rectangle vs. square

[Jim Parish]

Arnold Zwicky wrote:
> maybe implicature would be at work for someone -- is there such a native speaker? --
> who somehow learned the technical uses (of "ellipse" and "circle", of "rectangle" and
> "square") before the ordinary-language uses.  but for ordinary speakers, "circle" is not
> a special case of "ellipse", nor "square" a special case of "rectangle", period; that's
> the way you learn to talk when you learn to "talk geometry".

And yet this discussion began with Wilson's complaint:
> Has it become the case that a "square" is no longer considered to be a
> kind of rectangle, whereas a "rectangle" can be only an oblong?

which I take to mean that, at least for *some* speakers, "square" was a special case of
"rectangle" at some point in the past. It is probably true that, as you say, for most
present-day ordinary-language speakers, this is not true; the explanation via implicature
might at least provide a mechanism for a change in meaning.

I take your point about the technical use of ordinary words. I might quibble about the
sequence of events; "rectangle" and "ellipse" *originated* as technical terms, but
synchronically that's irrelevant. A more interesting example is the mathematician's use
of inclusive "or"; Boole's original work used the exclusive "or", until DeMorgan persuaded
him that the inclusive "or" made for more elegant results. (I know there's been some
discussion of inclusive vs. exclusive "or" on the list, but I can't seem to find it in the
archives. Was there any resolution of the question of the meaning of ordinary-language
"or"?)

Jim Parish

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