[refurb]

Exceptions to a rule are just that - exceptions. They don't refute the general rule.

I might draw a hand with a thumb and four fingers. The fact that some people are born with more or fewer fingers doesn't change the fact I drew a hand.

[becquerel]

Those people still have hands.

[refurb]

Right, but we don't look at someone who was born without a hand and say "ok, clearly our definition of a hand is wrong."