In Geneva this week, an Iranian delegation has been holding talks with six other nations about its country’s nuclear program. These negotiations — the first to take place under the auspices of Iran’s new president, Hassan Rouhani — inspired little bursts of positive rhetoric. The BBC reported an “upbeat mood” in Geneva. A European diplomat spoke of “cautious optimism.” Rouhani himself had pledged to “resolve” the nuclear problem within the next six months.