As Moby Dick comes to represent the forces of Nature (or god), the battle between Ahab and Moby Dick is a battle between Man and Nature (or Man and God).
Specifically, Ahab rebels against the notion that his fate might be determined by any power outside of himself. He insists, in the novel, on being the sole arbiter of his fate.
These conflicts are, of course, symbolic and for this reason require interpretation. However, in the case of this novel, the symbolism is rather clear. Moby Dick is directly aligned with nature and its abstract counterpart, Nature.
In developing the theme of the individual (Ahab) versus Nature (symbolized by Moby-Dick), Melville explores the attributes of natural forces.
In the book Moby Dick Ahab and Moby's battle is more Ahab's battle against himself. Ahab sees himself as a god like creature. When he comes up against Moby Dick he becomes thwarted by the whale's ability to resist him. Ahab must prove to himself that he is the greater who can conquer wall.
Ahab demonstrates little concern for others while on his quest. He is obsessed and dangerous. He aligns himself with the devil and he delves further into his conquest against the whale.
Ahab is connected to Moby Dick through an almost psychic ability to sense his presence. This connection further demonstrates the fight against his own self-identity that Ahab undertakes.
i think that the battle between Ahab and moby dick has philosophical side.it represents the conflict between man and nature,from the begining of creation,man has been in a struggle of power against all the natural powers.ahab,as ahuman being and as an obsessed man,didn't submit to the fact that he is weaker than the whale(who represent nature),so he decided to kill the whale if it cost him his own life.