aaaaand there is my answer.

I think I struggle with the distinction between VALID arguments and TRUE arguments. If the Superset of "Ninjas" includes a subset of "Turtles", which includes "Donatello" then the argument is valid that donatello is a ninja, but it is not true that all turtles are ninjas. For the the argument to be both valid and true the subset would have to be TMNT.

Well, I got that about as wrong as one could!