My father was the governor of Punjab, Pakistan's largest province, and his tweet, with its taunt at India's misfortune, would have delighted his many thousands of followers. It fed straight into Pakistan's unhealthy obsession with India, the country from which it was carved in 1947.

Though my father's attitude went down well in Pakistan, it had caused considerable tension between us. I am half-Indian, raised in Delhi by my Indian mother: India is a country that I consider my own. When my father was killed by one of his own bodyguards for defending a Christian woman accused of blasphemy, we had not spoken for three years.

To understand the Pakistani obsession with India, to get a sense of its special edge—its hysteria—it is necessary to understand the rejection of India, its culture and past, that lies at the heart of the idea of Pakistan. This is not merely an academic question. Pakistan's animus toward India is the cause of both its unwillingness to fight Islamic extremism and its active complicity in undermining the aims of its ostensible ally, the United States.

The idea of Pakistan was first seriously formulated by neither a cleric nor a politician but by a poet. In 1930, Muhammad Iqbal, addressing the All-India Muslim league, made the case for a state in which India's Muslims would realize their "political and ethical essence." Though he was always vague about what the new state would be, he was quite clear about what it would not be: the old pluralistic society of India, with its composite culture.