Liberal Democrat leader Sir Menzies Campbell and Labour MP Tam Dalyell are among the figures attending Edinburgh's second Festival of Politics.
George Reid said the festival would cater for almost every taste
The Scottish Parliament's Presiding Officer George Reid got the event under way on Wednesday.
Sir Sean Connery pulled out of his planned appearance after Mr Reid said he would question the actor on his views on violence towards women.
The event runs until Saturday, with a host of famous faces taking part.
Those appearing at Holyrood include newsreader George Alagiah, TV historian Dan Snow and comedian and writer Armando Iannucci.
The programme will include debates on the Middle East, Culloden, Scottish identity and the health of political democracy and entrepreneurship.
There will also be live performances from award-winning Scottish folk singer Karine Polwart, Hollywood actress Tommie Stewart and US singer-songwriters Emma's Revolution.
Festival-goers will be able to view the world press photo exhibition, containing more than 200 images taken by leading photojournalists of major events in 2005.
The festival has doubled the number of events from last year to almost 50 and Mr Reid said it would cater for almost every taste.
Mr Reid said: "This year's Festival of Politics has almost double the number of events and includes an extra dedicated family day.
"From hard-hitting political debate to cutting-edge comedy along with multi-cultural dance and home-grown Scottish folk music, our diverse programme contains something for everyone."
Sir Menzies, the Fife North East MP and former Olympic athlete, will be talking about his life in politics and his vision for the Lib Dems during a talk with the presiding officer on Thursday.
On the same day Mr Dalyell, the former father of the Commons, is expected to re-visit the West Lothian question which he first raised in the 1970s, questioning the right of Scottish MPs to vote in Westminster on matters devolved to a Scottish Parliament.
Scottish Green MSP Chris Ballance will chair a festival debate on the role of the media in conflict and peace on Thursday.
Those due to take part in the debate include Professor David Miller from Strathclyde University; Hugh Miles, Times Young Journalist of the Year and the Muslim Association of Britain's Osama Saeed.