While I'm not completely sure what you are trying to say, let me take a few stabs at it:  

> The harder it is to define a notion, the greater chance it came from a woman.  

Try also:

> The harder it is to understand an idea, the more likely it is that it came from a woman. 



That implies women come up with ideas that are hard to understand.  Or if you're trying to say that, the harder it is to explain something the more likely that you're talking to a woman, then try

> The harder it is to explain something to someone, then the more likely it is that you're explaining it to a woman.