by one's own lights

[okok]

Hello. In a text about a religious thinker trying to disprove the philosophers I read that according to him, the philosophers "were incoherent by their own philosophical lights." What does that mean? That their own methods (the light by which they see their way) led them to incoherence?

[MrPedantic]

Hello Okok

It means that if the methods that those philosophers advocate are applied to those philosophers' own philosophies, their philosophies are found to be incoherent.

MrP

[okok]

Thank you very much. It makes sense.