Responding to Shapiro's harsh criticism of the “RNA first” theory and his proposal of the “metabolism first” scenario as a more likely approach to a naturalistic origin of life:
Theories of the origin of life based on metabolic cycles cannot be justified by the inadequacy of competing theories: they must stand on their own...solutions offered by supporters of geneticist or metabolist scenarios that are dependant on "if pigs could fly" hypothetical chemistry are unlikely to help."
