 Lange concedes that Czolbe’s materialism, were it to actually be supported by empirical evidence, is in principle able to avoid undermining itself. To Lange, though, Czolbe has to twist the empirical evidence, and so Czolbe’s materialism ultimately does undermine itself. Lange accuses Czolbe of being obstinate and treating the results of scientific investigations in an unscientific manner, as mere illusions that would disappear on closer examination (Lange 1873–75, 2:291).