 A bit more serious is Putnam’s (1962) objection drawing on the application of apparently clear-cut instances of observation concepts to submicroscopic particles. Here, Carnap would have to distinguish between color concepts applying to observable entities and related color concepts applying to unobservable ones. So, the formal language in which the logical analysis proceeds would have to contain a predicate ‘red\(_1\)’ applying to macroscopic objects and another one ‘red\(_2\)’ applying to submicroscopic ones. Again, such a move would be in line with the artificial, or ideal language philosophy that Carnap advocated (see Lutz (2012) for a sympathetic discussion of artificial language philosophy).