'We are the fragment'

The West has its dissenters, holding their positions as tenaciously as the freshly publicized ''Siberian Seven'' group of Soviet Pentecostalists and ''Charter 77'' group of Czech civil rights advocates. Indeed, Western demonstrators were out protesting various government policies the same week a family of Soviet Pentecostalists was finally allowed to leave the Soviet Union; the same week Czech police broke up a meeting between Charter 77 members and Western pacifists visiting Prague for a peace conference.

Is simply reporting these events enough to dramatize the difference between disagreeing with governments in the West and in the East? It should be. And yet an anonymous ''citizen of Prague'' found the difference worth noting to Western delegates on the way to last week's government-sponsored World Assembly for Peace and Life Against Nuclear -ar. t cannot be noted too often, especially perhaps when communists lay on a peace celebration that tries to exploit the very Westerners whose kind of activism is denied to the local citizenry.

Here is where ''a citizen of Prague,'' writing in the Times of London, warned Western peace delegates in advance:

''Your movement makes life more difficult for your rulers, because you submit them to open criticism. But our rulers - who are subject to no criticism whatsoever - merely add your voices to their arsenal.

''If we were to attempt to express our opinions concerning the preconditions for peace - to take the most pertinent example, the absence of an occupying army from our national territory - our rulers would receive and entertain us also, but in prison.''

Whenever citizens of the Western democracies are tempted to give up on their causes, they might remember how much harder it is for the Czechs to call for something even as basic as freedom - as scores were arrested for doing during the peace conference. How much harder it was for the Soviet Pentecostalists to act on their beliefs, what with hunger strikes and with several of them sitting in at the US Embassy in Moscow for years. At this writing, while 15 members of one family were allowed to emigrate, two members of the original Siberian Seven were still not released.

Yet under every iron heel somebody keeps a gossamer hope alive. ''We are the fragment - whether remainder or germ - of public opinion in our country,'' writes ''a citizen of Prague.'' A state without unofficial public opinion ''is a danger to its citizens - and therefore a danger to peace.'' How important for those where public opinion flourishes to cherish their treasure and use it well.