 The New Principle is, Lewis argues, consistent with the best systems theory of laws and chances. Lewis had originally thought that any specification of chance had to be consistent with the Principal Principle. But in later works he argued that the New Principle was a close enough approximation to the Principal Principle that a theory of chances consistent with it was close enough to our pre-theoretic notion of chance to deserve the name. So he could, and did, happily endorse the best systems theory of laws and chance.