I think btc price will definitely rise after december and demand might just push it above 20 in february or so, It helps when your wife is an economist
Why should that be the case? It might happen, but there are reasons to think the price won't go up after the reward halving.
miners have little impact on the market right now, they will have half that impact after the reward halving. that is all
Supply of fresh btc to the market will be lowered, miners, who pay electricity will try to compensate their lowered income by raising the price, speculators and outsiders will think this price bump is the sign they were waiting to buy before another 30$ peak so people will buy and hold to their btc as everybody who has btc will be hoping btc will rise more. Expectations may cause short term jumps, total market is shallow (30-40 million ?) .
but of course it's impossible to predict future, mtgox might get stomped upon by some government or banks in the meantime so trust in bitcoin might go down with the price, or someone might decide to attack Iran and gold, oil will jump and everyone may forget about bitcoin for a while, aliens might invade earth and vaporize our rigs , some huge vendor might start to accept bitcoin, then it will go up. If nothing weird happens it will go up I think
I just posted about this in another thread, but I'll post it here too. The problem is if the price doesn't immediately and sufficiently go up after the block reward halving. If it does not, then less efficient miners' profits will be immediately cut in half, making many of them unprofitable. This will probably compel lots of miners in that category to finally drop out. This will leave only the more efficient miners - e.g. FPGA miners - as they can tolerate such a production increase as their operating costs are much less. The remaining efficient miners toleration of reduced profits could lead to competition for those profits, effectively decreasing the price.
I think there's a good chance the price does not immediately and sufficiently go up after the block reward halving because I think there's a good chance people will attempt to price a potential price increase in ahead of time, and if enough people with enough market influence price it in ahead of time, it won't happen at the time.