On 11/25/07, Eugene Salamin <gene_salamin@yahoo.com> wrote:
A mirror neither exchanges left with right nor up with down. It
exchanges front with back. This is precisely the definition of "reflection in a plane".
From: "Fred lunnon" <fred.lunnon@gmail.com>
[Not seeing that is] an excellent example of how a badly-formulated linguistic trope may confuse its users so badly that they become incapable of disentangling its distinct meanings, even after those are explicitly pointed out. WFL
From: Gareth McCaughan <gareth.mccaughan@pobox.com>
[...] I'd have added that we think of what a mirror does as exchanging left with right because the things we look at in mirrors -- most notably ourselves, but plenty else besides -- are much nearer to being left-right symmetrical than to being top-bottom symmetrical. [...]
Or front-back.
(There's a *reason* why people commonly think that mirrors swap left and right, which is logically prior to that trope.)
I would say we code for the smallest edit distance, where "smallest" means most likely. So: the image in the mirror is rotated around the vertical axis and flipped left to right. It seems to me that the rotation happens unconsciously (pre-linguistically), and once it has, untangling the rest consciously is tough. Mirrored pairs are called "right-handed" and "left-handed"-- is that the "badly-formulated linguistic trope" you mean, Fred? Or is it the whole treatment of "swap" as a verb, or...?
From: Bill Thurston <wpt4@cornell.edu>
Ultimately, I mellowed. I realized that people were unconvinced by each other's explanations because they weren't actually confused about what a mirror does. There's not an actual question here without words.
Maybe we can't *access* the question without words(*), but I think I was actually confused when I first came across this one. The mirror obviously flips one axis and not the other, and just as obviously can't. There's a real question of how to make sense of it. Motor/perceptual problem: sequences of transformations and outcomes. Math problem: equivalent expressions. Language problem: in practical (as opposed to tact & felicity) situations, once you have one expression to identify a thing, that's usually good enough: you've identified the thing and the thing is what matters. I guess this shows that a practical problem can have the same structure as a felicity problem. (It's a matter of "perspicuity." Check out Craig Swanson's http://content.perspicuity.com/?q=taxonomy/term/487 .) --Steve * "...just ask the axis." --Jimi Hendrix