Alarmed by what he called a preoccupation with government costs rather than quality of services, incoming Arlington County board chairman John W. Purdy this week urged the three-member liberal board majority to vote as a bloc to finance schools and social services in 1978.

Purdy's 10-minutes speech as newly elected chairman highlighted the board's traditional but relaxed New Year's Day organizational meeting held Monday. About 75 people attended the hour-long meeting, most of them members of the local Democratic party and the nonpartisan Arlingtonians for a Better Country.

Since 1970, the five-member board has been controlled by a majority coalition of members elected with endorsements from both groups. Purdy, outgoing board chairman Joseph S. Wholey and vice chairman Ellen M. Bozman represent that coaliton.

However, in the past two years, sharp divisions have arisen over Wholey's role as the swing vote in a "floating majority." A fiscal conservative, Wholey frequently votes with Repoublican-endorsed board members Dorothy T. Grotos an Walter L. Frankland Jr. and against Bozman and Purdy on budget matters.

Purdy's speech focused on precisely that topic. "There is a definite preoccupation with the costs of local government rather than the quality of service," said Purdy, glancing pointedly at Wholey. "In the recent past, we frequently have not acted as if we represented a common constituency.

"I do not believe that our first objective should be to reduce taxes of any kind, including real estate taxes."

Purdy's statement that schools should be more adequately funded was met with loud applause.

"We in the majority have pointed with some pride in our campaigns to the fact that the total tax burden . . . is the lowest in the metropolitan area . . . We are also one of the wealthiest communities," Purdy noted. "Allowing cost to govern policies and programs will not produce the attractive community that we have said we want. . . We in the majority must take the lead by acting like the majority."

Following Purdy's speech, Frankland noted, "The general taxpayer has paid his share and should not be called on to do more. I think there were four people clapping for higher taxes when you mentioned it in your speech."

In an interview after the meeting, Purdy declined to mention specific tax increases but noted that the real estate tax is the key to adequate funding. "This is a wealthy community," he said. "We have tended to listen too well to people who complain about taxes."

Wholey commented afterwards that "John's position is to raise taxes. He's said that since he's been on the board. That's a good, philosophically defensible position but it's not the position of the county board."

Wholey noted that the area of difference between his position and Purdy's is "very small, about 1 and 2 per cent in a budget of $140 million. There is general consensus about roughly what level of services and taxes we wish to have."