Romeo and Juliet Introduction (Book)

Scholars are divided on the role of fate in the play. No consensus exists on whether the characters are truly fated to die together no matter what, or whether the events take place by a series of unlucky chances. Arguments in favour of fate often refer to the description of the lovers as "star-crossed". This phrase seems to hint that the stars have predetermined the lovers' future. Another scholar of the fate persuasion, Draper, points out the parallels between the Elizabethan belief in humorism and the main characters of the play (for example, Tybalt as a choleric). Interpreting the text in the light of the Elizabethan science of humorism reduces the amount of plot attributed to chance by modern audiences. Still, other scholars see the play as a mere series of unlucky chances—many to such a degree that they do not see it as a tragedy at all, but an emotional melodrama. Nevo believes the high degree to which chance is stressed in the narrative makes Romeo and Juliet a "lesser tragedy" of happenstance, not of character. For example, Romeo's challenging Tybalt is not impulsive, it is, after Mercutio's death, the expected action to take. In this scene, Nevo reads Romeo as being aware of the dangers of flouting social norms, identity and commitments. He makes the choice to kill, not because of a tragic flaw, but because of circumstance.

http://en.wikibooks.org/wiki/William_Shakespeare%27s_Works/Tragedies/Romeo_and_Juliet#Fate_and_chance