For an example - studying the brain directly brings us to the fact that the pre-frontal cortex is responsible for personality and behavior. Philosophy could have never in a million years have discovered this. How can it then answer other questions that clearly deal with philological aspects of the brain?
It is not possible to freely will. This would suggest that we choose to have [un-willing] impulses. It would presuppose we could create every thought we have- and it posits that we could choose to not think at all. It is clear we make choices and we will things, but we cannot will to will- we are not free or aware of how the forces that brings us to will occur.
Merely speculating will not answer this question. You have to ask yourself: Am I free to think when I please?
If not then you are a slave to your thoughts. And it goes without saying slavery is the opposite of freedom.