When it comes to politics. Boston's are like no other. Urban problems--corruption, racism, crime, education, housing--are placed under a magnifying glass and appear in all their ugly splendor every four years.

Mayor Kevin H. White, in office for 16 years, is under fire, accused of running a corrupt political machine which is incapable of dealing with the city's problems. The Hub press, once firmly in his corner, now vigorously works to uncover new failings and improprieties in the White administration.

The school system is in shamble, observers say, still reeling from the racial tensions stirred up by court-ordered busing seven years ago and a resulting drop in enrollment of more than one-third.

White's handling of the tax-revenue cuts of proposition 2 1/2 has been questioned. Many police and firefighters were laid off and several firehouses and police stations were shut down, an action some observers say allowed the city to avoid confronting municipal waste.

Recent polls show that more than 70 percent of the city is displeased with White's performance, indicating the possible repercussions of the White administration's policy-making.

But White will almost surely seek reelection this November and no one. not even his competitors, is willing to count him out.

Currently, six challengers have said they will compete for White's job:

* Lawrence S. DiCara '71. A young but experienced politician, a city councilor from 1971 to 1981, the lifelong Dorchester resident says he will garner support from all parts of the city and will work to reconcile business and neighborhood interests.

* David I. Finnegan. A former Boston School Committee president and a fourth place finisher in the 1979 mayoral race. Finnegan is the latest entrant in the race. The WBZ radio talk-show host could present a challenge to White, but he is still about $70,000 in debt from his last campaign and may not be able to organize and raise money before the September primary.

* Raymond L. Flynn. Many observers think Flynn is the only man who can beat White. The South Boston resident and city councilor will probably draw most of his support from low and middle-income group. His only drawbacks may be his personality--he speaks slowly and in a monotone--and what some see as an inability to work with downtown Boston business interests.

* Robert R. Kiley. The only candidate who is not a Boston native, Kiley is also the only contender to have had significant experience in administration. He was White's deputy mayor from 1972 to 1975 and helped implement court-ordered busing in 1974. He managed the MTA for four years under Governor Michael S., Dukakis's first administration, but was fired when Edward J. King replaced Dukakis in 1979. The fact that the 46 year-old Minneapolis native has only lived in Boston for 10 years may hurt his September showing, especially in low-income and ethnic neighborhoods, still strongly motivated by back-slapping, old-style politics.

* Dennis J. Kearney '72. The youngest candidate at 33 years of age, the Suffolk County sheriff combines excellent fundraising and organizational skills with a flamboyant campaigning style--his vice-grip handshake is now legendary. Kearney began his political career as a service coordinator at White's East Boston Little City Hall and served as a state representative for East Boston and Charlestown between 1974 and 1977 before his appointment to his present post.

* Melvin H. King. The only minority candidate in the field may prove to be a serious contender if he can gain support from white liberal voters. A five-term state representative from the South End. King finished third in the 1979 mayoral election, behind Joseph F. Timilty and ahead of Finnegan. Timilty is not running, so King may well gain one of the top two spots in the September primary and a shot at victory in a two-man November runoff.

The complexion of the race, regardless of the number of challengers, will be determined by White himself. though he has gone as far as to call himself a "participant." he has not yet declared and possibly will not do so until shortly before the mid-June filing date.

The Money