I am sure Randi exposed lots of charlatans, and my point is not to defend them. There are certainly lots of charlatans in those fields. There are charlatans everywhere, even in science.
My point was that no sensible person would take on Randi's offer, because ultimately you need to claim that something that cannot be measured can be measured. And that is not possible, because not everything can be measured. And those things that can be measured, would not be "paranormal" by Randi's standards.
I never said that there are no measurements for certain aspects of quality. If you care to look, you can see measurements even for certain aspects of things Randi would call paranormal. For example, there have been found measurable neurological changes in people who engage in certain kinds of meditation for extended periods.
But those aspects are consequences of the thing, they are not the thing itself. I don't see it very useful to argue about this. If you do not see that there are things that cannot be measured, we will not get much further in this discussion. And we we are already way too much on a tangent here anyway. Thanks for the discussion.
The people Randi challenged were goalpost movers. They claimed pretty wild things until challenged, in which case they didn't like it and didn't accept the challenge, or argued they didn't really claim what they had claimed (often on record).
He merely asked them to demonstrate the powers they claimed they had when duping people. Is that "measuring"? Why, if you claim you can move a spoon with your mind, or read other people's minds, or that you can predict the order of Tarot cards, is it unfair to ask you to demonstrate in an environment not controlled by your confederates? Is that "measuring"?
I think Randi was right, and Tarot is a swindle.
Scammers and swindlers attacked Randi as a person when they really should have put their... um, powers where their mouth was and shut Randi up by demonstrating what they claimed. A neat prize awaited them! Of course, no-one ever claimed that prize because it's all bullshit.
> But still, nobody can define objective measures about quality.
This isn't true, there are tons of metrics about quality. In software it can be fewer that N bugs per M lines of code, or whatever. For knives it could be sharpness and lack of brittleness (measured). For airplane models it could be fewer than N crashes per decade or whatever.
More importantly, fringe pseudoscientists made actual measurable claims and only backed out when Randi warned them he would monitor the demonstration and bar any confederates from messing with it! So there's no "trick" except that of those refusing those very fair conditions.