I can sympathize with that. There will always be one point in a discussion where the participants get to a disagreement about their fundamental philosophical stances - and that's a positive: it allows us to see the discussed topic from different angles. And laying out one's most basic views (while also always revealing one's intellectual weaknesses) makes it easier for others to empathize. So, in short on, on our differences and overlaps:Novalis wrote: I think this is where I disagree then.
Originally I started writing a very long reply trying to lay out my position vis-à-vis internal talk with reference to Bahktin, Blanchot, Heidegger and Wittgenstein, and then realised that this conversation would be far too overpowered for what is needed here. I'll just paraphrase the general gist and leave it there: one is never less alone than when alone.
Far cleaner and closer to the source for our purposes is the work of Martha Nochimson.
Nochimson does a good job in excavating Lynch's belief in a Unified Field theory. In Lynch's view the highly personalised readings of individuals, when meditated upon should all point (on the 'deepest level') to this unified field.
As an avowed materialist I don't buy any brand of mysticism of course (and believe me I spent a whole decade of my life up to my eyeballs in it): for me the social element, which consists of both contestation and agreement, takes place in external space, in public language use, and not in solitary meditation.
As a person with a lot of vested interest in writing about artists and their artwork, I would venture that we can assume Lynch's position, understand its context, and to some extent understand his motivations, without necessarily having to believe what he believes. The problem of other minds is for me a philosophical red herring that means we could never get started with such an enterprise, and which in practice cancels itself out.
I'm not a spiritualist either, nor do I have any solipsist or idealist views (thus, the sentiment "alone in our minds" is not to be read as an absolute). Categorizing myself, I'd say I come closest to being a Kantian and as such, I am a realist and cannot be an exclusive materialist, as I need my "a priori", some kind of pure conceptualism (at least for mathematical concepts and regulative ideas). This also makes me a dualist, but not with the old material/spiritual-dichotomy but with empiricism vs. conceptualism.
Other than that, I revere the greeks, abhor most of the romans and the medieval scholars, and have some respect for the modernists. Concerning Anglo-American analytical philosophers, I love their methodology but dislike their general lack of historical awareness.
All in all, I guess we do agree on some of the results, though: The "social element" can not be regarded highly enough. And whether or not we can completely get into someone else's state of mind, I do agree we can get close enough to understand them (and I think, as a conceptual realist, that's even easier for me to rationalize than for a pure materialist ^^). That does mean that, indeed, it should (at least theoretically) be possible to understand Lynch and "assume his possition", as you said. But he doesn't make it easy for us to do so.
His context and motivation, I do find interesting, and those are certainly helpful to immerse into the person "David Lynch" - yet I'd abstract from them when trying to explore his work. I feel, for example, that decades of this personality-centered approach have been more of a hindrance than a help to the mainstream Kafka research.
Knowing more about Lynches philosophical foundations, however, could help. But other than being a spiritualist (probably without adhering to a specific religious doctrin) he seems to get most inspiration from eastern philosophy and: 1) I'm not an expert in eastern philosophies. 2.) Many of these are more on the practical side of philosophy, thus allowing for many different intellectual groundworks.
Oh, and one last point on your "internal talk": I'd claim that Heidegger is never too overpowered or inappropriate for any topic whatsoever. Heidegger heideggers!