Nobel laureate Amartya Sen on Monday stressed on the need for opposition unity in India to protest against a cause. But, he added, even if there was no unity, protests must continue.

“For any kind of protest, opposition unity is important,” Sen told journalists on Monday night when asked about the protests against the amended Citizenship Act, the National Population Register and the National Register of Citizens. “Then protests become easier. Unity is important if the protest is for a proper cause.”

He added: “But even if unity is not there, then that doesn’t mean we will stop protesting. As I said, unity makes protest easier but if unity is not there still we have to move on and do whatever is necessary.”

Earlier in the day, he had said it would be a mistake to view oppositional reasoning as merely quarrelsome. “It is necessary to emphasise the subtleties of the innovative forces of the opposition,” he said at the Nabanita Deb Sen Memorial Lecture in Kolkata. “We need to know more about what I am protesting about. The head must also join with the heart in protest.”

He added: “When there seems to be a big mistake in the Constitution or human rights, there will surely be reasons to protest.”

Sen’s comments came on a day some Opposition parties in India met to discuss the citizenship law and protests related to it. The Trinamool Congress, Bahujan Samaj Party, the Dravida Munnetra Kazhagam, the Aam Aadmi Party and the Shiv Sena skipped the event.

Twenty Opposition parties attended a meeting in New Delhi convened by Congress President Sonia Gandhi. They passed a resolution calling on the Bharatiya Janata Party government to withdraw the amended citizenship law and stop the National Register of Citizens and National Population Register projects.

The resolution said: “The CAA, NPR and NRC is a package that is unconstitutional, which specifically targets the poor, the downtrodden, the Scheduled Castes/Scheduled Tribes and the linguistic and religious minorities. We demand the withdrawal of the CAA and the immediate stoppage of the nationwide NRC/NPR.”

They appealed to non-BJP chief ministers, who had announced not to carry out a proposed nationwide NRC, to suspend the exercise of enumeration of the National Population Register exercise, alleging that it is a prelude to the citizens’ register.

Last week, Sen had said the amended citizenship law was unconstitutional and that the Supreme Court should turn it down. “You cannot have certain types of fundamental rights of human beings, in this case connected with citizenship, be related with religious differences rather than the things that really matter such as where you were born, and what the citizenship laws require you to do,” he had said.

Sen said there was need for sympathy. “Muslims in Burma [Myanmar] should be given exactly the same consideration as of maltreatment of Hindus in some other country,” he had added. “It has to be independent of religion, but take cognisance of other serious reasons to apply for Indian citizenship. It should be granted on fair, just and equitable basis and not on the basis of communal discrimination against one religion.”

The Citizenship Amendment Act, approved by Parliament on December 11, provides citizenship to refugees from six minority religious communities from Bangladesh, Afghanistan and Pakistan, provided they have lived in India for six years and entered the country by December 31, 2014. The Act has been widely criticised for excluding Muslims.