Miners reaching agreement via POW or POS seems to be another M of N system based on competition.  This may be the best possible method of preventing "viruses" and being fault tolerant (via parallel checks) at all levels in this new technology, from individual contracts, to setting value (bidding on exchanges is a competitive M of N algorithm), to verifying the blockchain.  There seems to be no way of preventing "viruses" in computing systems that have the ability to evolve, so that core developers making unilateral and key decisions may always be needed.  They themselves are a competitive M of N system of evolving algorithms (brains).  Pattern recognition also uses a nested hierarchy of M of N competitors.  Life evolved patterns that "recognize" survival in this way from base pairs to triplets (amino acids) to proteins to cells to organs to bodies to species to ecosystems. Competitive evolution occurs at every level, not restricted to the "gene" level. Notice the lowest level stays around the longest without changing.  The mid-level changes the most rapidly.  The internet protocol has been the lowest level for copyable "public" bits and has survived well. The bitcoin and ethereum protocols for these amazing uncopyable "private" bits need to find agreement at some point (and maximum simplicity) before the marriage between the public and private bits can occur.  The ultimate goal for humans that want to engage with these systems is a better marriage between individuals and society for the benefit of both.  All for one and one for all, contractually defined, discovered, and enforced.  What else is society good for if not to reward individuals via various (crypto)currencies (political, financial, social currencies) according to various hierarchically nested competing sets of (crypto)contracts that together constitute a (crypto)governed-economy?  Each fixed-quantity currency represents the total value of the societal asset(s) that the governing set of contracts are competing to re-distribute among the citizens that have joined that governed-economic system.  Anarchic privacy may not be the most important end goal as Zerocash et al could achieve. Provable identities within the governed system might remain anonymous to others in the system, but not to the system of contracts. This might be a key to everything we want as social creatures.  Absolute anonymity is required by those wishing to profit without regard to the cost to society as a whole.  If we keep the system perfect and pure, the economic and governing systems that evolve from this internet-"bitcoin" marriage will not view humans any different from any other intelligent agents on the system. Humans are outdated. Companies are working fast and furious to replace them with machines. If our governing system becomes pure without regard to human status (and thereby eliminate many things from welfare to war), that desire to replace humans with more efficient machines can become system-wide.  Photosynthesis is 100 times less efficient than solar cells. The current 6th great extinction of episode we are in will continue as the biosphere is replaced with machines.