The idea that one should not philosophize keeping close contact with empirical facts, instead of basing a long chain of arguments on abstract “logical” principles like Leibniz’s, may be almost common sense now, but it wasn’t in the early modern period of which Russell was talking about. And when Russell wrote this (1940s) he was old enough to remember that these kind of arguments were still prevalent in his youth (1880s-1890s) among absolute idealists like Bradley, as he describes in “Our Knowledge of the External World” (follow the link and do a Ctrl-F search for Bradley). So it did not seem to him a way of thinking that was so ancient and outdated as to be not worth arguing against.
ETA: I meant, “The idea that one should philosophize keeping...”, without not, obviously.
The idea that one should not philosophize keeping close contact with empirical facts, instead of basing a long chain of arguments on abstract “logical” principles like Leibniz’s, may be almost common sense now, but it wasn’t in the early modern period of which Russell was talking about. And when Russell wrote this (1940s) he was old enough to remember that these kind of arguments were still prevalent in his youth (1880s-1890s) among absolute idealists like Bradley, as he describes in “Our Knowledge of the External World” (follow the link and do a Ctrl-F search for Bradley). So it did not seem to him a way of thinking that was so ancient and outdated as to be not worth arguing against.
ETA: I meant, “The idea that one should philosophize keeping...”, without not, obviously.
Ah very good, in that context it makes perfect sense.