the reliability of memory as correctly
  pointing to a past which really occurred is what
  has been called into question, I cant rely on my
  memory to prove that the past is real. This is
  because, if I rely on memory to justify what has
  been questioned about memory, I am reasoning in a
  circle.

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SOLIPSISM OF THE PRESENT

• Solipsism of the presentdf. I can only be sure
  of the contents of my own mind now.
• Because all of my memories might be false, and I
  might have begun to exist just now, I can only
  know for certain that I exist at the present
  moment.
• Solipsism shuts me up in the world of my own
  mind, and I cant be sure that anything other
  than my mind and mental history is real.
• Solipsism of the present confines my existence to
  the contents of my mind at the moment, and I
  cant be sure that anything exists other than
  that.

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TWO VERSIONS OF SKEPTICISM ABOUT THE EXTERNAL
WORLD

• The weak version of skepticism about the external
  worlddf. Perhaps the external world exists, but
  how can I know that it resembles my perceptions?
  There is no way for me to get beyond my
  perceptions to compare them with the world
  itself, so I cannot know whether the world is
  like my perceptions of it or not.
• The strong version of skepticism about the
  external worlddf. There is no way for me to know
  that there is a world beyond the present contents
  of my own mind.

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SCIENCE AND THE EXTERNAL WORLD

• Science does not prove, but simply accepts that
  the external world exists.
• Science is just as vulnerable to skepticism as
  common sense. This is because, like philosophy,
  it begins with the data of common sense. And
  common sense is what has been questioned.
• But it is just the data of common sense which
  skepticism questions. Accordingly, science
  cannot prove that there is a mind-independent
  reality to which our sense experience is
  certainly related.

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VERIFICATIONISM I

• verificationismdf. Reality is what we can
  observe. Nagel Our idea of the things that
  exist is just our idea of things which we can
  observe.
• For instance, your idea of a gorilla in the next
  room is your idea of what you would observe if
  you went into the room and looked.
• The verification theory of meaningdf. The
  meaning of a word or sentence is what it would
  mean to verify it through sense observation. The
  meaning of apple is what you would perceive in
  perceiving that kind of object.

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VERIFICATIONISM II

• What cannot be verified through perception, at
  least in theory, is meaningless.
• That there is a gorilla in the room across the
  hall is true or false based on what I observe
  when I go look.
• That there is an invisible rhinoceros in the room
  is neither true nor false, but meaningless since
  nothing would count as verifying or falsifying
  it.

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VERIFICATIONISM AND SKEPTICISM I

• Skepticism says that maybe what appears to be
  reality is my dream - that there is no reality
  beyond the appearance.
• Verficationism says that one can only talk
  meaningfully about a dream as something from
  which you can wake up. Hence to talk about life
  as a dream is meaningless.
• It is meaningless to say that everything is a
  dream if there is not something which is not a
  dream. A dream which never ends is not really a
  dream since there is nothing from which to wake
  up.

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VERIFICATIONISM AND SKEPTICISM II

• The skeptic says that maybe I am hallucinating
  the external world, or that it is an illusion.
• The verificationist says that talk of
  hallucinations or illusions is only meaningful
  against a background of a non-hallucinatory,
  non-illusionistic reality with which
  hallucinations and illusions can be contrasted.
• We can only talk meaningfully about something
  like a hallucination or illusion if there is a
  reality with which the appearance can be
  contrasted to show that it is only an appearance.
  Therefore it is meaningless to talk of external
  reality as a hallucination or illusion.
• To say then that everything is appearance is
  meaningless.

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VERIFICATIONISM AND SKEPTICISM III

• Verificationism says that the possibility that
  there is no external world or that everything is
  not as it seems is meaningless. Thus the skeptic
  is wrong to see this as a meaningful possibility.
• But Nagel says the verificationist argument is no
  good unless reality can be defined as what we
  observe.
• The problem with this is that it makes reality
  dependent on minds or observers, and there seems
  to be no logical reason why a world could not
  exist that no one or no mind observed.

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PROBLEMS WITH VERIFICATIONISM

• 1. We first have to understand the meaning of a
  statement before we know what it would mean to
  verify it.
• 2. Some statements are meaningful which cannot
  be verified even in theory.
• 3. Science uses unobservable entities like
  electrons in its theories, and verificationism
  would make such entities used meaningless since
  unverifiable.
• 4. Verificationism cannot be used to verify
  itself, and so on its own principles cant be
  known to be true.

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SKEPTICISM AGAIN

• For the skeptic, if external objects are
  observable it is because they exist. We dont
  define existence in terms of observability.
• Since the external world can be separated
  conceptually from observations, it is a
  meaningful possibility that such a separate
  reality does not exist, but only my perceptions.

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THE EGOCENTRIC PREDICAMENT

• The egocentric predicamentdf. The problem of
  arguing to anything which exists beyond the
  present contents of my own mind. I am logically
  trapped within the circumference of our own
  momentary experience in that I cant be sure that
  there is anything more than the experiences
  themselves.

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SKEPTICISM AND ANIMAL FAITH

• Skepticism may be logically impeccable, but it is
  psychologically unbelievable.
• We have an unquestioned, instinctive, or what
  Santayana called animal faith in the external
  world.
• We respond with animal faith to the external
  world because we cannot do otherwise, and because
  it is in our practical interest to do so.
• It would also be a waste of time for science to
  question the existence of the external world
  whose existence it assumes.