Dennis Canavan said Holyrood's opposition parties "owe it" to Scots to develop and present policies for an independent Scotland.
In an article for HeraldScotland, the former Labour MP and Independent MSP accused Labour, the Tories and Lib Dems of simply "hoping for a No vote".
His comments were dismissed by Alistair Darling, the head of the pro-UK Better Together campaign, who said it was for the Nationalists to explain "exactly what separation would mean".
Mr Canavan, who chairs the pro-independence group's advisory board, made his plea after Deputy First Minister Nicola Sturgeon appealed to voters to make a "pragmatic" decision for independence.
She announced that pro-UK parties would be given a say in crucial negotiations with the rest of the UK which would shape an independent Scotland in the event of a Yes vote.
Mr Canavan's comments also echo those of Clyde Blowers entrepreneur Jim McColl, who urged pro-UK parties to reveal their visions of an independent Scotland.
The former MSP writes: "The anti-independence parties – Labour, Conservative and Liberal Democrats – owe it to the Scottish people to reveal their visions for Scotland in the event of a Yes vote in 2014. As the proponents of change, we in Yes Scotland have a duty to spell out why we believe Scotland would benefit from being independent and why it would enable us to build the kind of country that matches our values and priorities.
"Equally, our opponents have a responsibility to explain why they think the UK remains the better option for Scotland rather than just aimlessly attacking self-determination.
"The Scottish Government has said it will lay out its vision in a White Paper next year. But the people of Scotland deserve to know what all parties would do in an independent Scotland. It is simply not good enough to ignore it in the hope that there will be a No vote."
Former Chancellor Mr Darling said: "This is typical of the nationalists of late.
"They have no answers to any questions, so they either accuse people of scaremongering or try deflect away from their deficiencies by trying to turn the spotlight on others.
"We don't want to separate Scotland from the rest of the UK. We are not planning to break up Britain.
"The Nationalists are the ones who want us to take this gamble and it is for them to explain to people exactly what separation would mean.
"We do have a vision for the future. We believe that we can have the best of both worlds. A strong Parliament in Edinburgh working with the Parliament in London to make lives better for the people of Scotland. This is a vision that the majority of Scots can buy into."