excerpts from Ayer’s Language, Truth and Logic

Ayer introduces his ‘criterion of verifiability’ near the beginning of chapter 1 (pp. 33-45). What is the purpose of this criterion of verifiability? Ayer states his criterion in rough terms on p. 35. He spends the next three pages getting clearer on the criterion. What notion in particular is he trying to clarify, and what are the clarifications he offers? So far he has been talking about whether sentences are ‘factually significant’. You might think this is the same thing as being meaningful (vs. being nonsensical), but we learn on p. 41 that some sentences are meaningful even though they are not factually significant. What kind of sentences are those? Putting all of the pieces together, Ayer has given us a theory of what it is for a sentence to be meaningful. Try to state exactly what it takes, according to Ayer, for a statement to be meaningful.

On pages 114-115, Ayer then tries to show that statements about God do not have what it takes for a sentence to be meaningful. Thus, all claims about God are meaningless. How does Ayer show this on pages 114-115? What is the point of the bottom paragraph on p. 114? What is the point of the large paragraph on p. 115? Does Ayer therefore think that God does exist? Does he think that God doesn’t exist? Be careful!

We will go through this argument in class, so don’t worry if you don’t understand it all before hearing the lecture, but it will still be useful to figure out what you can prior to the lecture.

Some Terminology:

When he talks about what is ‘demonstratively certain’ or what can be ‘demonstratively proved’, he means what is absolutely certain or what can be proven absolutely.

By 'a priori' he means something that we can know to be true prior to empirical investigation. For example, you can just think about the sentence '5+7=12' and know this is true without doing any investigation of how things are in the world. Similarly, you can know that the sentence 'All bachelors are unmarried' is true without taking a poll of bachelors. You could say that we can know these to be true (and '7+5=3' to be false) prior to empirical investigation because these are true (or false) merely in virtue of the meanings of the words. These statements are a priori. In contrast, the sentence 'all rabbits are smaller than 20 feet tall' is something you could only know by having looked at how things (i.e., rabbits) are in the world. Like most sentences we use, this sentence is 'a posteriori'. If I told you there was a rabbit in Australia that is 40 feet tall, you would probably be incredulous and think it highly likely that I was exaggerating or lying. If I told you that there was a married bachelor in Australia, you would instead think that I was using my words incorrectly or that you were somehow misunderstanding me.