Fianna Fáil have tabled a Dáil motion calling for anomalies in the contributory State pension to be corrected.
The party's Social Affairs spokesman, Willie O'Dea, said he found it very difficult to explain to anyone how a system can provide two different rates of pensions to people who paid the exact same amount of contributions.
"It's meant to be based on the more you put in, the more you get out," Mr O'Dea told the Dáil.
The motion also calls for the current eligibility criteria for pension entitlement to be examined and band changes from 2012 to be reversed.
Mr O'Dea said the Taoiseach himself had conceded that the present system is anomalous and gives rise to injustice.
He said the situation could be described as cruel, callous, and perhaps unconstitutional.
He said he was not insisting the Government conjures up hundreds of millions to go back to 2012, but they wanted to immediately begin the process of removing the discriminatory provision, as far as it affects those born after 1 Sept 1946.
He said he wanted a specific timescale for addressing the matter, rather than reports.
Sinn Féin accused Fianna Fáil of a PR stunt by presenting a motion to correct anomalies in the scheme.
John Brady said Fianna Fáil did not support a Sinn Féin motion on the same issue and claimed they were now crying "crocodile tears."
However, he said they would support the Fianna Fáil motion, adding an amendment to address the issue of those aged 65 who have to claim Jobseeker's Allowance.
Mr Brady said the proposed overhaul of the total contributions method from 2020 would only apply for new entrants.
Labour's Willie Penrose said his party would be supporting the motion
Deputy Penrose said the 2012 changes, which he acknowledged were introduced by the then tánáiste Joan Burton, had to be addressed and some of the adjustments were "regrettable".
Minister for Social Protection Regina Doherty put forward a counter-motion outlining the challenges faced in formulating pension policy and indicating the general approach Government will take in the future to introduce equity into the system.
She said pensions are diverse and complex and that is reflected in the Fianna Fáil motion.
Ms Doherty said that spending on State pensions has increased rapidly in recent decades, from €1.7bn in 1997 to €4bn in 2007, increasing to €7.3bn this year.
She said after adjustment for inflation this amounts to an increase in real terms of 76% during ten of the most difficult economic years this country has ever seen.
The Meath East TD noted that without the increase in the State pension age in 2014, the rising cost of would have been even more dramatic.
She said spending is expected to increase by €1bn every five years.
She added that the Fianna Fáil proposals would cost almost €73m in 2018 alone, increasing to almost €85m in 2019 and would continue to increase every single year thereafter.
Ms Doherty also said "the 2012 rate band changes resulted in a system that more closely aligns a person’s benefit with their social insurance contribution history. In addition the revised system continues to provide very generous pensions compared to the norms in other countries.
"For example, a person with only 20 years contributions over nearly 50 years will still attract 85% of a full pension, which is substantially higher than could be expected in any other EU country, including those with very generous homemaking provisions."
The minster agreed that the position of women who left work to take up care and responsibilities is a very special case, but said we have to be careful that the solution we use to address this special case does not impose any unnecessary or unjustifiable costs on our future workers.
She said the extension of PRSI over the years means we can move to a more equitable total contributions approach from around 2020.
She repeated that it is impossible to make specific proposals until the analysis of all paper records takes place.
Solidarity/PBP TD Paul Murphy said it should be clearly acknowledged that Ms Burton implemented the cuts.
He said Fianna Fáil could have argued with the Government during the Budget negotiations and made this an issue of principle. He said that they did not do this.
He called on Fianna Fáil to vote against the Social Welfare Bill and that will be test of the sincerity of Fianna Fáil on this issue.