What actually happens despite how I think things work is reality. If I'm bad at judging the consequences of my actions then my view of reality is poor. Just because all knowledge is seen through lenses doesn't mean all lenses are equal. A person who can predict the consequences of actions accurately is seeing the world through clear lenses.

There was a time when no one knew the equations of gravity in exquisitely rigorous detail, yet if you walked off a cliff, you would fall. http://www.yudkowsky.net/rational/the-simple-truth/

It's funny that in a discussion about sexism, you are hanging your hat on the objectivity of physics.

Here's a quick reminder about why sexism is bad. Sexism is bad because it disadvantages people through no fault of their own. Sexism is part of reality. Theories and opinions about sexism do not effect the actual impact of sexism. You could be looking through a lens where you can't see inequality, but that doesn't mean there is none.