"In economics we have a concept called rational expectations where agents use all the available information to decide their actions in equilibrium. In this framework the halving in the block rewards would have been anticipated and factored into the price. You are right to emphasize that when doing a demand and supply analysis, it is not the coins produced on a daily basis that matter but rather the entire stock of bitcoins in circulation. In that way the price of bitcoin should not double for a halve in the hashrate, in fact the effect should be negligible. This is considering just transactional demand and total supply. With goods/commodities this is likely to hold true but in currencies or cryptocurrencies this may be different. There are issues of security and speculation.
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In my mind, economics would predict the hashrate to halve as the reward halves. Essentially the argument would go if the price has not doubled the hashrate must fall."