Originalism is the belief that the U.S. Constitution should be interpreted according to the intent of those who adopted it.
My theory: The whole originalist project, with its fetishizing of the thoughts of long dead men, is nothing but a mechanism for imposing regressive values on the American people.
Antonin Scalia doesn't really care what the ratifiers thought. We know this is true because when the opinions of the ratifiers and his own ideology don't coincide, the ratifiers are abandoned. (see Bush v. Gore) For Scalia, originalism is a tool, used cynicaly.
Anti-originalists also interpret the constitution in a way that is informed by their ideology, but they, at least, have the virtue of being honest about it.