Merriam-Webster Collegiate Dictionary - antinomy

 noun  (plural -mies)  Etymology: German Antinomie, from Latin antinomia conflict of laws, from Greek, from anti- + nomos law — more at nimble  Date: 1592  1. a contradiction between two apparently equally valid principles or between inferences correctly drawn from such principles  2. a fundamental and apparently unresolvable conflict or contradiction antinomies of beauty and evil, freedom and slavery — Stephen Holden  • antinomic adjective