I'm sorry, but organic farming cannot feed the world.

When pesticide and fertilizer and diesel fuel inputs become too expensive, it will have to do. World oil depletion will result in world population depletion.

Its hardly demonstrable that pesticide, fertilizer and diesel fuel will become too expensive.

It is a fact unless you can demonstrate that the rate of petroleum production will increase in the future.

The law of supply and demand is not a theory.

You misunderstand; All these inputs aren't solely dependant on petroleum. Pesticides and fertilizer can easily be manufactured with nuclear process heat and electricity, and diesel fuel can also at a high price.

Second, fuel demands for agriculture are relatively low while food demands are relatively high. There are plenty of surplus industries that will die first, from airlines to large commuter cars.