Bear with me

So I'm studying madly for the test-that-shall-not-be-named, and I'm spending an inordinate amount of time trying to understand the difference between necessary and sufficient conditions. In the King's English, this is an "if then" statement. The thing that flummoxes me is that they are not reciprocal. If A, then B is not the same as if B, then A. If it is 95 degrees outside, Michelann is grumpy. But if Michelann is grumpy, it might be 95 degrees outside, but Michelann may be grumpy because Loki ate her shoe (for reals), or some other reason unrelated to the temperature.

If Michelann is not grumpy, then it is not 95 degrees outside, but if it is not 95 degrees outside, Michelann might still be grumpy. This is called the contrapositive. It makes a kind of sense in the real world, but it's really hard to tease out of statements with quadruple negatives and slithery double-speak. Trust me.

Then something occurred to me today. Remember how I mentioned the Platinum rule? Do unto others as they would have done unto them. This is just a recommendation, it's not reciprocal and it doesn't predict an outcome. I like it from an ethical standpoint because you don't assume everyone is just like you. But the Golden Rule is a little different. Observe.

"Do unto others as you would have done unto you."

From this comes the assumption that others would like to be done unto as you would. So:
If I want a pony, then everyone wants a pony. According to the laws governing necessary and sufficient conditions, the contrapositive says that if someone else doesn't want a pony, then I must not want a pony.

MWP(me want pony)---> OWP(others want pony)
OWP ---> MWP

And this is obviously not the case. Just because someone else doesn't want a pony doesn't mean that I can't want a pony. Hence my preference for the Platinum rule.

And Loki really ate my shoe. But I'm not grumpy.