CHICAGO -- The campaign for the governorship of Lincoln's state is proceeding in the modern manner, each candidate explaining that the other fellow is a marble-hearted fiend and a fiscal dipsomaniac. The interesting wrinkle is that, at first glance anyway, the Democrat seems to be running to the right of the Republican.

First glances can be deceiving, but first glances are the most that many voters give candidates. That may be what the Democrat, Neil Hartigan, Illinois attorney general, is counting on.

The Republican, Jim Edgar, Illinois secretary of state, may be counting on the truth of an axiom expressed by a Democratic president. Harry Truman, disgusted by tepid Democratic candidates, said: "Give people a choice between a Republican and a Republican, and they will pick the Republican every time."

The heart of the matter, indeed the only thing that seems to matter, is taxes. In June 1989, a temporary (two-year) state income-tax surcharge of 20 percent went into effect, with half the revenues for education. Hartigan promises to let it expire next June without any cuts in education. Edgar favors keeping it and talks instead of property-tax relief.

Hartigan, a red-haired product of the Irish portion of this city's ethnic stew, sounds like another man of Irish descent, a down-stater from Dixon. Like Ronald Reagan, Hartigan promises to cut taxes and balance lost revenues by cutting government.

Skeptics are thick on the ground, thanks to (among other things) $2 trillion of debt Reagan piled up. But Hartigan, sounding like Herbert Hoover, promises businesslike government based on his business principles. It will, he says, be a snap to cut the budget 2 percent ($573 million from $26 billion), trim 2,500 from the payroll of 86,000 and cut administrative costs 10 percent.

The achievement is, perhaps, conceivable. The idea is certainly political. Hartigan says, with commendable bluntness, that he is "not letting the Republicans define me." Define him, that is, on the wrong side of today's taxaphobia.

Edgar is betting that voters will not believe Hartigan's promises. Edgar is counting on doubts about Hartigan's "character," doubts nourished by skepticism about his promises. Edgar thinks voters have been made skeptical by (he does not stress this) Ronald Reagan, George Bush and incumbent Republican Gov. Jim Thompson.

Thompson has been governor for 14 years. Twice he ran vowing not to raise taxes, then raised them. But Hartigan is overreaching when he says Thompson raised taxes 29 times. (To take just one example, Hartigan counts as four tax increases an increase in the annual vehicle-licensing fee, which covers four categories of vehicles.) The truth reveals how hard it is to make sense of today's politics of taxaphobia.

Thompson presided over many tax increases, but also has reduced or eliminated 20 taxes. Before the 1989 surcharge, the growth of state revenues was below the inflation rate. Real revenue each year did not exceed what it was when Thompson took office in 1977. Furthermore, state revenue has grown slower than personal income in Illinois. State taxes take about $57.40 of every $1,000 of income, which is $9.50 less than in 1978.

However, what counts is what voters feel, and there is no accounting for that. Hartigan has done well with an ad depicting Illinois pounded flat by the word "taxes."

Both candidates are better, more interesting men than their taxation-fixation makes them appear. Hartigan, 51, with his coat and his caution off, has honest passions about Illinois ranking 44th among the states in infant mortality and about the mothers of his childhood neighborhood now living "in two-room flats with a hot plate for company." Watch it, Hartigan, you are sounding like a Democrat.

Edgar, 44, is trying to become the first down-stater elected governor in 60 years. (This year, all six Democratic candidates for state offices are from Cook County.) He is admirably determined to walk on the risky side of the surcharge issue rather than risk winning in a way that might later add to the tide of cynicism.

Both candidates are stressing (as is the Democratic nominee for governor of Massachusetts, John Silber) what deserves to be the principal domestic issue of the 1990s: early intervention in the lives of poor children. The public's concern about all sorts of education is almost as strong as its taxaphobia. Almost.

No Democrat has won the governorship since 1972. With Illinois listed among the 16 states already in recession, this might be the Democrat's year. But the Democrat who won in 1972, Dan Walker, later went to jail.

Both candidates are moving gingerly among voters whose attitude toward politicians is: Go directly to jail; do not collect taxes.