With its total absence of any mention of patriotic sacrifice or of any appeal to unselfish national purpose, President Reagan's televised address in support of bigger increases in the defense budget lacked believability. It was a speech, like the policy it so faithfully reflected, conceived in contradiction and doomed to public disbelief. And in the same week he was giving it, some of the people who might be expected to challenge him on this and other matters--the Senate Democrats--were busy undermining their own believability.

In his approach to the American people on matters of national security, Reagan has been congenitally, if uncharacteristically, timid. From the very outset, his proposed price tag of $1.5 trillion for beefing up the nation's defenses was to involve minimal inconvenience. It was to be financed by an enormous tax cut, and, if that was not enough, by bigger budget deficits.

What Reagan apparently does not grasp is that Americans have a long and admirable record of making great sacrifices in behalf of their nation as long as those sacrifices are justly apportioned and serve a believable and understandable national purpose. Reagan has underestimated the patriotism and the unselfishness of the American people. Not yet, in publicly discussing the national survival during his presidency, has he asked the American people to sacrifice. Not yet has he demanded the best in us, the way presidents Roosevelt and Kennedy did so forcefully in times of national peril. When FDR sought Lend-Lease to save England, he stated: "Sacrifice means the payment of more money in taxes." He saw Americans "putting patriotism ahead of pocketbooks." And he was right.

The 1980 national consensus that clearly favored spending much more on national defense has crumbled. When given the choice between spending on an MX system that even Western GOP Senate hawks turned down for their home states or providing food and fuel for suffering American families, Americans preferred to attack cold and hunger first.

Senate Democrats, those self-styled tribunes of the underdog, had an especially undistinguished week as well. Traditional Democratic rhetoric about tax reform collided with the reality of the bankers' lobby and that group's all-out opposition to withholding on interest income. Overcoming all their moral outrage about tax avoidance and such, Senate Democrats managed to vote 35-10 with the bankers for repeal of the law that would simply treat those who receive interest income the way American blue-collar workers have always been treated. Senate Democrats have little standing now from which to criticize the president's failure to appeal to citizens' selflessness.