Good Definitions

A good definition of X is one that agrees with the cases we feel sure about as being X or not and helps us decide cases we are unsure about. A good definition of X is one that explains why something is an X.

"Planets are large objects" is a bad definition because suns are large objects but not planets.

"Sleeping pills are pills that have a sleep inducing effect" is a bad definition because it won't help us decide cases we are unsure are sleeping pills.

"What is right is what God approves of" is a bad definition, according to people in one of Plato's dialogues, because God approves things because they are right; they aren't right because he approves of them.

Why would Plato object to this definition:
Good shoes are ones that people like.


How would Plato define a social website?
How might he define what a good social website is?
What might he say are qualities that will make a social website a good one?