Full Idea
If it is necessary that, if a triangle contains two right angles, that a quadrilateral has four, it is clear that the cause of this is that a triangle has two.
Gist of Idea
The two right angles of a triangle necessitate that a quadrilateral has four
Source
Aristotle (Eudemian Ethics [c.333 BCE], 1222b31)
Book Reference
Aristotle: 'Eudemian Ethics I,II and VIII', ed/tr. Woods,Michael [OUP 1992], p.21
A Reaction
We would not normally use the word 'cause' for this, but 'necessitates' seems to fit, and I like the word 'determines' (because it can be both physical and abstract). An example of what I think of as an Aristotelian necessity maker.