deisik:  I feel your pain, debating these Troglodytes.

That said I think the Quantity Theory of Money could be of assistance.  It is a simple and ancient formula that every economic school aknowleges.

The Formula is M * V = P * Q

M is Money Supply
V is Velocity, the number of times each money unit is transacted in the defined time period
P is the Price level of Goods and Services
Q is the Quantity of Goods and Services exchanged during the defined time period

Now once we have this formula we can clearly see that when any one factor is going up or down it must be balanced by a movement of one or more of the other factors (which factor tends to move more or less is a whole other area of debate).

If we assume that Q quantity is going to rise then their are 3 possible response, P decreases (deflation as prices are dropping), or an increase in V or M.  Now in BTC M is completely fixed (and in reality it will decline slowly from lost coins).  So this leaves only higher V and lower P as options.  Velocity in BTC could indeed rise a lot as most coins are hoarded but the overwhelming attitude is one of holding onto coins with a death-grip, and even if people did hoard their are probably practical limits to have high V can go.  This leaves a falling P as the only real option and hence the prediction of deflation (which has been spectacularly correct).  Really their can be no argument here both the pro and anti BTC sides of the debate expect deflation.