Decipher this

I always want to understand economics (and also be good at it!) solely because I thought it tries to theorise common sense, until I formally studied the Theory of Positive Economics in my MBA. Here is one of the statements from  Theory of Positive Economics, it goes like this:
 
"Assumptions of a hypothesis can be used to get some indirect evidence on the acceptability of hypothesis in so far as the assumptions can themselves be regarded as implications of the hypothesis."
 
I needn't say how much common sense this statement sounds. :-)
 
I will write more on my experiences with Economics.