Yes. As Wittgenstein used to say to his students before they entered the lecture hall, "Please do not leave your brains on the rack with your hat".

Yes. I'm afraid I'm often guilty of such a thing, and likely will be in the future. I hope you will continue to point out when I do, as I would prefer to stand corrected than sit comfortably in ignorance.

O.K. But I am not infallible. None of us are. All we can do is to be tough on our own beliefs.

Thank you. This is what I'm trying to learn to do. The one philosophy professor I had many (many) years ago in college did not take this approach.

This is actually a semi-debate in physics. Whether the physical theories are reality or an abstraction of reality. It seems physics gets to the point where people are confident to say it is concrete, but then we create new experiments that defy existing theories and start over again, thus leading back to the idea of abstraction.

The issue here is partly dealt with by Bradley in his essay Appearance and Reality. If we examine the psychophysical phenomena of the spacetime world it proves impossible to show they are real. Rather, logical analysis shows that they cannot be real. They exist as appearances but have no substance. Bradley proves this, and it is the justification for his Absolute Idealism. For this every phenomenon except one is not really real, and this would be Bradley's Reality.

Perhaps it would be about right to say that mysticism is a bridge between appearance and reality.

But how do real and really real differ? Real diamonds are real, but are they really real?

Good question. I've tried to answer it eight times already and can't get it right. Regrettably I can't answer it properly from experience.

There would be a unconditioned phenomena from which the spacetime universe, including 'selfs' like you and me, is emergent. Not long ago in past but right here and now and in every moment. This would be Parmenides and Aristotle's unchanging substance, Bradley's 'Reality,' Hegel's spiritual unity, Kant's subject of rational psychology, Lao-tsu's Tao, Schroedinger's blank canvas etc. Everything else would be Maya, the Matrix, Samsara etc.

There would be no possibility of mistaking the real for the unreal, but every possibility of doing the reverse. Mysticism would be the pursuit of the former.

Iron Sulfide looks like gold (it is called, "fools gold"). But in reality it is not gold at all

In the reality of a "fool," it is "gold." That's why many people have been "fooled" by it! (Ask Bernie Madoff if you don't believe me.)

Why would anyone believe that because he, or someone else, cannot tell the difference between what is real, and what is fake, that there is no difference, is something I don't understand. He would be making his own ignorance into a standard for others.

If (s)he's a "fool", how would (s)he know that (s)he, or someone else, "cannot tell the difference between what is real, and what is fake"?
People do "foolish" things all the time, like vote for Bush and Cheney, twice! (I hope you weren't one of them.)

Someone would have to be very foolish not to know that no one can tell the difference between counterfeit and real ... He might even be put away

Of course, theories are abstract. What else would they be? (I do not know what you mean by saying that a theory is concrete). But why would the fact that a theory is repudiated by facts, make it abstract? But then, I don't really know what you mean by "abstract" and, "concrete". I use the term "abstract" to mean the absence of location in space and time. So that numbers are abstract entities, but stoves are concrete entities. And theories are, of course, abstract entities. They do not have spatial or temporal location. (Where would molecular theory be located?).

In general the term abstract in science is "an idea or term considered apart from some material basis or object." from dictionary.com. And here is a good article on it as well Abstract object - Wikipedia, the free encyclopedia . So the debate is whether scientific theories are concrete (thus are ingrained in reality). Like the Coulombic force is an intrinsic natural property of charged particles or it is just a convenient categorization for the human mind, if it could be better represented by another set of theories. One of the interesting issues that happen is when new theories arrive, often the categorizations are redefined. For example the Kelvin temperature scale was considered absolute in thermodynamics, which means no going below zero. But when Boltzmann developed statistical mechanics the Kelvin temperature scale was redefined and now it can yield negative temperatures in what they call two-state systems.

A theory may be about what is concrete. But that does not make the theroy itself a concrete object. You have to distinguish between what the theory is of, and the theory itself. Theories are, themselves, abstract objects.

You can find several examples of "concrete abstracts" here!

A theory may be about what is concrete. But that does not make the theroy itself a concrete object. You have to distinguish between what the theory is of, and the theory itself. Theories are, themselves, abstract objects.