Ayer, “The Elimination of
Metaphysics”
Thesis: Traditional
disputes in philosophy are as unwarranted as they are unfruitful.
Main Argument:
P1: Metaphysical
claims do not have any factual content.
1a: A
claim has factual content only if there is in principle some sensory experience
is relevant to its truth value.
[Verification Principle]
1b: No possible sensory experience is
relevant to the truth value of metaphysical claims.
[Metaphysical claims are supposed to be
transcendental—i.e., about the world beyond experience.]
P2: Metaphysical
claims are not logically true/false.
[They are not trivially true or false in virtue of
their truth-functional logical form.]
(P3): A claim is cognitively significant only if it either has
factual content or is logically true/false.
[Logico-Empiricist Criterion of Cognitive
Significance]
C: Metaphysical
claims are not cognitively significant.
Verification Principle:
A.
A
claim has factual content only if there is some sensory experience that can establish
its truth.
[Counter: “There is life on Alpha Centauri.”]
B.
A
claim has factual content only if there is in principle some sensory experience
that can establish its truth.
[Counter: “All humans are mortal.”]
C.
A
claim has factual content only if there is in principle some sensory experience
that can establish its falsity.
[Counter: “Some human is immortal.”]
The
Argument Against First Principles:
Definition:
First Principles =df provide a certain basis
for our knowledge (they are the foundations for a deductive system of beliefs)
P1: First Principles cannot be a posteriori.
1a: They
cannot be empirical hypotheses/laws of nature.
[These are not certain since they are in principle refutable by some
empirical evidence.]
1b: They
cannot be introspective judgments.
[Either such judgments are not certain or there is no valid inference
from them to claims about the external world.]
P2: First Principles cannot be a priori.
2a: All
a priori truths are tautologies.
2b: From a tautology only other tautologies can be validly
inferred.
2c: So
if First Principles are a priori then they cannot validly support empirical
claims—thus the resulting system would be either incomplete or lack certainty.
(P3)
First Principles have to be either a posteriori or a priori.
[Logico-Empiricist Criterion
of Cognitive Significance]
C: There can
be no First Principles