quantum mechanics: Kastner\'s brilliant blog (Introduction)

by dhw, Thursday, July 18, 2013, 14:37 (4147 days ago) @ rekastner

Dhw: A perpetual problem for me in this context is the fact that even if there are objective realities outside spacetime, we cannot know what they are. And so when we come to metaphysical concepts, for example, there is still no escaping the "subjectivist" approach. Yes, there has to be an objective truth, but we have no objective access to it!-rekastner: Wait, you have a hidden assumption in your statement "even if there are objective realities outside spacetime, we cannot know what they are."
Your assumption is basically an empiricist approach to knowledge: the doctrine that one can gain knowledge ONLY through sensory perception. But many philosophers, including Plato and Descartes, disagreed with this. Rational analysis is a key ingredient of scientific theory and can yield advances in theoretical description not available based only on studying sensory observations.
So we can't observe these entities directly, but in fact we can gain indirect knowledge of them based on rational analysis of what we can observe. That's what QM is -- it's a theory of objects that cannot be directly observed. Again, I do address these methodological issues in my book, in particular in Chapter 2.-As usual, we have problems of definition and of levels. The history of epistemology is one long dispute over the criteria for what might be called knowledge. On an absolute level, we can argue that there is no such thing, and that ends all discussion! On a commonsense level, we might say that: "knowledge is information the truth of which is recognized by general consensus among those aware of it". I "know" the Earth goes round the sun, and most people agree (our definition has to allow for minority groups, but must also allow for error, since the general consensus can change). This is knowledge (= intersubjective.) My friend Mr Smith "knows" that God is good, but there is no general consensus on the existence or the goodness of God, so this is belief (= subjective). David Turell and Richard Dawkins as scientists would both claim that their respective beliefs and disbeliefs are based on rational analysis of what they observe. There is no general consensus here either, so rational analysis is clearly not sufficient to guarantee knowledge. I'd be surprised if you and your fellow physicists were all in agreement on the realities that exist outside spacetime, and in the context of metaphysics there is certainly no general consensus. If, then, we wish to talk of knowledge, we must agree on a definition. Would you accept the one I've given?-To clarify my own position, I am totally against the doctrine that sensory perception is the only access we have to reality (a term I prefer, though it's just as difficult to define as knowledge). Most of the experiences that are precious to me have nothing to do with the senses ... love being foremost among them. And although the senses are essential to the experience of music, literature, and art, they are only a channel to a reality that I do not think is sensory at all. Mystics, psychics, NDE patients all experience realities beyond those of sensory perception, and I am not prepared to dismiss their experiences as fantasy. But they are all subjective. I'm told that in your field, "reality" changes with the observer's observation of it. Again, there is no escaping subjectivity, but subjectivity does not necessarily mean unreality! -Now for a special request. Thank you for the various references. I shall try to follow them up as well as order your book, but there's a problem. Time has to be set aside for all these things, and I already have difficulty keeping up with the posts on this forum! I suspect David never sleeps, as he seems to keep up with everything, but I'm a dozy old soul, my days are full, and my nights are long! It would therefore be enormously helpful if we could deal with points as they arise rather than be given a reading list. "Transaction" is obviously a key term for you, and therefore a key term for this discussion (if you are willing to continue it). Can you not define it for me, as in the sentence I quoted last time, or give an example? I hope you will realize from the responses you've already received that your posts are causing a stir among us, and I'm certainly not the only one eager to profit from your expertise, so please don't take offence at this request. It's for purely practical purposes!