Sufficient reason and reason enough

I offer an analysis of the Principle of Sufficient Reason and its rel- evancy for the scientific endeavour. I submit that the world is not, and cannot be, rational -- only some brained beings are. The Principle of Sufficient Reason is not a necessary truth nor a physical law. It is just a guiding metanomolog- ical hypothesis justified a posteriori by its success in helping us to unveil the mechanisms that operate in Nature