Objective reality is the reality we directly perceive, everything else is an attempt to explain the nature of that directly perceived physical world. The pictures, models, and metaphors of science are only to help us "grasp" those aspects of the perceived physical world that are otherwise hard to "imagine."
Regi old fellow,
If all we ever ascribed reality to was what we could directly perceive, man would never have come out of the caves. All they would have ever believed in was what their senses immediately conveyed to them. The whole basis of science and philosophy is the idea that there is deeper reality behind the one we currently perceive, and we can use indirect observation and reasoning to determine what this reality is. The purpose of science and philosophy is to understand and explain *reality*, not restrict our conception of reality to things we can directly observe.
Here's a very simple example which conveys the point: Ask someone who has never been to Egypt what the Great Pyramids look like. Chances are they know. But how? After all, they have never directly perceived the pyramids with their senses. Instead they know through *pictures* they saw in books or on T.V. But should this disqualify their knowledge? Of course not. They are justified in believing that there is a *correspondence* between the pictures of pyramids and the pyramids themselves because of their rational *understanding* of where the pictures came from.
Similarly, scientists do not need to directly perceive something to ascribe reality to their conceptions. If they have indirect evidence combined with a causal rational understanding, they are entitled to believe that there is at least *some* degree of correspondence between their model of reality and reality itself.
Just because entities are not directly observable now, doesn't mean that science won't find a way to observe them directly at some future time. The famous example here is the atom. Philosophical arguments for these existed from the time of the Greeks, but logical positivists refused to believe in atoms because no one could directly observe them. They ridiculed scientists, saying that 'atoms' were 'just a device' and it was 'reification' to ascribe reality to these 'unobservables'. But lo and beyond, eventually someone invented a device (the Scanning Tunneling Microscope) which let scientists directly observe atoms. If scientists had believed the positivists, progress in chemistry would have ground to a stand-still far before this. Another example is the instance of viruses. No one could observe them at the time they were proposed either and the positivists said that they therefore didn't exist. If the positivists had had their way, no medicinal progress would ever have been made.
It is the grossest of subjectivism, claiming the "real" world is the world as I picture it in my head, not the world we actually directly perceive. It is the denial of Objectivism.
You've betrayed a total lack of understanding about the basic principles of rationality Regi. We sure as heck don't know what will turn out to be observable or not, so we shouldn't made advance judgements about what is and is not a part of concrete reality. the nature of reality is what we should be trying to find out, not limit in advance. It is the grossest of subjectivism to claim that "real" world is simply the world you can directly perceive with your senses at the moment.
Who is the most of a subjectivist: the 5 year old who thinks that the whole of reality is composed only of the things he can immediately see before him in his cot, or the 5 year old smart enough to use rudimentary reasoning to determine that there is a much wider reality beyond the one he can currently observe from his cot?
So, what is the ontological status of kinetic energy, potential energy, and action? Are they "out there in reality"? Or are they mathematical concepts that make the solution of some classical mechanics problems easier? Or is there another choice?
The status of some scientific concepts is indeed unclear. I certainly don't say that all useful scientific concepts exist in concrete reality.
Can you explain, then, why we cannot make the similar argument:
I am pointing to the observed fact that in the real world people are forming concepts all the time, and a conceptual epistemology has proven to be very useful to people. This requires explanation. Then I point out that we cannot make sense of these concepts without the Universe of Forms. No alternative theory explains why these concepts work. Therefore this is strong evidence that the Universe of Forms is correct.?
The difference between concepts and the probabilities is that you can compare a lot of different concrete things, and the concept from them, so you're not justified in postulating a world of Universal forms. For probabilities about unique events how-ever (such as the upcoming Presidential election in the U.S), the given context occurs once and only once so no sense can be made of the probability assignation without alternative universes.
The probability argument for Alternative Universes was not a good example anyway. Too much of an abstract and advanced argument. There are many other arguments for alternative universes. For instance how do you explain the classic quantum two-slit experiment in light of this latest reported version of it?
Very rough description recapping the famous experiment and this latest twist on it: light passes through a screen with two slits and hits the wall behind them. When only one slit is open, the light simply spreads out from that one slit and leaves a continuous bright patch on the wall. But with two slits open, you get an interference pattern on the wall - distinctive bands of light and dark - (the light from the second slit is spreading out and interfering with the light from the first slit).
You can cut down the intensity of the light so that only ONE SINGLE PARTICLE OF LIGHT (a photon) passes through the slits at a time. This latest experiment verifies which slit each individual particle travels through. With only one slit open, single particles pass through this one at a time and bang, bang, bang they each leave little dots on the wall as they hit it. Eventually when enough particles of light have been sent the dots on the wall add up to the continuous patch of light spreading out over the wall you'd see if you'd sent them all at once. No problem so far. But the mystery of course comes about when you open both slits and send particles of light through ONE AT A TIME (so that each time one particle moves through one of the two slits at random). The dots start building up as individual particles hit the wall but eventually THE PATTERN ON THE WALL IS THE INTERFERANCE PATTERN OF LIGHT AND DARK BANDS. Merely open the second slit mysteriously changes the behavior of particles traveling through the first slit. The particles are going through one at the time remember. Nothing in this universe can be passing through that second slit. YET IT IS AS IF A GHOSTLY PARTICLE OF LIGHT HAS PASSED THROUGH THAT SECOND SLIT AND INTERFERED WITH THE PARTICLE PASSING THROUGH THE FIRST SLIT. The only coherent realist interpretation is that particles of light from alternative universes are causing the interference. So because this latest reported experiment verifies that definitely only one particle is going through at a time and determines which slit each particle is going through, you seem to have both the wave and particle aspect co-existing. So I actually think it greatly strengthens the case for alternative universes.