Philosophy is essential. to provide what Bernard Lonergan called a 'common ground' of the operations through which we pursue meaning and truth, and to provide what is probably a solution to the fragmentation of knowledge by acknowledging the same operations of experiencing, understanding, and judging in all fields. This brings a startling unity to knowledge and to the pursuit of understanding in every field. It helps us relate such 'hard sciences' as mathematics, physics, and chemistry to the sciences of life, and to relate all of these to psychology, philosophy, the arts, and theology. 
The key is the act of insight. “...to grasp it in its conditions, its working, and its results is to confer a basic yet startling unity on the whole field of human inquiry and human opinion."