“Sometimes,” said Adel Abdel Maqsoud Afifi, a police general, lawmaker and ultraconservative Islamist, “a girl contributes 100 percent to her own raping when she puts herself in these conditions.”

The increase in sexual assaults over the last two years has set off a new battle over who is to blame, and the debate has become a stark and painful illustration of the convulsions racking Egypt as it tries to reinvent itself.

Under President Hosni Mubarak, the omnipresent police kept sexual assault out of the public squares and the public eye. But since Mr. Mubarak’s exit in 2011, the withdrawal of the security forces has allowed sexual assault to explode into the open, terrorizing Egyptian women.

Women, though, have also taken advantage of another aspect of the breakdown in authority — by speaking out through the newly aggressive news media, defying social taboos to demand attention for a problem the old government often denied. At the same time, some Islamist elected officials have used their new positions to vent some of the most patriarchal impulses in Egypt’s traditional culture and a deep hostility to women’s participation in politics.