文/长铗
这篇文章英文版发表在《BitcoinMagazine》上，这是一个开始，以后会有越来越多的巴比特作者在BitcoinMagazine上发表文章。巴比特不再满足于将国外资讯单向译介到国内，以后还将向国外比特币社区传播更多来自中国的声音。感谢长人同学的精彩翻译！
比特币网络穷兵黩武的“军备竞赛”引发了人们对其公正性的担忧，在比特币诞生之初，任何人都可通过家用电脑轻易的挖到比特币，中本聪的早期合作者哈尔芬尼回忆，那时候他用电脑挖矿，在几个星期里就开采了几千个比特币。但现在，比特币成了拥有AISC等大规模集成电路的大型矿业公司或专业矿工的“私矿”，这不公平。人们还担心比特币集中在少数人手里，不利于比特币的推广传播。但是科斯定理却认为，在交易成本为零或者很小的前提下，只要财产权是明确的，那么无论起初将财产权赋予谁，市场均能实现资源配置的帕雷托最优。如果起初合理的设定财产权的归属，那么整个系统也将是公平的。
中本聪在设计比特币“挖矿”机制时确实经过了一番考量，他面临两种选择，一种是将比特币按节点数分配给所有比特币用户，即一IP一票，一种是将比特币按计算力分配给矿工，即一CPU一票。出于对比特币网络安全性的考虑，他选择了后者。在白皮书中他写道，“如果是用节点数即IP地址的多少来决定谁是大多数，即一IP地址一票，那么拥有分配大量IP地址的权力的人，比如僵尸网络，就有可能主宰比特币网络。”矿工处理交易数据获得比特币奖励，这固然可视作一种激励机制，但也可以反过来看，比特币作为一种公共资源，被矿工等少数人占有，他得付出计算力，由于比特币网络的安全性正比于全网计算力，所以被征收的计算力被巧妙的应用于全网安全性的保障之上，使得普通用户不需投入计算力就能享有安全交易，这对于用户与矿工双方来说都是公平的。
虽然协议规定了比特币的最初分配，而市场却决定着最终分配。用户拥有向矿工征收“计算力”的权利，那么，他们就可以出售这一权利，即由矿工向用户支付“计算力”，以换取区块内的比特币的所有权；反过来说，矿工拥有获得区块内的比特币的权利，他们可以向用户出售这一权利，即用户从矿工那购入比特币，以换取不需投入计算力就能获得比特币的权利。如果矿工支付的“计算力”高于挖矿收益，他们将减少支付“计算力”，相应的，如果用户购入比特币的费用高于挖矿成本，那么会有越来越多的用户投入挖矿，最终，市场会达成均衡，实现计算力与比特币的高效配置。
比特币诞生之初，转账成本几乎为零，一些特殊用户可以利用小额转账来实现某种目的，比如维基解密以批量小额转账的方式，在区块链中编码一些秘密文件，中本聪骰子等博彩网站则用小额转账来通知用户输赢，甚至发送广告，这让本来就很臃肿的区块链不堪重负。显然，那些频繁使用小额转账的用户占用了大量公共资源，对他们征收交易税（转账手续费）是必要且合理的，这种类似于庇古税的设计，可以大大减少垃圾交易，使得交易的私人成本与社会成本相一致。
比特币的交易税征收规则可谓是锱铢必较，它不鼓励零碎的支付，如果交易的“输出”低于0.01BTC，那么就要收取0.0001BTC的手续费；优先支付历史久远和数量多的比特币；对交易数据“称重”，按每千字节收费。交易税作为一种从量税，在灵敏细致的数学算法调节下，可以实现较为理想化的征收，使得经常进行大量小额交易的特殊用户因不得不付出昂贵代价而有所收敛，又不至于让普通用户的交易较传统支付方式失去成本优势。即使有所偏差，也可以通过协议的升级不断微调。
A brief discussion on the mechanism design of Bitcoin
The fierce “arms race” of Bitcoin network has triggered concern over its fairness. At the beginning of its birth, every individual could mine the Bitcoin easily with a personal computer. According to Hal Finney, an early partner working with Satoshi, he gained thousands of Bitcoins within a few weeks which were mined by his personal computer. But nowadays Bitcoin has become the “private mine” of mega mining corporation and professional miners who own lots of ASIC devices, which seems to be unfair. People also worry that Bitcoins are concentrated in the hands of a small group of people, which hinders its promotion. The Coase theorem states, however, that with zero or little transaction cost and clear property rights, the market could reach its Pareto efficiency of resources allocation, no matter to whom the property is given at the very beginning. The whole system would also be fair if the ownership of the rights of property is set reasonably at the beginning. Satoshi did take a thorough consideration when designed the Bitcoin mining mechanism. He then was confronted with two options: one allocating Bitcoins to all users according to the number of the nodes, namely one-IP-address-one-vote; the other allocating Bitcoins to the miners according to the computing power, namely one-CPU-one-vote. He chose the latter considering the security of Bitcoin network. He wrote in the White Paper that “If the majority were based on one-IP-address-one-vote, it could be subverted by anyone able to allocate many IPs.” Miners obtain Bitcoins by processing transaction data, which could be considered as an incentive mechanism. In retrospect, however, miners should put in their computing power to obtain Bitcoins which could be deemed as a public resource. Since the security of Bitcoin network is proportionate to the network’s computing power, the computing power put in by miners are used to ensure the security of the network, enabling normal users to trade safely without putting in any computing power. This is fair to both the users and the miners. Although the initial allocation of Bitcoins is designed by the protocol, it is the market that decides the final allocation. Users possess the right to collect the computing power from miners and this right could be sold, which means miners “pay” the computing power to users in exchange for the ownership of Bitcoins in the block. On the other hand, miners possess the right to obtain the Bitcoins in a block and this right could also be sold, which means users could purchase Bitcoins from miners without putting computing power. If the computing power paid by miners is higher than the revenue generated by mining, miners would put in less computing power; correspondingly if the expense paid by users to purchase Bitcoin is higher than the mining cost, more and more users would join the mining industry. The market would reach equilibrium at the end and a highly-efficient allocation between computing power and Bitcoins would be realized. In the first days after Bitcoin was created, transaction cost is almost zero and some special users could realize certain goals with small-amount-transaction. For example, Wikileaks coded some secret files in the blockchain with huge quantities of small-amount-transactions; Gambling websites like SatoshiDice informed their users of the gambling results (or even sent commercials)with small-amount-transactions. These actions has put more burdens on the overstuffed blockchain. Apprently those users who overuse the small-amount-transactions have taken too much public resource and a transaction tax imposed to them is necessary and reasonable. This Pigouvian-Taxes-like design could reduce the junk transaction to a huge extent and equalize the private cost and social cost of the transaction. The rule of levying the transaction tax of Bitcoin is calculated to be economical. It discourages trivial payment, which means that if the output of a payment is less than 0.01BTC, a transaction fee of 0.0001BTC should be collected; A payment with bitcoins of longer history and more amount is prioritized; The trade data is “weighed” and a fee is collected for each kilobyte. As a unit tax, the transaction tax could be levied relatively ideally with the adjustment of deft mathematical algorithm, and consequently those special users who do lots of small-amount-transactions must refrain due to the expensive cost, while normal users could still keep the cost edge compared to traditional ways of payment. Even if there may be some inaccuracy, micro-adjustments could still be made by updating the protocol.