What if I want to do a PhD. Well you will realize that you don't know enough Math to do a PhD in Economics. Go study something more interesting.
A: Fine, I buy them off that illegal immigrant for £1.50
Hence the laws of Supply and Demand are and the concept of economics is satisfied.
Economist: Well if one looks at it from a non-inflationary enviorment, disregarding the laffer curve, then my hypothesis was in fact correct. Its Economics 101
Economics isn't meant to explain everything, but it is good for establishing parameters, distinguishing relationships, identifying issues, clarifying options and providing an analytical framework.