Big government, by big taxes, continues to expand social services. But it still leaves the multimillionaire many philanthropic choices of his own — endowment of pioneering research, for instance — as alternatives to the inheritance taxes. To find out why more Americans fail to exercise that choice. JOHN PEARSON sought the opinions of thirty wealthy men and tax attorneys. Mr. Pearson was among the small group of skilled administrators selected to launch the Federal Security programs. More recently he has been Managing Trustee of the Hanover Institute, Hanover, New Hampshire, seeking to finance the Institute’s basic research leading to a greater understanding of the nature of man and his problems.