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jibalt | 2 years ago

> Ah, but in a circle the circumference is always equidistant to the centre, which is never true of an ellipse.

It's never true of an ellipse that isn't a circle. i.e., this is a--ahem--circular argument.

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DiscourseFan|2 years ago

You can't just decide that the circle is contained in the set of all ellipses. Anyway its a philosophical argument, you can't "prove" mathematically that circles are ellipses or vica versa.

Why do circles need to be ellipses anyway, why can't they be absolutely different? If they were absolutely different, then circles would be purely ideal, and yet an organizing principle (or as the say in Greek, an ἀρχιτεκτονική, from when we receive the word architecture). The only way to understand this, ontologically, is if we take the world to be in a constant tension with the "earth," as Heidegger puts it (cf. The Origin of the Work of Art), the thing in which the "rifts," which is the actual discourse of idealism, come about.

You know, I thought about it for a moment, and I don't think the visual circle is even universal. The schema of the circle may be, but the circle itself never appears. See this article below[0].

[0]https://en.wikipedia.org/wiki/Molyneux's_problem

trealira|2 years ago

I'm not who you replied to, but the reason circles are ellipses is because the definition of a circle is equivalent to the case of an ellipse where both foci have the same x, y coordinates. You can read about all the definitions of an ellipse on Wikipedia.

https://en.wikipedia.org/wiki/Ellipse

Functionally, they might not be the same if you're programming them. For example, if you have a circle class with members detailing its center and its radius, it might be more efficient to draw an instance of it than an instance of an ellipse class that has two foci members that just happen to have the same values.