French President Hollande’s Great Leadership Reversal by Geoff Colvin @FortuneMagazine November 30, 2015, 1:27 PM EST E-mail Tweet Facebook Linkedin Share icons When a leader reverses positions diametrically, is he or she responding wisely to new circumstances, or weakly abandoning principles under pressure, or cynically triangulating among political forces? Those eternal questions are embodied in one man this week, French President Francois Hollande. He’s in the news for multiple reasons, hosting the U.N. COP21 climate change conference in Paris, managing France’s response to the terrorist attacks, intervening in the Middle East, and facing regional elections in six days. Hollande’s transformation has been so dramatic that it will be studied by scholars and political analysts for years. He’s a small, bespectacled Socialist who spent his career demonizing corporations and the rich, aggrandizing the state as the solution to society’s problems, and shying from confrontation. As he campaigned for the presidency in 2012, Britain’s Guardian newspaper noted that he “so hates fights that he was once nicknamed ‘the marshmallow’ within his own party.” Now he aspires to be the opposite of the marshmallow, declaring war on “jihadi terrorism,” bombing ISIS positions in Syria, and promising to eradicate it around the world. He has declared a state of emergency that gives him extraordinary powers. He has promised to revoke the citizenship of convicted terrorists who hold two passports and to expand France’s security forces. All these initiatives are antithetical to longstanding Socialist doctrine. Hollande has reversed himself even more dramatically on economic policy. Immediately after taking office he famously instituted a 75% top tax rate on personal incomes over €1 million a year. The tax yielded minuscule revenue compared with the country’s huge budget deficit, and it hobbled French companies trying to attract top-performing executives and French soccer teams bidding for players. When the tax expired after two years, Hollande made no attempt to renew it. More significantly, broader business tax increases that he had instituted in his early days as president were slowing the economy, which was barely growing at all. So Hollande transformed himself into a tax-cutting supply-sider who is shrinking government’s role in the economy. He is pushing through a €41-billion package of tax reductions and other benefits for business. This is decidedly novel policy for a Socialist. In reversing so many positions, is Hollande reacting prudently to hard realities or just fighting to save his own political life? He is France’s least popular leader in modern times, and the political right has seized on the terrorist attacks as an issue; even after the Charlie Hebdo massacre in January, they say, Hollande did not respond sufficiently to keep us safe. The country’s regional elections begin on Sunday, and a shift to the right is virtually certain. Successful leaders almost always change their positions, and their motivations are rarely simple or pure. That’s only one reason Hollande is especially worth watching just now. Suddenly at the center of global debates on terrorism, Middle East policy, climate change, and economic policy, he has become the world’s most instructive case study on leadership. Sign up for Power Sheet, Fortune’s daily morning newsletter on leaders and leadership.