There's nothing magical about the particular word/symbol/phoneme-sequence "dog", of course. In German, they say _Hund_; in Finnish, they say _koira_; in Korean, they say _개_. Germans and Finns and Koreans (and their dogs) seem to be getting along just as well as we Anglophones.
Nevertheless, it is a fact _about contemporary English_ that "dog" means dog. If you thought this was bad for whatever reason, and you wanted to change that fact, you'd have to change the behavior of actually-existing English speakers. If you tried to stipulate on your Facebook wall that the word "dog" should mean _tree_ now, and all of your Facebook friends nodded in agreement at your clever argument _and then continued to call dogs "dogs" and trees "trees" in their everyday life just like they always had_, then your language reform attempt would have, _in fact_, failed—even if the fact that it failed would be less obvious if you only looked at the Facebook thread full of people nodding in agreement.
There's nothing magical about the particular word/symbol/phoneme-sequence "dog", of course. In German, they say _Hund_; in Finnish, they say _koira_; in Korean, they say _개_. Germans and Finns and Koreans (and their dogs) seem to be getting along just as well as we Anglophones.
Nevertheless, it is a fact _about contemporary English_ that "dog" means dog. If you thought this was bad for whatever reason, and you wanted to change that fact, you'd have to change the behavior of actually-existing English speakers. If you tried to stipulate on your Facebook wall that the word "dog" should mean _tree_ now, and all of your Facebook friends nodded in agreement at your clever argument _and then continued to call dogs "dogs" and trees "trees" in their everyday life just like they always had_, then your language reform attempt would have, _in fact_, failed—even if the fact that it failed would be less obvious if you only looked at the Facebook thread full of people nodding in agreement.