Because it actually does mean something, even if we don’t really know what and borders are fuzzy.
When you hear that X is more intelligent than Y, there is some information you learn, even though you didn’t find out exactly what can X do that Y can’t.
Note that we also use words like “mass” and “gravity” and “probability”; even though we know lots about each, it’s not at all clear what they are (or, like in the case of probability, there are conflicting opinions).
Because it actually does mean something, even if we don’t really know what and borders are fuzzy.
When you hear that X is more intelligent than Y, there is some information you learn, even though you didn’t find out exactly what can X do that Y can’t.
Note that we also use words like “mass” and “gravity” and “probability”; even though we know lots about each, it’s not at all clear what they are (or, like in the case of probability, there are conflicting opinions).