Society does determine what is right through both logic and social constructs. The bigger question is what should we use?
The problem with social norms is that they encourage and rely on biases. Although this can be useful to make faster decisions and set a standard for society it is important to remember that bias can be used to dictate right from wrong without reasoning. This is what religion does and it's why we have multiple loonies telling us that God is punishing all of us for letting the homos run rampant.
What is the difference between a bias ... we all have them ... and an ideology ..... are the righteous loonies not engaging their ideology rather than personal bias ?? .... Does brainwashing distort the data ....