sqeecoo wrote:
Well, yes, I am a full-blooded Popperian :P
But again, I don't deny the messiness of science at all. I am just saying that falsification can be described validly in logical terms however messy it might be in practice, whereas verification cannot. What is impossible is conclusive falsification, which you seem to be expecting to get. Like verification, that's just something we can't get, unfortunately

Inconclusive falsification, on the other hand, is perfectly possible, and is what scientific reasoning consists of. As long as you adopt Popper's methodological rule not to accept any auxiliary hypotheses that don't increase the testability of the theory in question, they are not a problem. And interpreting test results is of course hard. Again, you don't get conclusive or "probable" falsification, you get tentative falsification. But you have a rational, logically watertight method that you can use to inconclusively but perhaps successfully search for errors.

sqeecoo wrote:
I don't think any falsificationist (certainly not Popper) ever said conclusive falsification is possible, so only "inconclusive falsificationism" exists

Conclusive falsification would be falsification where you prove (or have "sufficient evidence", whatever that is supposed to mean) that the theory in question is false. Inconclusive falsification is falsification where the test is as much a conjecture (i.e. guess) as the theory in question.

The latter can't be used to attain any level of rational certainty, obviously, but it can be used to avoid actual errors even if you don't "know" (in the sense of justified true belief) that you have avoided them. Unfortunately, that's the best we can do. But look how much we have achieved despite that!

sqeecoo wrote:
The logic is crisp - if the falsifying test is true, the theory is false. That's where the logic ends. Figuring out whether the test is correct is where it gets muddy.

The problem with abductive "reasoning" is twofold. First, it is not reasonable - the logic of falsification is abstract and simple, but there is NO logic to abduction. There is simply no logical connection between the theory "fitting the evidence" and the theory being true.

Second, there is always an infinite number of theories that fit the evidence. The evidence does not tell us which one to choose - it doesn't really do anything at all, actually. With falsification, accepting the evidence means we must reject the theory.

Of course, abduction is correct in saying that we should fit the theory to the evidence in the sense that if the theory DOES NOT fit the evidence, either the evidence or the theory must be rejected. This is what falsificationism is all about.
However, abduction usually claims that if the theory fits the evidence, that gives us some "degree of probability/confidence" that our theory is true. Falsificationism disagrees, and is sincere about all our theories being purely conjectural. If you accept that, and agree that the point of checking whether the evidence and the theory fit is in seeing whether there are any places where it DOES NOT fit, that our positions are identical.

sqeecoo wrote:


The logically necessary connection is that if the evidence (or rather, the statements about the world, about the "evidence") that contradict the theory are true, the theory is false. In other words, if a logical consequence of the theory is not true, the theory is false. Formally:

A->B
~B
____
~A

This is modus tollens.

For instance, we have the theory "All swans are white". Let's see how falsificationism and abduction handle it:

ABDUCTION:

CASE1: Check all swans we see. All these swans are white. The theory fits the evidence, and is "probably true", "proven", "reasonable to believe" or whatnot.

CASE2. Check all swans we see. Not all these swans are white. The theory does not fit the evidence, and is disproven.


FALSIFICATIONISM:

CASE1: Check whether the theory is falsifiable (i.e. whether it contradicts any conceivable physical events). If yes, accept it as a scientific theory. Actively look for a non-white swan. We find none. The theory is tentatively retained until further notice - but it is as conjectural and unproven as before the testing.

CASE2: Check whether the theory is falsifiable (i.e. whether it contradicts any conceivable physical events). If yes, accept it as a scientific theory. Actively look for a non-white swan. We find one. The theory is tentatively considered falsified until further notice - but this is as conjectural and unproven as in CASE1. Additionally, someone might not accept the truth of the test, and test the test - for instance check whether the swan in question has been painted non-white.

sqeecoo wrote:
All scientific theories are logically universal however, since that's the only way they can have any explanatory power and contain interesting information.