Glutton for punishment seems appropriate to opening this hornet's nest, yet there are fresh things to say, so why not?
Double blind testing simply refers to the notion that neither the subject nor the tester knows which they are reviewing. The idea is easy enough. If neither knows whether A or B is being chosen, then any possibility of bias can be removed. A safe test that makes logical sense. Yet, while this methodology may be valid for some things, I would propose it is not for others.
In medicine a placebo is often used and sometimes found to be as effective as the drug under trial. When this happens, researchers typically negate the drug's efficacy; if it is only as effective as a sugar pill, it must not be effective at all. Sound reasoning, but not entirely valid. Why? It ignores our complexity. Doctors, as well as audio engineers, tend to fall into traps set by our belief in hard boundaries of understanding. We put up fences of If/THEN statements without regard to peripheral realities. For example, we know there are people who can raise and lower their personal blood pressure levels mentally; like the click of a switch, or the swallow of a pill. But most of us can't and we need drugs that work without our mental assistance or belief that they do work; they work even if we aren't aware they are in our bloodstream. And so we label those as effective. Placebos, even those that work, are labeled as not valid. That is a narrow point of view.
What if doctors perfected a blood pressure placebo strong enough to work on most people; those with strong enough minds and beliefs to have it work? Would that not simply suggest there is more going on in our physical machinery than the tests that labeled it a placebo allowed for?
I am not suggesting magic, nor am I suggesting what we as Audiophiles hear, that others refuse to recognize, is a placebo or artifact of imagination. Quite the opposite. I am suggesting that test methods, even cleverly devised ones, rarely cover a large enough scope to be accurate and double blinds, of the type Audiophiles correctly label as wrong headed, are just that.
Tomorrow we dig deeper.