OPPOSITION politics has reached a low ebb in Singapore, with leaders of the main minority party engaged in a public row and young Singaporeans apparently frightened to play a nonconformist political role. At a recent National Youth Seminar, participants were sceptical about a government call for more active youth involvement in politics, pointing to a ban on civil servants, unionists and student groups taking part in political activities and the harsh response suffered by anyone who spoke out against the Government. A student said the call was aimed at getting people to join the ruling People's Action Party (PAP), not opposition parties. In an address to the seminar, a Straits Times journalist, Cherian George, said the Government needed to grapple with the fact that one reason Singaporeans did not want to get involved in public affairs was fear. He said the Government had a reputation for a ''kind of intellectual intolerance and thuggery''. ''In Singapore today, critics risk having their arguments over-simplified, being labelled as belonging to some dangerous intellectual tradition, having their motives questioned and their qualifications ridiculed publicly,'' he said. Following the seminar, a Singaporean said in a letter to the Straits Times that there was a persistent perception of the PAP as being both self-righteous and high-handed, with a penchant for insisting that it was always right. Another letter writer said many people, whether young or old, dared not speak up in public for fear of being ''marked'' by the authorities. For those disinclined to enter politics due to what have been called the PAP's ''karate tactics'' against opponents, the in-fighting in the opposition Singapore Democratic Party (SDP) would have provided further discouragement. Following a speech in which Chiam See Tong, the former secretary-general of the SDP publicly criticised the present party leadership, a member of the central executive committee told this correspondent that some people wanted to see him ''given the boot''. The official said Mr Chiam's remarks, which were seen as a ''stab in the back'' of the acting secretary-general, Dr Chee Soon Juan, had angered many people who had ''long been close to him'' and widened the divide between himself and the committee. Despite the problems of the SDP and public fear of facing up to the PAP, some analysts believe opposition parties will continue to receive a strong protest vote. ''People vote for the opposition not because they want alternative government but to register their dissatisfaction with government policy,'' said Walter Woon, an associate professor of law and a Nominated Member of Parliament. He said if prices went up next year, there would probably be an increased opposition vote, ''notwithstanding the disarray in the SDP''.