On Aug 22, 10:34 am, Davej hotmail.com> wrote:

Same applies to your theory about "one holding empirical beliefs" ad
ignoratio

David Hume qualified his own Scepticism by pointing out that to live
at all we have perpetually to make choices, decisions, and this forces
us to form judgements about the way things are, whether we like it or
not. Since certainty is not available to us we have to make the best
assessments we can of the realities we face - and this is incompatible
with regarding all alternatives with equal scepticism. Our Scepticism
therefore needs to be, as he put it, mitigated. It is indeed doubtful
whether anyone could live on the basis of complete Scepticism - or, if
they could, whether such a life would be worth living. But this
refutation of Scepticism, if refutation it is, is not a logical
argument.

In practical life we must steer a middle course between demanding a
degree of certainty that we can never have and treating all
possibilities as if they were of equal weight when they are not.

Story of Philosophy
by Bryan Magee
http://www.amazon.com/Story-Philosophy-Bryan-Magee/dp/078947994X

According to perspectivalism and relativism, a proposition is only
true relative to a particular perspective. Roughly, a proposition is
true relative to a perspective if and only if it is accepted,
endorsed, or legitimated by that perspective.

"a propensity, which inclines us to be positive and certain in
particular points, according to the light in which we survey them at
any particular instant". (Treatise 1.4.7, 273)

http://en.wikipedia.org/wiki/David_Hume

Here is a sketch of how Hume's "system" works:

When I wake up and hear certain familiar sounds, I come to believe
that it is raining. My judgment is a representation because there are
perceptions of the sight and feel of rain, perceptions that I will
have if I go to the window and look, or if I go outside and feel the
rain. These perceptions are the "facts" my judgment is about. My
judgment is the result of a causal process: given my past associations
between a certain kind of soud and the presence of rain, plus a
present impression of that certain kind of sound, I expect that if I
go to the window I will see it raining on my roses. My expectation is
representative, and capable of truth or falsity. So if I go to the
window to look at my roses, and see that Charlotte is hosing off the
screen on our bedroom window, then my belief misrepresented the facts,
and what I believed was false. But the facts that lead me to regard my
judgment as true or false, as accurately representing or as
misrepresenting those facts, are themelves perceptions — impressions,
and they are not representative of anything beyond themselves.

...Hume has shown that a system allegedly built on more secure
"foundations" — "principles" that go beyond perceptions and are
somehow supposed to validate them — is a metaphysical pipe-dream, not
the legitimate basis of a coherent account of human nature, judgment,
and belief.

But in rejecting the "ultimate principles" of traditonal metaphysics
as incoherent, isn't Hume committing himself to an equally
questionable picture of the ultimate nature of reality, one that says
that there are only impressions, ideas, and the inferences we make
from them? No. In choosing to restrict his discussion of questions
about the nature of human nature in terms of perceptions, Hume is
answering what he takes to be empirical questions in the only coherent
way that they can be answered. Metaphysics tempts us to regard these
answers as making claims about the ultimate nature of reality. Hume
shows us how to resist that temptation. It is in this that the depth
and originality of his project for the reform of philosophy consists.

http://plato.stanford.edu/entries/hume/