On Monday, President Donald Trump admitted that he had no idea the health care issue was so complex. On Tuesday, in his address to a joint session of Congress, he demonstrated that he had no idea how complex the federal budget was, either.

The most ill-prepared man to assume the White House in modern memory outlined a set of budget proposals that are completely contradictory. You can argue about any president's budget priorities, but America's financial physics are inarguable.

So even if you agree with Trump that boosting military spending by $54 billion is a good idea — and we don't — you still have to figure out how to get that $54 billion. Trump says he won't touch Social Security and Medicare, which together account for 38 percent of all federal spending.

Throw in other entitlements, including unemployment, Medicaid and health insurance subsidies, plus interest on the debt and veterans benefits, and you're at 71 percent of the budget. Add the 16 percent that the military already gets, you're at 87 percent, which leaves 13 cents on the dollar for everything else the government does — "non-defense discretionary" in budget-speak.

Trump has mentioned a couple of cuts that are red-meat favorites: cutting spending for the National Endowment for the Arts ($148 million, or 0.02 percent of federal spending) and "foreign aid" ($42 billion, or about 1 percent of the budget). But 40 percent of the foreign aid budget goes for "security assistance" (arms packages for allies like Israel, narcotics interdiction and bolstering allies in Afghanistan and Iraq). The remainder is spent on niceties like Food for Peace and global health initiatives, which military experts say are vital to U.S. national security.

So unless Trump is going to eliminate 75 percent of everything else the government does, his budget ideas are impossible - particularly as he also wants to cut taxes, build a $25 billion border wall and embark on a $1 trillion infrastructure program. No wonder his businesses declared bankruptcy six times.

Fortunately, the "skinny budget" that Trump will submit in mid-March is just the start of the budgetary process. A full budget package isn't due until May. Congress isn't likely to buy much, if any, of it.

Republicans are adamant that something must be done to hold down the ever-expanding growth in Social Security and Medicare spending. Without it, they can't have the tax cuts they crave.

Democrats and a lot of Republicans realize that clean air and water programs, food and drug safety, health and science research, and farm programs are not only good for the country but politically popular.

Trump is a fabulous salesman: "Everything that is broken in our country can be fixed. Every problem can be solved."

Sounds great — if you ignore the details.

REPRINTED FROM THE ST LOUIS POST DISPATCH