Rudyard Kipling, "If And Only If"

Iff you can keep two premises in view
In every proposition, and not bodge it,
Iff you can carefully derive the true
Via both sides of biconditional logic;
Iff you can frame precisely all you state,
Distinguish logic from the vulgar fable,
Step cleanly through the XNOR gate
Lay placemats on your P ↔ Q truth-table;

Iff it's both necessary and sufficient
That you out-logic all your math-opponents;
Iff their old inference proves inefficient
Beside your à-la-mode, dense modus podens;
Iff you unpack the statement “P iff Q”
As “if P, then it's Q” and “if Q, P”,
or as “if not-P, then not-Q” linked to
The “if P, then Q” prior necessity;

Iff you draw Euler digrams to show
How logical relationships obtain,
Not caring that you bore both friend and foe
With such mathematical legerdemain;
Iff you define the unforgiving minute
As sixty seconds squeezed of all their fun,
Yours is the Math and everything that’s in it!
And—one thing more—you’re on your own, my son.