Philosophy 024: Big Ideas

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Philosophy 024 Big Ideas Prof. Robert DiSalle
(rdisalle_at_uwo.ca) Talbot College 408,
519-661-2111 x85763 Office Hours Monday and
Wednesday 12-2 PM Course Website
http//instruct.uwo.ca/philosophy/024/
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Certainty and Skepticism some basic
questions (skepticism from the Greek ?????????,
to examine, inquire) Can any human belief or
perception be placed beyond doubt? Once the
possibility of doubt has been admitted, can it
ever be removed? Can any beliefs still be
justified as knowledge? Are there any beliefs
that are worthy of being accepted as foundations
for other beliefs or inferences? Can a genuine
distinction be made between appearance and
reality? Can skepticism itself be a consistent
point of view?
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Some basic skeptical and non-skeptical
attitudes Dogmatic skepticism Nothing can be
known. Nothing is true. All human claims to
knowledge are false. Pyrrhonian skepticism
Certainty is impossible, so the wise person
should suspend judgment about theoretical
matters. Empiricist foundationalism The senses
provide the ultimate criteria for justifying
belief. Rationalist foundationalism The senses
give subjective or even deceptive appearances,
and only reason provides a foundation for certain
knowledge. Authoritarianism Certain persons
(e.g. priestly authorities, authors of sacred
books) are empowered to know and to speak the
truth on fundamental matters.
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Some underlying principles of skepticism Relativit
y of perception Perceptions vary according to
circumstances of -- time and place, --physical
conditions, the nature of the object, and the
nature of the individual perceiver. Conclusion
Contrary to the empiricist, our own immediate
sensations are no guide to objective
circumstances.
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The problem of infinite regress Any rational
argument must depend on premises. And these
premises must be deduced from other premises. And
those most be deduced from still other premises.
And so on and on Or, the problem of
conventionalism In order to avoid an infinite
regress, we can simply choose a principle as an
axiom, and so refuse to justify it. But since the
axiom cannot be deductively justified, it is
arbitrary. Conclusion Contrary to the
rationalist, reason cannot provide a foundation
for true belief.
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The problem of human variability and frailty For
every opinion held by any reputable human being,
there is a contrary opinion that has been held by
equally reputable human beings. Every opinion
that now seems foolish has been, at some other
time or place, regarded as absolute truth by
reputable authorities. Generally, what human
beings regard as certain varies according to
history and culture. Conclusion Contrary to the
authoritarian, no human beings can be regarded as
having some special insight into the truth.
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Montaigne Skepticism to mitigate
doubt Credulity Excessive trust in reports of
others Incredulity Excessive confidence in the
wisdom of ones own judgment. Skepticism a
sense of the fallibility of human judgment We
must bring more reverence and a greater
recognition of our ignorance and weakness to our
judgment of natures infinite power.For to
condemn improbable things as impossible is
rashly and presumptuously to pretend to a
knowledge of the bounds of possibility.
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Descartes Discourse on the Method of Rightly
Conducting Ones Reason and Searching for Truth
in the Sciences I do not intend to teach the
method, but only to speak about it. For as you
can see from what I say of it, it consists more
in Practice than in Theory, and I called the
treatisesEssays in this Method, because I hold
that the things that they contain could not have
been discovered without the method, and that
through them you know its value.
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Discourse on the Method An analytic method of
distinguishing truth from falsehood, and of
building scientific knowledge on secure
foundations Optics A mathematical theory of the
reflection and refraction of light, including the
discovery of the Law of Refraction Geometry The
invention of modern analytical geometry,
including the reduction of geometrical curves and
figures to algebraic relations Meteorology A
study of atmospheric phenomena, including a
derivation of the colours of the rainbow from
principles of optics. (Descartes, 1637)
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Rules of the Cartesian method Accept nothing
as true except what is apprehended so clearly and
distinctly as to be beyond any doubt. Divide each
difficulty into as many separate parts as is
possible and necessary to resolve them. Begin
with the objects that are the simplest and the
easiest to know, and gradually ascend to the most
complex and difficult--even assume such an order
if none exists naturally. Make such a complete
review and enumeration, at the end, as to be sure
that nothing important has been
omitted. Leibnizs gloss Take what you need and
do what you must, and you will get what you want.
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The Cartesian skeptical method (radical
doubt) Turning doubt against itself What would
happen if I systematically attempted to doubt
absolutely everything? Could such an attempt
really succeed? Or would I discover that there
are certain principles that it is absolutely
impossible to doubt? If I begin by treating all
my ideas as false, will I discover that my mind
contains ideas that bear unmistakable marks of
truth? (Descartes, Meditations, 1641)
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Cogito ergo sum I think, therefore I
am. While I wished to think that everything was
false, it was necessarily the case that I, who
was thinking this, was something. this truth,
I think, therefore I am, was so firm that all the
most extravagant assumptions of the sceptics were
unable to shake it from the very fact that I
was thinking of doubting the truth of other
things, it followed very evidently and very
certainly that I existed.
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Now that we know one certain truth, we ask, in
what does its certainty consist? What rule can be
developed for recognizing certain truths? Nothing
convinces Descartes of the truth of Cogito, ergo
sum, except the fact that he clearly and
distinctly perceives it to be true. Therefore I
could adopt as a general rule that those things
that we conceive very clearly and distinctly are
true. The only outstanding difficulty is in
recognizing which ones we conceive distinctly.
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Can ideas have marks that tell us whether they
correspond to something real? Descartes From my
doubts I know that I am limited and
imperfect. But the idea of God has such
perfection in it that I know that its cause must
be something outside of me, i.e., a perfect
being. Nothing in any other idea implies the
existence of the corresponding thing. I can be
certain of the properties of a triangle, but
nothing I can know about the essence of a
triangle can tell me whether there is such a
thing as a triangle. But the idea of God contains
existence in its essence. That God exists is as
certain as that a triangle has three sides.
(Ontological Argument)