jean-claude,

 > The fact that scientific perceptions became shared by many doesn't make
> it more real.

I disagree. Verifiability is the test we use to distinguish
hallucinations from reality.

You can deny reality if you choose, but if you choose to accept that the
word "reality" has any meaning then you must accept *at the very least* the
idea that mutually shared hallucinations are more real than private
hallucinations.

David and Todd,

 >         Empiricism means to experience.

It means more than that. Here is Webster:

2 a : the practice of relying on observation and experiment especially in
the natural sciences b : a tenet arrived at empirically
3 : a theory that all knowledge originates in experience


Empiricism is the theory that all knowledge originates in experience and
which when put into practice calls for the reliance on observation and
experiment in the acquisition of knowledge.

If you believe something that cannot be verified by observation and
experiment then according to the tenets of empiricism that belief
does not constitute true *knowledge*. Belief in the existence of God is the
classic example. Such beliefs cannot constitute true knowledge to one who
accepts the tenets of empiricism, at least until someone finds a scientific
proof for the existence of God.

Logical positivism is really the subject most relevant here. Logical
positivism is the philosophical theory that statements which cannot be
verified empirically are meaningless.

I've argued against logical positivism in the past (I've been debating
philosophy and religion and science online for no less than 10 years
now.. my interests only recently changed to health and nutrition) and
one strong argument against logical positivism is similar to that to
which Todd Moody alluded: the statement "Statements which cannot
be verified empiricially are meaningless" cannot itself be verified
empirically. This would seem to undermine logical positivism
in that logical positivism appears to fail its own test. However upon
closer inspection one sees that this objection is itself an ineffective
argument unless we first accept the truth of logical positivism! It makes
no difference to the veracity of logical positivism that its central
statement cannot be verified, unless we first assume that statements
must be verifiable to be true. Therefore the central principle of logical
positivism is like the paradoxical "true but unverifiable statement" which
must exist in every formal system of logic according to Godel's theorem
(but that theorem is another juicy nugget upon which we could waste a
few thousand messages, so let's not).

I once used arguments from the philosophies of metaphysical idealism
and rationalism to attack empiricism and materialism and logical positivism
in order to defend my faith in a supreme being. However I have over time
come to believe  that we need empiricism/logical positivism to separate the
wheat from the chaff, in the field of health care and diet and nutrition and
health supplements (especially!) as well as philosophy. I suppose I'm just
tired of all the unsubstantiated unscientific balderdash that I see being
promulgated as "true knowledge" on the internet.

-gts