Originally Posted by Allan
You have asked not one but 3 questions.
The first is whether micro drag exist or is BS. To that I answer an unequivocal, YES, microdrag exists. For me there cannot be any other answer. The logic goes like this. Drag exits. The further we are from an event, the more difficult it is to see. Eventually, there comes a point where either the drag is too small or we are too far to see it. Therefore, by deductive logic alone, micro drag exists, just like there are other things in this universe that exist that we cannot see. Micro drag, in my view, is like the wind. We cannot see it but we can tell it exists by its effect. That is my answer to your first question.
Your second question is, "how are you to determine if micro-drag is there and correct it if you can't see it?"
If deductive reasoning is not sufficient for you then experimentation is a second method. What experiment then tells us that micro drag exist?
Everyone that that fly fished for any length of time has had the situation that we saw visible drag and either lengthened our tippet, gone down in tippet size, or done both and the fish then takes the fly; and we simultaneously notice that the drag is no longer visible. So that tells us that a longer tippet and a thinner tippet will reduces drag when we see it; and by extension of that theory, should reduce drag when we cannot see it (the micro drag that was proven in the paragraph above).
This is confirmed when we apply this theory when we suspect that there is drag that we cannot see (micro drag). I have and I suspect you have been in the situation where we suspected that there is micro drag, put on a longer and thinner tippet and the fish takes a fly that it has refused in previously. This happens often enough to me that I am confident that micro drag exists both by pure deductive reasoning and experimental confirmation.
This answers your second question as to how we can know micro drag exists even when we cannot see it. We cannot see micro drag, but the same solution that applies to drag we can see, cures a problem that we cannot see. The logical conclusion is that if the cure is the same, the problem must be the same. You could protest there could be something else going on that a longer and thinner tippet cured BUT by Occam's Razor (Entities should not be multiplied unnecessarily), we need not postulate anything else.
Your final question is more difficult. Since there was no solution, one cannot be absolutely sure what the problem was. It could be something else.
You have suggested other possibilities like a masking hatch, rise form differences, etc, that could be causes. But evidence for those things can be evaluated and discarded by doing the things you suggest. A key truth is that the suggestion of other possibilities does not disprove the truth of the original theory, it only makes proof more complex.
A knowledgeable fly fisher would have evaluated for other causes of the refusal, AND if that same fly had taken other fish in reasonable proximity in time and location to the refusal; Occam's Razor will conclude that the most likely cause is micro drag. Since the fly has been tested, and other possibilities have been discarded as the likely cause of the refusal, what we are left with is micro drag as the most likely cause.
"Discovery consists of seeing what everybody has seen and thinking what nobody has thought"..........Szent-Gyorgy