He was a prominent activist and thinker in the Charter 77 movement - a group whose wide spectrum of opinions was often obscured by the solidarity of anti-Communism - and his central Prague flat became a centre of alternative intellectual life during the grey years of the 1970s and 1980s.
As the clubby, tight-knit dissident world broke up after 1989, Benda helped found the right-wing Christian Democratic Party (of which he was chairman for four years), turning his back on many of his fellow dissidents who joined more left-leaning parties. He was elected to the newly democratic Czechoslovak Federal Assembly in June 1990, remaining in the Czech parliament after the country split in two in January 1993.
He was elected to the upper chamber of parliament, the Senate, in November 1996. That same year the Christian Democratic Party merged with the Civic Democratic Party of Vclav Klaus.
Benda's political activity began in the heady days of the Prague Spring in 1968 when he was a student in the philosophy faculty of Charles University in Prague. He became the head of the first independent students' association and was active in a Catholic youth group. By the time he graduated in 1969 the post-invasion "normalisation" was under way, crushing the remnants of public independent activity. Benda and his wife Kamila had decided during the Soviet-led invasion of August 1968 not to flee the country.
He remained at Charles University, completing his doctorate in theoretical cybernetics in 1975, and published works on philosophy and mathematics. He then worked as a computer programmer. This official activity ceased in 1977, the year that saw the launch of Charter 77, the dissidents' manifesto Benda was so closely involved in.
Benda was one of the first signatories and - like many others - suffered immediate official retribution. He was sacked from his job and was forced to become a stoker (what would become a traditional occupation for dissidents).
He published numerous writings as typewritten texts in samizdat, ranging from philosophy to politics to literary criticism to poetry and even a novel, Cern Dvka ("The Black Girl", 1978). Benda's theoretical works were instrumental in developing the opposition's ideas. His 1978 essay Paraleln Polis ("The Parallel Polis") articulated the aim of creating an independent, civil society outside the confines of state ideology which became a cornerstone of Charter thinking.
He was merciless in his criticism of the roots of state power. "By proclamation the system has elevated the stick and carrot from being a mere means of government to an ideological principle and this guarantees the state authorities and their doctrine a secure power base," he wrote in the 1970s. "However, this system faces one mortal danger - it is based on the assumption that everybody must recognise the stick and carrot as an argument. The cry that the emperor is naked can lead to quite uncontrollable and unexpected consequences."
As the dissident movement crystallised, Benda went on to help found in May 1978 a Charter offshoot, the Committee for the Defence of the Unjustly Prosecuted, which documented in meticulous detail the cases of those suffering repression for their political, human rights or religious activity.
In January 1979 he became one of Charter 77's three official spokesmen and in March he and his wife were charged with subversion, though not arrested. Benda was detained in May and sentenced the following October to four years' imprisonment.
Although he found prison hard, he resolutely refused the secret police's constant offers to sign a statement admitting that he had broken the law in return for release and passage out of the country. The deal foundered not only on Benda's obstinate refusal to compromise, but on the secret police's inability to find a law that he might have broken.
Prison did not dent his commitment to fight the regime and he renewed his activities immediately on release. In 1984 he again became a Charter 77 spokesman. Harassment was constant: his flat was repeatedly ransacked by the secret police and in total he was subjected to 13 spells of house arrest in 11 years.
For eight years he was denied a phone and secret police watched his door. His children were barred from studies of their choice and at least one was threatened with "disappearance".
As Communist rule crumbled across Eastern Europe in 1989, Benda played a key role in the meetings at the Magic Lantern Theatre in Prague which formed Civic Forum, the movement that took over the government as the Communist regime gave up.
Benda was determined to purge Czechoslovakia - and after the split, the Czech Republic - of lingering Communist influence. In January 1991 he proposed that all members of parliament and senior government officials be screened to root out collaborators with the secret police (a proposal rejected only by the Communists). Thanks to his anti-Communist credentials, Benda was put in charge of the Office for the Documentation and Investigation of the Crimes of Communism on its creation in 1991, a job he held until January 1998.
Benda created an international uproar last year by suggesting that Helmut Zilk, a former mayor of Vienna, collaborated with the Czechoslovak secret police in the 1960s. The claim led the Czech President Vclav Havel to withdraw the highest state honour just days before it was to be given to Zilk. A subsequent investigation found that Benda's allegations were unfounded and Havel publicly apologised to Zilk. In April of this year, the Senate refused to strip Benda of his parliamentary immunity, thereby preventing him from being prosecuted in connection with his allegations.
The final straw for many came with his vocal support for the embattled former Chilean dictator Augusto Pinochet, whom he had once invited to lunch during a visit to Prague. After Pinochet's arrest during his visit to Britain for medical treatment and threatened extradition to Spain to face charges of crimes against humanity, Benda signed a letter to the British press calling for his release. Critics complained that Benda failed to see that Pinochet's repressions were far more vicious than those of the Czechoslovak regime of the 1970s and 1980s.
Bearded, portly and a heavy smoker, Benda was immediately recognisable at any gathering. He was also adept at finding humour in his numerous encounters with the sometimes less than intelligent secret police. He was a devoted family man, and the long-suffering Kamila had to bear a heavy burden for her marriage to such a single- minded and tenacious man.
"The conflict with the state into which I have entered will be long, exhausting and, by all human standards, hopeless," he wrote of his life in the 1970s. "In this country this means that my whole family down to the third generation will also be brought into the conflict, together with all my friends who were not quick enough to disown me publicly."
But Vclav Benda went on to describe how police raids had become a "welcome adventure" for his children, who loved to play the games "Belonging to the Charter" and "Being Unemployed". Three of these children have taken up politics.
Vclav Benda, mathematician, philosopher and politician: born Prague 8 August 1946; married 1967 Kamila Neubauerov (four sons, two daughters); died Prague 1 June 1999.