The second round of the leftwing presidential primary last weekend showcased two diametrically opposed concepts of French secularism. The victory of the rebel outsider Benoît Hamon marked the rejection by leftwing voters of the version of secularism fiercely defended by the former Socialist prime minister Manuel Valls.

French Socialists choose leftwing rebel Benoît Hamon for Élysée fight Read more

Having won the first-round vote, Hamon, the Socialist MP for the Paris suburb of Trappes and a former education minister, went out of his way in the run-up to the second round to focus on what has become one of the most contentious issues both in the Socialist party and across French politics.

French secularism is based on three core principles guaranteed by what is known as “the 1905 law”: freedom of conscience and religion; clear separation between church and state; and equality before the law. The law was adopted under the Third Republic and was a compromise between secular and religious groups, and MPs on both sides.

But disagreement on its interpretation continues and has reached a new pitch in recent years: from the expulsion in 1989 of three Muslim girls after they refused to take off their Islamic headscarves at school, to the 2011 outlawing of the full-face Islamic veil in public places, and last summer’s “burkini ban” – which was backed up by Valls, then prime minister.

Recent Islamic terrorist attacks have transformed this debate and placed it at the heart of this year’s presidential campaign. In France today serious debate on the place of religion in society has been replaced by an argument about whether Islam is compatible with a secular democracy, with the Front National’s Marine Le Pen continually attacking Muslims for alleged infringements of secularism, and insisting on France’s “Christian roots”.

Facebook Twitter Pinterest ‘Valls’s position echoed that of François Fillon (pictured)’ Photograph: Christophe Ena/AP

Valls, a potential president before his crushing defeat last Sunday, was an upholder of laïcité stricte, or “stringent secularism”, a stance widely emulated across the French political spectrum.

During debates and public meetings, he hammered away at the need to fight communitarianism, a term used in France to describe inward-facing communities – invariably meaning Muslims. Valls also reaffirmed his hostility to the Islamic veil he describes as a “symbol of women’s enslavement”. He also proposed a charte de la laïcité (secularism charter), and rejected any kind of accommodements raisonnables – a term used in Canada to describe actions by the state to take account of religious minorities.

Paris knife attack: soldier shoots man outside Louvre in 'terrorist' incident Read more

Valls’s position echoed that of François Fillon, the Catholic rightwing candidate now engulfed in a scandal over allegations of payments to family members. He once said: “There is no religious problem in France, there is a problem with Islam.” By contrast, Hamon’s victory has brought back to life a laïcité ouverte, or soft secularism, which seemed in recent years to have disappeared.

Of course, Hamon’s chances of becoming president are slim, with Emmanuel Macron, the independent candidate and former economy minister, and Le Pen both more likely to reach the second-round runoff in May. But Hamon’s presence at the forthcoming debates alongside Macron, who has kept his focus on economic issues but also criticised the “marginalisation and stigmatisation of Islam”, will at least mean an alternative view of the future of French secularism is heard.

If Hamon can continue to distance himself from more aggressive forms of secularism, he might help pave the way to a new approach that acknowledges France has become a multicultural society, inside the Socialist party and beyond.