Why, on such a lovely day, not demolish some theories about subjectivism, especially when they objectively represent obscure understanding of science and Marxism?
It’s always a pleasure, although it’s a waste of time.

I'm going to touch on some of the basics of what you assort your thinking.

That’s not true, when two scientists debate phenomena of physics; they try to challenge one another’s theory by showing that one of the theories does not correspond to reality. For a long time people thought that light was made out of particles, a minority of scientist, however, argued that light is made out of waves. This debate came to an end by shining a beam of light into an obstacle and seeing a spot of light directly behind it, as predicted by the wave theory but not by the particle theory. Even the contradictions that exist between the Bohr and Bohn regarding quantum theory, is going to be resolve in an experimental way. Scientific theories do not just peacefully coexist, scientist through experimenting with reality try to prove their correctness or falseness.
Marxist would not deny the influence of the Enlightenment Movement, but would rather try to understand how the Enlightenment movement came did about to began with. To disconnect the enlightenment movement from new scientific discovery of the time, to the changing of the economy that gave rise to different ideas such as privet property (and how this leads to happiness) or individual human rights, is to not understand the Enlightenment movement at all.

This is such a reductionist way of looking at things, and I suspect that you got your ideas from Locke. You deny that there are different levels of complexity in phenomena. The physicist would actually say that what you call colors are sensation that are produce by different kinds of waves. The waves are out their, the sensation is in your mind. If one has jaundice one will see things as yellow. The waves are objective the perception is subjective.
The Marxist understanding of history is not one that disregards events, people, and ideas but one that understand that the deep currents driving the swirls and eddies that are on the surface of the river (to borrow a quote from Hegel). Things can be an expression of other phenomena and still be real.

You are again using vulgar reductionism by assuming that every theory can be reduce to physics (or any other science), or that by knowing physics one can understand human psychology (when both are true). There are different laws operating in different systems. As a fact, a physicist would argue that when you have enough complexity, qualitatively new physical laws arrive that are not predictable.
Western medicine might have some understanding of human bodies and Chinese others. Some truth about acupuncture is being verified by the study of bio-chemistry. In other words different sciences need to be consistent with each other, but not reducible to each other.

Really? Where did you get that from? That would be news to me, Marx, and scientists who lived centuries before Marx. Long before Marx scientists understood that in order to know the world you need to change it. Has happens in any experiment, you change certain conditions in order to discover what happens. Marx statement was addressed at philosophers.

What a bunch of bullshit. Marx discovered in a very concrete and detailed way what drives capitalist economy and expanded the understanding of dialectical materialism. He never argued that knowledge is limited to phenomena or facts or obtain only by the scientists. Marx succeeded in finding the underline dynamics driving society.
The Frankfort schools were subjective idealist; they want back to the utopian socialist that preceded Marx, they definitely did not took a step forward.And how does post modernism as a whole has any relation to stopping oppression?

Right, elephants don’t come up with theories. The question is can theory be tested in reality? Can the reality out there be tested through practice and modified?

You are flying very free with your definition of theory. Sure people can use different modes of thinking to navigate their life, are we discussing the unscientific way in which people behave? What “works” for us? Or how to define what is scientifically true?

A theory in a scientific sense is a model of reality and the objective laws that govern it (obviously independent of the human that discovers it). If the scientist desires to get from A to B and it does not correspond to reality, the theory is not true. In other words, Pragmatism is not Theory. Furthermore, things that are not true can work temporarily, one who managed to heal from a terminal cancer because of a belief in god, did not heal because of god, but because of some placebo affect. You can’t really understand the phenomena of cancer by assuming that people might heal by believing in god, you can understand it by scientifically researching why the placebo affect can help sick people.

It seems that you obscure so many facts, in order to get to your subjective “truth”, why? Is this is your example of A to B? Is the end (subjective reality) justifies the means (misrepresenting science and Marxism)? Why negate history like this? Isn’t this what Popper would call Historicism?
Speaking of, who can forget this great “refutation” of Marxism:

“There are countries, for instance the Scandinavian democracies, Czechoslovakia, Canada, Australia, New Zealand, to say nothing of the United States, in which a democratic interventionism secured to the workers a high standard of living, in spite of the fact that colonial exploitation had no influence there, or was at any rate far too unimportant to support the hypothesis…. Furthermore, although the misery imposed upon the natives through colonization is one of the darkest chapters in the history of civilization, it cannot be asserted that their misery has tended to increase since the days of Marx. The exact opposite is the case; things have greatly improved. And yet, increasing misery would have to be very noticeable there if the auxiliary hypothesis [about the effects of colonialism and imperialism] and the original theory [of Marx] were both correct.” (the Open Society and its Enemies, Karl Popper pg 206).

Yes, the people of the Third World should stop dying from starvation and preventable disease while being exploited by the west and get down with Popper’s theory.
Maybe their physical lives are just their subjective reality that can be transformed into Popper “greatly improved” theory of the third world.

Is this is one way to look at reality, or is this a false theory?

I’m not going to answer comments, assuming that this post is not deleted, apologies for not having enough time to mention Palestine.