Ayer and Popper Quotes & ...

Ayer-The Elimination of Metaphysics

 “Must he not begin, as other men do, with the evidence of his senses” (6).  

Empiricism: the claim that all knowledge, indeed all thought, originates in sense experience.  That is, in order for some thought or some sentence to have content, to make sense at all, it must be traceable to some sensory experience.  

“Surely from empirical premises nothing whatsoever concerning the properties, or even the existence, of anything super-empirical can legitimately be inferred” (6)

Here is where we get the infamous verifiability criterion for meaningfulness.  Here is Ayer’s statement of it:

“a sentence is factually significant to any given person, if, and only if, he knows how to verify the proposition which it purports to express—that is, if he knows what observations would lead him, under certain conditions, to accept the proposition as being true, or reject as being false” (7).

Here is a more precise statement of the verifiability criterion for meaning:

VCM:A statement is meaningful iff it is either in principle possible to empirically verify it or it is analytic: 

A statement is analyticjust in case it is true in virtue of meaning alone—that is, the predicate is contained in the subject.

Problems: What are some of the problems we went over in class? Can you think of any others?

                        

Popper-Falsificationism

Note that Popper clearly rejects Ayer’s and the logical positivists attempt to separate science from non-science.  

“I thus felt that if a theory is found to be non-scientific, or ‘metaphysical’ … it is not thereby found to be unimportant, or insignificant, or ‘meaningless’, or ‘nonsensical’.  But it cannot claim to be backed by empirical evidence in the scientific sense—although it may easily be, in some generic sense, the ‘result of observation’” (12).

Towards a better way to demarcate:

“It was precisely this fact—that they [Marxism & Psycho-Analysis] always fitted, that they were always confirmed—which in the eyes of their admirers constituted the strongest argument in favor of these theories.  It began to dawn on me that this apparent strength was in fact their weakness (10).

But Einstein’s Relativity Theory is different:

“If observation shows that the predicted effect is definitely absent, then the theory is refuted.  The theory is incompatible with certain possible results of observation…” (11).

So, Popper believes that he landed on the correct way to demarcate the sciences from the non-sciences, where the non-sciences include the pseudo-sciences, metaphysics, religion, etc.  The criterion that distinguishes the sciences from all these others is falsifiability. 

Falsifiability: Some theory T is falsifiable just in case it is possible that some empirical data or result is incompatible with the predictions of T.

Important Implication: no scientific theory can be proven; they can only be falsified or attempted to be falsified

Problems: I will discuss some problems with Falsificationism in class. Can you think of any?