Yes, the world has changed since 9/11 (or so Americans argue); the change demands a chronicler with a finger on its pulse. But why choose the lens of a day through which to focus one's vision of a changed world? Why make playing squash, visiting a demented mother, and shopping for seafood bear the weight of the world?
I think McEwan does not so much want to add to this genre as to quarrel with his predecessors. In adopting a single limited point of view, instead of a stream-of-consciousness; in describing an essentially sane and happy family, instead of madness, sickness and promiscuity; in deploying the language of science, instead of myth and magic, McEwan sets his brand of fictional realism against modernist fiction and its postmodernist progeny. And I sense, as I did when I read Atonement, that, despite side-swipes against Gunter Grass and Salman Rushdie, his chief antagonist is Woolf, the novelist of the same city McEwan would like to conquer.
The invocation of English enlightenment figures such as Hooker and Boyle on the one hand, and of archetypically English poets such as Matthew Arnold and Philip Larkin on the other gives a narrow nationalist edge to the argument. Terrorism is always Other, whether it be Saddam Hussein who needs to be taken out (Perowne is pro-war), the Russian pilots who are suspected of setting their plane on fire, or Baxter, the gangster who forces his way into the end of the day. Perowne, however, represents the English virtues of discipline, reason, clarity, professionalism and family loyalty; it's no accident, surely, that his first name is Henry. These English virtues are associated in the novel with fictional realism.
It would be wrong to equate Perowne with his creator. It would also be wrong to overlook Perowne's capacity for self-criticism and reflection. But the identification of neurosurgeon and novelist, especially in the passages describing the former's surgical work, is peculiarly strong. And though Perowne wonders about his philistinism regarding poetry, his marital contentment (Does he lack virility?), and his pro-war stance, the mild questioning does not lead to any change in him. How can it? How can a disposition, cultivated over a lifetime, and inherited from the past the way one inherits a house or one's genes, change in a day?