There are at least 3 ways for anti-reductionism to be not only clearly consistent, but with some plausibility, true - in the sense that there is empirical as well as conceptual evidence for every position (This is connected to a quote I posted yesterday):

• Ontological monism: The whole universe is prior to its parts (see this paper)

• No fundamental level: The descent of levels is infinite (see that paper)

• "Causation" is an inconsistent concept (I'm one free afternoon and two karma points away from a top-level post on this ;)