Be careful about your economic assumptions as we enter the Age of President Donald Trump.

MFS executives challenged assumptions that the new president’s spending and tax policies will bring jobs and capital back from abroad, the stock market will roar ahead and central banks in Europe and Japan will succeed in lifting bond yields.

At a luncheon Tuesday in Manhattan, they also said they were doubtful that the new president’s proposed tax cut and tariff changes will be “a game changer” that will boost the stock market.

“I will dispute that today. The election of a new party has never really had a dramatic effect on the markets,” said James Swanson, MFS chief investment strategist. He listed proposed Trump policies that would not help the market, including tariff increases he believes would redound to the detriment of the stock market and the economy.

He also warned that Trump’s proposed tariffs against China and other countries will hurt the American economy as other nations would retaliate. He argued that many S&P companies, dependent on foreign sales, would pay the price for protectionists policies.

But a president proposing something that has an unexpected result isn’t new. Swanson contended that presidential economic policies often have the opposite effect of what was intended.

For instance, President Reagan, despite promises to reduce government, ended with the government spending a bigger percentage of GDP than when his administration began. President Clinton, despite promises to expand the government’s social programs, actually reduced the government’s share of GDP, Swanson noted. Some expected the economy to tank under President Obama, yet the economy and the markets have done well, Swanson said.

He said GDP growth over the last seven years has been 2.1 percent. “That’s lower than normal, but that’s been OK. President Obama’s policies “didn’t hurt the economy,” Swanson said. It has been buoyed over the last eight years by strong corporate balance sheets, he added.

“But now,” Swanson cautioned, “many of those corporate fundamentals are weakening.”

Swanson questioned whether individual tax cuts advocated by President Trump would help the economy, arguing that the people who would receive the bulk of them would save the cuts and not spend or invest them. The policies of those overseas have had mixed results over the last eight years, another MFS official noted.

The European central bank has had mixed results raising yields and promoting inflation and more jobs. Although the unemployment rate was declining, “We should be troubled that it seems to be moving sideways now,” said MFS chief economist Erik Weisman. The Bank of Japan, he adds, has not been effective in promoting higher price and bond yields. “So far the market is not impressed,” he added.

Weisman said the enthusiasm that many feel for European and Japan central bank policies may be misleading some people. He said it is still possible for these policies to lead to even lower bond yields. “Just be careful about what we think we know when it comes to bond yields,” he warned.

On assumptions that Trump administration policies will inevitably lead to higher interest rates, Weisman said “we’ll see.” He also said that unless Donald Trump can eliminate the considerable structural economic problems that he inherits, his fiscal policies will not “be a panacea.” And Weisman cautioned that, despite all Trumps proposals, interest rates could “still go lower.”