"To define the paths" means to establish or determine the specific courses of action or direction to be taken in order to achieve a particular goal or outcome. Full definition
For 36 % of the men asked, the first date is essential for defining the path of a potential relationship. (elitesingles.co.uk)
So does its ability to guide one along surprisingly well defined paths. (haberarts.com)
They had clearly not yet defined a path, although there was some recognition that a generation's economic reality could not sustain itself. (mauldineconomics.com)