UPSET BY RISING taxes and angered by the inefficiency of state government, Bay State voters seem in a mood to approve Question 2 on next Tuesday's ballot, a tax-cutting referendum popularly known as Proposition 2 1/2. Should they succumb to that temptation, however, they would be virtually extinguishing local government in the Commonwealth, trusting only to faint hopes for tax reform to save Massachusetts from disaster.

"If Prop 2 1/2 passes, within three years Cambridge will have a volunteer fire department and a lot more parking lots," a city firefighter told community residents at a meeting last week. His conclusion rests on statistics compiled by city manager James L. Sullivan which show that within three years the city would have revenue enough only to pay the interest on its debt and other fixed costs. No police. No firemen. No schools.

Backers of Proposition 2 1/2--mostly state businessmen--call the claims of Sullivan and others "scare tactics." Their advertisements tell voters that disaster does not await the passage of the referendum; rather, they say, it will force the legislature to reform the state's tax system. While reform to decrease dependence on the antiquated property tax is needed, it is foolhardy to trust the legislature to provide that relief. The legislature, after all, originally enacted and has since maintained the property tax.

In a way, the supporters of Proposition 2 1/2 are right when they term the dire forecasts of municipal leaders "scare tactics." People who aren't scared that cities like Cambridge could be without schools, without services, without police protection should support Propostion 2 1/2. The rest of us, who would like to be able to call on the fire department when the flames break out, must vote in record numbers to insure the defeat of this unsound measure.