Charles A. Mosher, 78, an Ohio Republican who served in the House of Representatives and used his 16 years there not only to serve his district but to hone a keen sense of the paradoxes of government and life in general, died of congestive heart failure Nov. 16 at Allen Memorial Hospital in Oberlin, Ohio.

"A lot of my constituents have been unhappy with me over the years because of my yes-and-no answers," he said in an interview shortly before he retired in January 1977. "I find it impossible to give yes-and-no assurances. It's the nature of man to hunger for assurances, but I don't see things in black or white."

However wary he may have been of simple answers, Mr. Mosher was willing to go wherever his understanding of the facts led him. Thus in 1967 he became the first Republican member of the House to cast a roll-call vote against appropriations for the war in Vietnam. He said he profoundly regretted having voted for the Tonkin Gulf resolution in 1964 that authorized the major U.S. escalation in the war.

"I kick myself for voting for the Tonkin Bay resolution," he said in the interview. "I wish I was as smart and full of insight and courage as several other members of Congress were. I was fooled. I really bitterly feel betrayed on that vote."

Mr. Mosher was well known to the people of northern Ohio whom he represented, and if some of them were put off by his refusal to give yes-or-no assurances they nonetheless returned him every two years by substantial margins. He also was known to his colleagues on Capitol Hill, who regarded him as one of the most thoughtful of their number. But he was not widely known elsewhere, either in Washington or in the country.

He was a member of the Merchant Marine and Fisheries Committee and in behalf of his district he supported federal aid for Lake Erie ports and shipbuilding in the region. He also built up an impressive record of service to his constitutents on smaller issues that may have affected them as individuals.

But his outlook was wide ranging. He was the ranking Republican on the Science and Technology Committee and this allowed him to pursue one of his principal interests: the explosion of knowledge and its effect on the policy-making process. Congress has more information at its disposal than ever before, he used to say, and yet it is the paradoxical truth of the matter that it is less and less able to make decisions.

"Perhaps we are confused by the facts," Mr. Mosher said in his farewell interview. "Perhaps we are so much more aware of the complexities of the world that it makes us indecisive -- much more so than we were a few years back when we flew by the seat of the pants."

Mr. Mosher described the increased flow of information and the difficulty in absorbing it as "our Achilles' heel that makes us terribly vulnerable." This is so, he said, because the amount of data available is so great that people are inclined to look for simple answers rather than face the real complexities of life.

Having retired from his seat in the House, Mr. Mosher became staff director of the Science and Technology Committee. In 1979, he was named public programs director of the American Association for the Advancement of Science. He spent the next year at the Woodrow Wilson Center of the Smithsonian Institution.

In 1982, Mr. Mosher returned to Oberlin and the college that bears its name. There he earned a master's degree in government, becoming the oldest person in the history of the school to earn a degree. His thesis recommended four-year terms for members of the House and eight-year terms for senators. He said this would allow legislators to spend more time worrying about policy and less time worrying about reelection.

Mr. Mosher was born in Sandwich, Ill. He graduated from Oberlin and then began a career as a newspaperman. He worked on papers in Illinois and Wisconsin and then settled in Oberlin, where he owned a printing company and was editor and publisher of the college alumni magazine. He served on the City Council and in the Ohio legislature before being elected to Congress in 1960.

Survivors include his wife, Harriet, of Oberlin; two children, Frederick Mosher of New York City and Jane Frederickson of Bloomfield, Colo.; two brothers, Edward Mosher of Sun City, Ariz., and Dr. Henry A. Mosher of Boston, and six grandchildren.