The major theme of T. S. Eliot's "The Love Song of J. Alfred Prufrock" is indecision. Although the narrator claims not to be a Prince Hamlet, but merely an attendant lord, in fact he suffers from the indecisiveness that was Hamlet's hallmark. In the case of Profrock though, the background of the revisoons and indecisions is not heroic Denmark but the modern world of London society, marked by an self-consciousness spawned by the great intellectual revolutions of the Victorian era. In a world after Freud, Marx, and Darwin, our decisions are interpreted as always reflecting forces somewhat beyond our control, all acting upon us and pulling us in multiple different directions. Life was less complex before evolution (when we were ragged claws scuttling on a seabed) or in the medieval world where romantic activity was guided by the secure and unquestioned authority of the Roman Catholic church.
Prufrock can see all sides of the possibilities of both inaction and action from multiple perspectives -- making it harder rather than easier to make choices. In fact, this superfluity of knowledge makes any choice as good as any other -- thus :Do not ask what is it/ let us go and make our visit."