Senator David Norris has said that criminalising the purchase of sex would not protect sex workers.
The call comes after Amnesty International voted earlier this week to create a plan to protect sex workers, rather than punish them.
At their International Council Meeting in Dublin earlier this week, delegates also recommended that they support the full decriminalisation of all aspects of consensual sex work.
The charity says that they recognise that it is a complex issue, but added that it is also a critical human rights issue internationally.
Sex Workers Alliance Ireland (SWAI) said in a statement that they were 'delighted' with the passing of the Amnesty resolution.
In Ireland, buying or selling sexual services is currently not illegal, but certain activities associated with prostitution are.
Independent Senator Norris - who is in favour of Amnesty's vote - says people have been making themselves available for sexual gratification in return for money since time began.
Criticising Government plans to criminalise the purchasers of sex, he said, "I've never heard anything more ludicrous than the idea that the law can outlaw one half of a transaction, and legalise the other. It's complete and utter nonsense".
Speaking to Colette Fitzpatrick on Newstalk Lunchtime today, he said "we drive it underground where it is extremely dangerous for the sex workers involved.
"All these self-righteous do-gooders, do they actually think that prostitution will end? Of course it won't," he added.
Mr Norris made the comments during a discussion on the topic with Sinn Féin TD Pádraig Mac Lochlainn, who supported the 'Nordic model' where the purchaser of sexual services is criminalised.
The model is supported by groups such as the Turn Off the Red Light campaign.
Deputy Mac Lochlainn said, "prostitution by its very nature is underground. The fact is that its carried out in apartments and brothels across Ireland, mostly foreign women brought in here for that purpose.
"What we need to do is have a debate, particularly among Irish men, about 'what right do you have to purchase the body of a woman?'" he added.
You can listen back to the full debate below, where Senator Norris started by discussing legislation outlawing the purchase of sex:
