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