blueSky wrote:In this context, is bohr argument sound according to you? And if not, how?
I am not familiar with the Bohr quotation, except as presented by
fresco. I'll assume, therefore, that the quotation is both accurate and a genuine reflection of Bohr's beliefs. Here, again, is what he said:
We customarily think of the outside world as separate from ourselves, and the boundary between the two is the surface of our skin. However, think of a blind person who gets around with the assistance of a cane. In time that person will probably treat the cane as part of his or her body, and will think of the outside world as beginning just at the tip of the cane. Now imagine the blind man's sense of touch extending out of the tip of the cane and into the roadway itself. Imagine it extending further, down the block, into the countryside, to the whole world. There is no point where the blind man ends and the world begins. Similarly, we can not say which is the system and which is us observing it.
It's a charming metaphor, but Bohr has really set out a rather unconvincing
sorites paradox.
Sorites is the Greek for "heap," which gives an insight into its nature. Suppose we take a heap, composed of peppercorns. Take one peppercorn away, and the heap remains a heap. Take another away, and we are still left with a heap. Thus, we can assert that taking away a single peppercorn does not make a heap a non-heap. But if we keep taking away one peppercorn at a time, we are eventually left with a single peppercorn. So we either must conclude that a single peppercorn is also a heap, or else that there is some point at which subtracting a single peppercorn transforms the heap into something else.
In the same way, Bohr extends the reach of the blind man. If his sense of distinction between himself and the outside world can be extended to his cane, then it can be extended to the sidewalk. And if it can be extended to the roadway, it can be extended to the countryside, and thence to the entire world. But this is merely the heap in reverse: if adding the cane to the blind man's sense of self doesn't make any difference, then adding the roadway doesn't make any difference, and adding the countryside doesn't make a difference,
ad infinitum. That may work on the metaphorical level, but it's hardly convincing logically, since there is no real reason to accept even Bohr's first premise: i.e. that the blind man cannot distinguish between his can and himself.**
On the larger level, there is no reason to think that Bohr jettisoned the distinction between subject and object in his work as a physicist, since it would be impossible to make any kind of scientific conclusions based upon an
identity of the two. If all I see is all I am, then all of my conclusions are bare assertions, nothing more. One would be living in the land of
ipse dixit,* not in the realm of science and reason.
*and old times there are not forgotten.
**EDIT: that should be "cane," not "can." As far as I know, the blind man would still be able to distinguish his can from, say, a hole in the ground.