On Friday, Ireland will vote on whether to remove a single sentence which enshrines a near-total ban on abortion in the constitution, even in cases of rape and fatal foetal abnormality. The eighth amendment underpins the strictest controls in a western democracy, placing the “right to life of the unborn” on a par with the life of the mother.

This is, as it must be, Ireland’s decision. But its impact will not end there. It will be felt first in Northern Ireland, with its own punitive laws, and then globally. The influx of cash from foreign anti-abortion groups shows that the vote must be understood in the context of efforts to roll back rights, from the US to Brazil to Poland. A yes vote would hearten those resisting the pressure, a no vote embolden those trying to ban safe, legal abortions. Moreover, the amendment exports rather than halts abortions. In recent decades more than 150,000 Irish women have travelled to have abortions, mostly to England. Others use smuggled pills, risking prosecution if they subsequently need medical attention.

For the truth is that voters are not deciding whether women should have abortions, but where they have them and under what circumstances. The eighth amendment merely creates unnecessary trauma for women and denies abortion to a small number who are in the most difficult circumstances – unable to travel due to their immigration status, poverty, a controlling partner, or their medical condition. That bar has even proved fatal: Savita Halappanavar died from septicaemia following a miscarriage, having been repeatedly refused an abortion. Though her death led to a new law allowing abortions where the mother’s life is at “substantial” risk, the shock it caused nonetheless galvanised the push for more fundamental reform.

These are the uncomfortable realities of the current system. Set against them are of course deeply rooted moral convictions, but also a no campaign fuelled by myths and downright lies. Proposed new legislation would ensure that controls remained on access to abortion. Liberalisation would not result in the widespread abortion of foetuses with Down’s syndrome, as doctors have made clear. And it is not only insulting but flagrantly untrue to suggest that women will seek abortion on a whim.

These attempts to twist facts and stoke sentiment reflect a reactionary, cynical populism familiar from the pro-Brexit and Trump campaigns. Save the Eighth campaigners have urged the public not to trust politicians and have painted themselves as brave anti-establishment voices, latching on to a half-truth: for Ireland has indeed undergone a profound shift in its social attitudes, and what was once controversial now looks like common sense to many. In 1983, 67% of voters supported introducing the amendment. This time, the outcome is too close to call. The taoiseach, Leo Varadkar, has campaigned for yes, though less vigorously than many had hoped. Fianna Fáil originally proposed the eighth, yet its leader Micheál Martin has vocally supported repeal (to much of his party’s dismay). A righteous, shining anger at centuries of misogyny has burned in this campaign. Widespread disenchantment with the church for its moral failures, from turning a blind eye to sexual abuse, to the Magdalene laundries scandal, has underlain the change. Yet the yes campaign has wisely avoided portraying this as an unbridgeable cultural rift between millennial urbanites and older rural dwellers, promoting hashtags and groups such as #farmers4yes and “grandparents for repeal”.

Even so, initially promising polls have narrowed dramatically. A fifth of voters remain undecided and turnout will be crucial. If Ireland votes no, another generation of Irish women will suffer, and the cause of women’s rights globally will be set back. If it votes yes by a narrow margin, anti-repeal politicians will feel entitled to play havoc with the proposed legislation, whittling away the gains. Either result would give heart to all those seeking to manipulate public opinion instead of informing it. All these are reasons for Ireland to vote yes, and to do so wholeheartedly. Yes to compassion. Yes to valuing women and their fundamental rights. Yes to repeal.