Three. One to insist that neither the bulb nor socket be excluded. One to enclude the socketness and bulbness into an integral but merely conceptual harmony. And one to enact the damn screwing in.
Meanwhile, a writer at Integral World will insist that the integralist can only screw in a light bulb by superstitiously positing the metaphysical concept of Eros which doesn’t exist, and therefore it’s much better for everyone just to sit in the dark like they do.
More answers at Integral Agape.