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Some people argue that we can not verify hypothesis but we can falsify them? I believe we can usually negate statements. So, if we can falsify statements, why cant we verify statements by falsifying their negation?

I do not ask if it is practicable to do so, but rather about the general possibility. Why does the distinction between falsification and verification of hypothesis makes sense, if we can negate statements. Of course, I am assuming the law of the law of excluded middle and the law of non-contradiction. But my thinking is motivated from the philosophy of sciences, and I do believe that in most sciences we can assume those laws to apply.

Why does it make sense to say that statements can generally not be verified, if we could verify them by falsifying their negation?

I am also thankful for any pointers to literature that might help me to answer these questions.

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    how is 'verifying them by falsifying their negation' different from rejecting a null hypothesis? – Dr Sister Oct 18 '12 at 0:12
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    Its not different. Thats exactly my point formulated a bit differently. I could have written, If we can falsify a hypothesis, cant we verify it by rejecting the corresponding null hypothesis? And if yes, why does it make sense to state claims such as: "We can not verify, only falsify.", as often heard in reference to Popper. The correct answer is that this is a wrong, too generalized interpretation of Poppers point. Of course, we can verify hypothesis. See the answer marked as correct. – FabianB Oct 18 '12 at 10:26
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The reason some empiricists (most notably Popper) have denied that we can verify an empirical hypothesis is that they were thinking of universally quantified statements such as

All ravens are black

This statement, the argument would go, cannot be verified: regardless of how many ravens one observes, there is always the possibility that the next raven will be white. Now, it can be falsified: finding one white raven is enough for this.

The problem with your suggestion, namely falsifying

It is not the case that all ravens are black

or, equivalently,

There is at least one raven that is not black

is that such a statement is as hard to falsify as the original statement is to verify -- and, conversely, as easy (!) to verify as the original statement is to falsify. This point is not new, of course; it was already made by Hempel back in the day.

  • Ok, there we go. As I was tought about Popper he claims that we can not verify anything. Maybe it would be more correct to say, that we cannot verify positively formulated universally quantified statements? So I guess I should go back and study the original works. Please note I have no background in philosophy but I am rather a scientist sneaking into these topics a bit. My problem was that I did not see a fundamental difference in verification and falsification of statements, because both represent just a different side of a medal. (switching roles by negation) – FabianB Oct 17 '12 at 21:46
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    Yes, the explanation for this focus on such universally quantified statements is that Popper (and the logical positivists before him) took that to be the form of most claims advanced in science -- the idea being that science is not interested in particulars. It is ironic that Popper is still something of a philosophical hero for many scientists, when in fact he held such radically sceptic views about confirmation, that no practising scientist could adhere to in practice. – Schiphol Oct 18 '12 at 11:29

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