French President Francois Hollande has been confronted by the glaring light of reality -- sort of.

On New Year's Day, as his massive tax increases began taking effect, Hollande, a member of the Socialist Party, admitted that taxes in France have become “too heavy, much too heavy.”

Indeed, as of Jan. 1, French households now must contend with a new value-added tax on many goods and services and, writes International Business Times, “French companies will be required to pay 50 percent tax on all employee salaries in excess of 1 million euros. … The effective tax rate will amount to 75 percent.” Unemployment, which Hollande promised to reduce, has risen to nearly 11 percent. Some companies and wealthy people have left France in search of business-friendly environments. More will surely follow unless Hollande's rhetoric is followed by actual tax reductions.

Hollande's head-on collision with reality is reminiscent of President Clinton's remarks in 1995 at a campaign fundraiser in Houston: “Probably there are people in this room still mad at me … because you think I raised your taxes too much. It might surprise you to know that I think I raised them too much, too.”

Neither Hollande (so far), nor Clinton, followed up on their remarks by cutting taxes. Like many other politicians, these men tried to have it both ways.

The next political leader who will be forced to adjust his left-wing ideology to reality is the new mayor of New York City, Bill de Blasio, who has proposed a tax on the wealthy to fund universal pre-K education. He, too, thinks raising taxes on the successful is the way to prosperity for the poor. He should pick up the phone and ask Hollande how that is working for him, as Hollande's approval ratings are sinking faster than President Obama's. Even better, he might recall Calvin Coolidge's remark: “Don't expect to build up the weak by pulling down the strong.”

Penalize success and prosperity and you get less of it. Subsidize bad decision-making by giving taxpayer money to the poor, and you may well undermine initiative and personal responsibility and create new generations of poor people.

The Left in America and France have gained political power by appealing to voters' emotions, but when they achieve power their ideology harms the very people who voted for them when these well-intentioned programs prove unworkable. This presents conservatives and Republicans with an opportunity, as well as risks.

Liberals are allowed to be as ideological as they wish, and the major media and too many among the unfocused public will mostly support them. The Left is never told they must compromise their ideology when reality proves them wrong, or “work with Republicans and conservatives” to achieve common goals. That is the trap liberals set for conservatives, who are repeatedly told they must compromise their principles if they hope to win elections, but whose squishy politics then become as unappealing as cold oatmeal.

Here is the path Republicans and conservatives must take if they not only want to win, but bring positive change to the country. Instead of debating feelings and ideology with the Left (territory on which they almost always lose — recall “compassionate conservative”), conservatives should hold their opponents accountable. Are their policies producing the results they claim? Is the record debt good for the country? Are agencies performing as their charter demands, and should their budgets be reduced or the agency eliminated if it can’t show results? Every government agency and program should be regularly required to justify, not only its budget, but its very existence.

Americans typically hate waste. It is why as children most of us were told to clean our plates because somewhere in the world there were hungry people. Requiring the Left to prove their programs and policies are producing outcomes at reasonable cost would shift the debate from ideology and good intentions to reality. This is where conservatives have a distinct advantage if they will embrace it.

CAL THOMAS, a Washington Examiner columnist, is nationally syndicated by the Tribune Content Agency.