Same question, only substitute agency for properties.
I think only this second question was directed towards me, but my response to it should tell you how I would answer the other two questions as well. My answer to this second question is “yes.” Agency exists independently of my or your or anyone’s conceiving of it.
Here’s a parallel question: is causation real? Hume gave us reasons for doubting that it is—for thinking that it was just a projection of our mind’s custom or habit of expectation onto the world. Of course accepting Hume’s skepticism depends upon accepting his premise or starting point—which is the starting point of Descartes as well as his empiricist opponents—viz. that all we are directly aware of are our own perceptions or ideas and we must make inferences based on these (internal objects) about what the external world is like. And, notoriously, none of these inferential leaps are guaranteed certain—there’s always room for doubt about them. Essentially, if one adopts this starting point (of the theory of ideas), then nothing is really “real” except the inner life of your own mind. Thus everything is cast into doubt and a radical (and unworkable) skepticism inevitably follows.
Why do I think that agency is real? Well, for one thing, we’d be seriously deluded if our agency was just an illusion, right? If, in “reality,” we never did anything, but stuff just happened to us as a result of some cause or chain of causes completely outside of our control, yet we felt as if we were the author of our own actions, we’d be seriously deluded. What consideration could possibly be so compelling that we would be willing to accept that we are in fact completely deluded? What thought or assumption would lead us to cast doubt on something that seemed so obvious and natural? In my view, the assumption that leads to such a doubt here is an unflinching acceptance of extreme reductionism. If we accept the worldview which tells us that “Reality” (capital “R”) is just atoms-in-the-void and nothing more—that everything can and must be explained in such terms, then not just agency but a good deal more is going to turn out to be illusory. Is love real; is hunger or thirst real; are markets real? Not if we accept this extreme form of reductionism! When you look through a microscope is what you’re seeing “more real” because it is smaller or somehow more fundamental? We know that desks, chairs, and everything else is ultimately composed of certain arrangements of atoms. Does this mean that desks and chairs don’t “really” exist? What’s more, since we now know that atoms are not the most fundamental particle are we led by the same logic to question their “reality”? Nobody has ever even seen one of these sub-atomic particles yet we’re supposed to accept that that is what reality ultimately is?
What about planets, solar systems, galaxies? A planet is composed of many complex subsystems that can be broken down and isolated for the purpose of study. For example a planet may have an atmosphere, satellite(s), topography, a crust, a core, etc. And each of these systems, if you want to break it down even further, is divided into subsystems, which can again be divided into parts and then into molecules, atoms, particles, etc…(who knows where it will end?).
The mistake here, in my view, is to assume that only one branch of science has the exclusive right to the adjective “real.”