PRESIDENT REAGAN has frequently used his high office to demonstrate concern for some person whose unfortunate circumstances have come to his attention. In his radio talk last Saturday, for example, he appealed for a liver donation for an 11- month-old girl whose life depends on a transplant operation. The appeal brought hundreds of calls--though not, as yet, a suitable donation--and it served the additional purpose of encouraging people to carry donor cards indicating that their organs can be used for transplants if they should die suddenly.

The desire to intervene in an individual hardship case--especially one as poignant as that of a small child facing death--is an impulse that most people can readily respond to and applaud. But the president's fondness for personal intervention points to a curious disconnection between his personal view of himself and his more general view of the responsibilities of the government he leads.

The point is that there are practical limits to the ability of any one person, even a president, to dispense enough favors to make a small dent in the mass of troubles afflicting the citizens of this country. And dealing on a case-by-case basis raises questions of fairness to all the other troubled people whose problems don't happen to catch the president's eye. Organized societies and the institutions they create are there precisely to deal with human troubles on a scale and on a basis that individuals cannot possibly manage on their own.

It would be nice to imagine that this assistance could depend solely on voluntary acts of generosity for their maintenance. But it has never been so in any large society. There are many skilled and caring people who have devoted their lives to charitable works and others who have found satisfaction in contributing to the support of such people. But the simple fact is that until government got involved in the business of social service, most of this nation's more unfortunate and afflicted people lived lives of misery--as such people still do throughout the world.

Removing the personal element from charity by having government or other large institutions take over tends, however, to reduce public support for these functions. Like the president, most people are ready enough to do a kind act when the situation forcefully presents itself. But no one takes personal satisfaction from paying his taxes. That's where presidential leadership could be really helpful--in reminding people that their taxes make possible not one or two, but literally millions of acts of day-to- day kindness of the most essential sort.