President Pranab Mukherjee said on Thursday that the freedom to doubt, disagree and dispute intellectually must be protected as an essential pillar of Indian democracy."Nothing should lie outside the realm of reason, and therefore of discussion and argument. Such freedom is vital for progress in any field, especially a calling and a craft like history," Mukherjee said while inaugurating the 77th session of Indian History Congress here.The President said an objective pursuit of history requires an impartial mind of a judge and not the mind of an advocate. "We must keep our eyes open for unfamiliar ideas and be ready to consider a range of different inferences or assumptions. This necessarily bars intolerance of contrary opinions or judgements," he said.Mukherjee said that there has been an unfortunate tendency in the country from time to time to take umbrage at the expression of any view perceived to be hostile to social or cultural institutions, past or present. "Similarly, critical appraisals of our heroes and national icons of the past have been met with hostility and sometimes even violence," he said adding that "the freedom to doubt, disagree and dispute intellectually must be protected as an essential pillar of our democracy".