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Popper Is Fallible

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I just read a little of The Myth of the Framework by Karl Popper. I noticed two oversights I thought were worth pointing out. Both quotes are from page 175, and the first immediately precedes the second.

If we eliminate from language ambiguous terms like 'yesterday', a term which today means something different from what it will mean tomorrow, and if we take some further similar precautions, then it follows from Tarski's theory that every statement in this purified language will be either true or false, with no third possibility.

The issue Popper is worried about is evaluating whether the statement "Yesterday was Sunday." is true. He thinks this will be ambiguous, because it depends on what day we evaluate it. And his solution is to purify our language by removing all terms with variable meaning (presumably all pronouns too).

But this is very silly. All we have to do to decide if "Yesterday was Sunday." is true is to substitute in referenced concepts before saving the sentence for later evaluation when the references might not work any longer. What I mean is here 'yesterday' means 'the day before November 17, 2003'. The day before November 17, 2003 will always be Sunday whenever we evaluate the sentence. (And even if our calendar system should change, the meaning and truth of the sentence will not.) So, no purified language is necessary, if we will only bother to pay attention to the actual content of the sentence (alternatively, we could keep the form of the sentence exactly the same, but save with it all relevant data, such as in this case the date it was written).

Moreover, we can have an operation of negation in our language such that if a proposition is not true, then its negation is true.
This shows that of all propositions one half will be true and the other half false. So we can be sure that there will be lots of true propositions, even though we may have great trouble in finding out which they are.

I think this is actually quite funny. Yeah, there are lots of true propositions when you include the negation of false propositions... But most of them are things like, "I did not go to England yesterday," and "My house is not painted red," and "My name is not Fred." In reality, it makes sense to say there are a lot more ways to be wrong than to be right.


Elliot Temple on November 17, 2003

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