I can see how private language does not make sense in Wittgensteins eyes, in that a language in its true sense cannot be with one person, but I don’t see how this is relevant to mind/body dualism? I see lots of people saying that a ‘language’ that is ‘private’ suggests mind/body dualism is not real, but all I see is the feeling of senses cannot be described in a (soliloquised, for lack of a better word ‘language’) doesn’t mean anything except a private language is not possible.
Note: I’ve never asked a philosophical question online before, and I’ve also had a couple of beers as England have just got to the QFs of the World Cup so if this makes no sense I will try to reword!
You should study Wittgenstein's arguments against a private language more closely, because I don't think that his view is quite that language "cannot be with one person", although that is really a wonderful way of putting it. It seems to suggest merely the view that the nature of language is that of a interpersonal communication, which is a bit uninteresting, and yet your phrasing is profoundly interesting. I also didn't quite follow why thinking that there can be a private language goes against psychophysical dualism. Surely it's the other way round. Descartes, for example, has to think he can give sense to his words privately, because he can intelligibly doubt the existence of everyone else. And Wittgenstein himself has been thought to be a behaviourist, or closer to behaviourism than to psychophysical dualism. I am very sorry about Croatia too. I imagine you had some more beers. I did.