Minister for Finance Brian Lenihan and former taoiseach Bertie Ahern will disagree fundamentally on the causes of Ireland's domestic economic crisis in the RTÉ documentary Freefall tomorrow night.

The second part of the programme will look at the way the economic bubble burst and charts the course taken by politicians, bankers, regulators and developers.

Explanations for Ireland having one of the hardest landings in the western world after the bubble burst show Ahern blaming external international circumstances.

Lenihan, who was not at the cabinet table when Ahern was taoiseach, admits: "We became too dependent on construction as the main motor and engine in the economy …"

But Ahern sticks to the line he has trotted out throughout the recession: "If Lehman's didn't collapse then we wouldn't have had the hard landing … and because of the international situation we didn't get that, which blew a bubble we otherwise probably could have got away with."

Economist Jim Power remarks in the programme that "for Ireland the collapse we have seen in the economy and financial system is the biggest collapse that has ever occurred in Irish history".

Much of the programme focuses on developers. Michael O'Flynn, managing director of the Flynn Group, says: "By and large developers are a hard working grounded group of people, who have generally built up their businesses from scratch. The nature of developers is to put their chips back on the table and keep going."

O'Flynn adds: "The banks were the fuel of the property economy, let's have no doubt about that – we never asked the question could the bank afford to give us the money. We all thought there were people in an ivory tower figuring out the bigger picture whilst we all got in with the game at hand."

Richard Barrett of Treasury Holdings provides a good insight into how property prices soared. He explains that even though land in Dublin 4 became the most expensive land on the planet, there were always people willing to bet on that price level rising further. He also points out that as well as reckless lenders fuelling the bubble, there were reckless borrowers that are just as culpable.

But Ahern is still reluctant to deride developers and says, "Maybe they weren't wise in some of their commercial decisions, but lots of other people weren't wise in their commercial decisions either and I don't go with the thing of just dancing on their graves."