from Let’s Get Metaphysical About Trump and the ‘Post-Truth Era’ by Crispin Sartwell

Likewise, truth cannot be a matter of social consensus. That groups are in agreement has no tendency to show that what they believe is true, or else flat contradictions are true in a situation in which we are polarized into groups with contradictory beliefs. As consensus tightens, it degenerates into self-confirmation and collective delusion. Each side already believes this about the other, so each side is committed to the view that truth is something more than agreement. Nor can “truth” mean merely what works, if by “works” one means persuading people or guiding their behavior or opinions in some desirable direction.

That makes it very odd to formulate the thing in terms of alternative realities or the disintegration of truth itself. Both sides need the truth, and they need it not to be relative to any group’s particular set of beliefs—or they need to stop attacking their opponents. There’s nothing unusual about a situation in which people disagree about what the truth is, and the concept of truth itself is not particularly at stake right now.

It’s a bizarre misapprehension, in short, that truth is disintegrating or in crisis. Fabrications do not undermine truth—they presuppose it. Lies can harm people, but they can’t harm truth itself. They conceptually depend on it. The right conclusion from all this isn’t that truth is disintegrating, but that truth is hard and intrusive, that it does not readily bend to human will or agreement or narrative. The power of the Russian intelligence services or a Sean Spicer press briefing is considerable, but it does not include the ability to bend the fabric of reality.