Based on this, I strongly feel that the “RNA-world” is an arbitrary, unphysical assumption advanced because of the view that reproduction is the only necessary criteria for living organization and that it is something which molecules do "in their own interest." Molecules have no such thing, and a chemical cycle which copies RNA sequences for no other purpose than to make more RNA sequences will never produce enough entropy to command any significant energy flux in a prebiotic chemical environment. An even simpler critique involves asking on what basis it would be possible to segregate “RNA” from the amino acids, lipids, and sugars which would also have been spontaneously produced in the prebiotic soup. Nature, after all, doesn’t know anything about our organic molecule classification scheme. Given the fact that proteins and nucleic acids *do* spontaneously stick together, as in the transcription complexes necessary to copy a DNA sequence, I see no reason to assume they weren’t stuck together from the beginning, along with the lipids which would have spontaneously assembled into membranes the moment they were sufficiently concentrated, or “as the soup thickened.” Most importantly, as a theorist attempting to explain the spontaneous formation of a complex phenomenon, why arbitrarily restrict oneself to a limited subset of organic possibilities? Why not give oneself access to the full range of chemical possibilities of which we know nature to be capable?
At any rate, organisms are closed cycles of material transformations that require energy flow to operate. They are constitutionally circular, based on a logic in which DNA sequences are used to build proteins which in turn copy and modify the DNA sequences. Intelligent design proponents often use this fact to argue that life is too complex not to have been designed. The truth, which we see everywhere in nature, is that cycles emerge and grow spontaneously, are selected for persistent existence through the amount of energy they pull into themselves, and they "process this energy" (produce entropy) in the service of the randomizing directive of the second law of thermodynamics. Understanding this rationale for the existence of organisms begins to lay the basis for unerstanding the thermodynamic and informational driving forces which form the physical basis of evolution.
