Mr. Koizumi, whose change of views is startling, shows that there is quite a split on the issue in the political class. As a pro-growth prime minister from 2001 to 2006, he was an enthusiastic proponent of cheap and clean nuclear power. Now he declares that it is the most expensive form of energy, citing not only the many billions of dollars needed to clean up Fukushima but also the unknown cost and method of dealing with nuclear waste.

He also criticizes the current government’s assumption that nuclear power is essential for economic growth. Ever the acute reader of political moods, Mr. Koizumi argues that a zero nuclear policy could be cause for a great social movement in a country still gripped by economic gloom after 15 years of deflation.

In the wake of Fukushima, one would think that the Japanese government could not restart nuclear power reactors without firm public support. Not so.

According to opinion polls, the majority of Japanese oppose nuclear power, even among supporters of the Abe government. A poll last week found that 76 percent of those surveyed said they did not think the Fukushima plant was “under control.” The government reckons the earthquake and tsunami that struck Fukushima is a once-in-a-thousand-year occurrence. Yet it also estimates that there is a 60 percent to 70 percent probability of a major earthquake and tsunami hitting the most densely populated coastline within the next 30 years. That coastline, dotted with nuclear power plants, reaches from Tokyo to the southern island of Kyushu.

Prime Minister Abe has been stressing the need to shed the deflation mentality for Japan to lift itself out of economic stagnation. Japan can certainly do with a change in attitude. Mr. Koizumi makes a compelling argument that if the ruling Liberal Democratic Party were to announce a zero nuclear policy,