Liberals often pride themselves on being on the "right side of history". I wonder: how do they, how do we know what the "right" side is?
Is it simply "more freedom for everybody"?

Just one example: in the wake of the sexual revolution of the swinging sixties, paedophilia was considered among Progressives to be just another variant of sexuality. And the zeitgeist of that time was: freedom for the paedophiles!

In 1977, a petition to the French parliament calling for the decriminalisation of sex between adults and children was signed by a long list of famous intellectuals, including Jean-Paul Sartre, Jacques Derrida, Roland Barthes, Simone de Beauvoir (!), Gilles Deleuze, Félix Guattari and – that esteemed radical and father of Queer Theory – Michel Foucault.

In Britain, members of the Paedophile Information Exchange were openly campaigning for the abolition of the age of consent and found themselves welcomed warmly in some establishment circles. In the United States, NAMBLA (the North American Man Boy Love Association) was founded at the end of the 1970s and attracted support from figures including the poet Allen Ginsberg and the feminist Camille Paglia.

All these people were very much in favor of Progress, and I'm sure that they saw themselves, just like Progressives today, to be on the right side of history. Today, we call it child abuse and nobody, except some weirdoes, still campaigns for its legalization.

So here's my question again: how can we tell the wrong and the right side of history apart? Could it be that today's Progressives and Liberals are now as much deluding themselves about their current issues of progress being made as were those heroes of Social Justice I mentioned above about sex with children ?

(Edit: My guess is that it is just the winning side of cultural / political evolution which proclaims "We are the right side of history". As liberals are currently on the rise, they also claim the right to define the "right side" )