rectangle vs. square

[Jim Parish]

Dan Goncharoff wrote:
> Second, what would be the justification for using "ellipse" when describing
> a circle, or rectangle for square? It may be correct, but it's not
> informative.

Precisely the point. *As terms* "ellipse" includes "circle", and "rectangle" includes
"square". (Trust me on this: I'm a professional mathematician, specializing in geometry.)
But to use "ellipse", referring to a circle, is misleading; by the usual conventions of
conversational implicature, the failure to use the more specific term invites the hearer to
conclude that the more specific term does not apply. In other words, *semantically* the
word "rectangle" applies to squares, but *pragmatically* it almost never will. (I might use
it that way, but mathematical language deliberately defies the conventions of
implicature.)

Jim Parish

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