Berkeley’s Argument for Idealism—
1. We directly perceive only our own ideas. (ideaism)
2. All our ideas come through sense-experience. (concept empiricism)
3. There are no ideas in our sense-experience corresponding to the term
“material substance” (and similar terms).
4. If there are no ideas in our sense-experience corresponding to the term
“material substance” (and similar terms), then the term “material
substance” (and similar terms) are meaningless.
5. If there are no ideas in our sense-experience corresponding to the term
“material substance” (and similar terms), then the terms for ordinary
objects (like “table” and “tree”) are meaningful only if the ideas
corresponding to them are of their perceptible qualities.
6. The terms for ordinary objects are meaningful.
7. Therefore, the term “material substance” are meaningless and
ordinary objects consist of nothing more than their perceptible
qualities. (To be is to be perceived.)
Logical Positivism
 philosophical movement that began around 1900 and has been
influential up to present day
 Much of philosophy, particularly metaphysics, consists of confusions
of language and is cognitively meaningless.
 Science is the only legitimate way to understand the world.
 The job of philosophers is to clear up the confusions of language that
exist in ordinary discourse and in doing so to enable science to
proceed from a sound logical foundation.
Verifiability Principle: A statement is cognitively meaningful (i.e., capable
of being true or false) if and only if it is analytic (i.e., its truth or falsity
depends entirely on its meaning) or empirically verifiable.
Verification Principle: The meaning of an empirically verifiable statement
is its method of verification.
“protocol statement”—a first-person singular, present tense, introspection
report of one’s immediate sensory experience (e.g., “I seem to be seeing a
green object” or “I am being appeared to greenly.”)
“empirical hypothesis”—statements that relate protocol statements to each
other (e.g., If a bright streak of light in the sky appears suddenly to me,
then I shall soon experience a loud booming sound.)
One positivist proposal
All meaningful empirical statements are either protocol statements or
empirical hypotheses or can be logically analyzed as one or the other.
Problem: How do we get from protocol statements and empirical
hypotheses to statements about “unobservable” theoretical entities?
Possible Solutions—
1. Accept the view that statements about theoretical objects are
cognitively meaningless.
 semantic instrumentalism – Theoretical terms are merely logical
constructs that are useful in relating protocol statements to each
other.
2. Define theoretical terms in non-theoretical (observational) terms.
 reductive empiricism – Scientific theories should not be interpreted
as referring to “unobservable” objects but rather as statements
about “observable” objects.
 Problem – How do we interpret theories, which appear to refer to
neutrinos, black holes, etc., as statements about “observable”
objects, and ultimately as protocol statements?
3. Abandon the correspondence theory of truth and replace it with a
coherence or a pragmatic theory.