Ted, I agree with you about the parallel between notions of Authenticity and the notions in Marx which you point out. Your explication of Marx is also well done. One can find such parallel notions in many philosophers expressed in various ways.
But the difference between Marx and Heidegger is that it is possible to express in "everyday" terms Marx's notion as a relation between human species "potential" (both individually and collectively, what we are and what we can be, as fully realized human beings) and the social relations that might allow for such a "development." This is not possible for Heidegger. Heidegger's notion of authenticity is not an historical predication, nor is it an empirical conclusion about possible human development based on the nature of the human species. For instance, it does no real harm to Marx's thought to assume a Darwinian notion of hominid evolution or a Chomskian notion of language. Marx would have welcomed (and as much as he understood Darwin did welcome) such "scientific" developments, if he was convinced that they were interpreted correctly and had not been over-generalized for ideological purposes. ("Social Darwinism" would be an example of such an over-generalization.) "Human potential" to reach the "true realm of freedom" was an historical and practical matter for Marx.
The same cannot be said for Heidegger in this regard. And the contrast is not irrelevant to the notion of authenticity as used by Heidegger, nor to Carrol's implied criticism of that notion.
For instance, Chris Doss said of authenticity: "In Heidegger specifically, authenticity (Erschlossenheit, which does not translate literally as "authenticity") is a technical term referring to when the perceived available life-possibilities coincide with the real available life-possibilities. This is why it is connected to truth, and to death and finitude, and to being-one's-self." This is an adequate definition but it deemphasizes the main point that Heidegger is trying to make, which is, in the first place, about human existence as such. Unlike Sartre, Heidegger is not "using" his ontology in order to develop a psychology or an ethics. There are psychological consequences to thinking about humans in the way Heidegger thinks about Dasein, but the consequences are beside the point. There is nothing one could say about human psychology, consciousness, neurology, behavior, historical development, or biological constitution, which would, one way or another, change what Heidegger said about "authenticity". This was not true of Sartre's ontology or of Marx's notion about human freedom. Thus when Chris Doss gives us the psychological examples that Carrol points to I think he is avoiding the primary "question of being" that matters most to Heidegger. In short "real world" examples mattered to Marx. They didn't to Heidegger, though this in-itself should not be taken as criticism.
Heidegger's idea about "authenticity" is about Dasein's relation to itself and to "being-in-the-world" -- keeping in mind Heidegger's unique definition of "world" as being something like the horizon created by Dasein. This is why in one of my previous posts I noted the Romantic reach toward authenticity in poets such as Wordsworth. In Wordsworth's terms, authenticity was a relation of an artist to himself, the integrity of his art, and the strength to create himself as a kind of work of art, through his art. This is closer to Heidegger's ideal than anything in Marx. There is no way for one person to judge another person's authenticity except possibly in the negative. If you will notice Chris Doss's "everyday" examples are all examples of "inauthenticity," not of authenticity. This brings up following question: What positive value does the ontological notion of authenticity actually have?
Keeping the above in mind one can see why Miles Jackson's criticism is particularly off-base. I am sympathetic with Miles's demand that the advocates for Heidegger show the practical consequences and applications of Heidegger's ontological authenticity. But to ask the following questions "So lack of Erschlossenheit is--practically speaking--a term of opprobrium for people who interpret their life situation in ways that seem implausible and/or inappropriate to you? The ethnocentrism and presentism of this is just breathtaking to me: should we define an Azande tribesman as "inauthentic" because he makes confident predictions about the future based on chicken entrails?" does not do justice to Heidegger. It is possible that the Azande tribesman is "authentic" in relation to Dasein and to being-in-the-world even when he is using chicken entrails as predicates for the future. In Heideggerian terms, it is possible that in the particular context of Azande pastoral life and with their animist religion an Azande individual creates a relation of self to the "world" that is "truer" in regards to "being-towards-death" (as one example) than modern humans with all of their technological meditations. In fact, I am quite sure that Heidegger would say that it was more likely for a person living in such a "pastoral society" to reach toward such an authentic relation than a person living in a "technological society." This is not because of the "social structure" of any particular society or the "knowledge" possessed by any particular individual. Authenticity in Heidegger's terms is not "knowledge". For Heidegger what we call "knowledge" in our "world" is simply another example of the evil of "productionist metaphysics." If the Azande tribesman's relation to the chicken entrails avoids the productionist evil then he may be open to an authentic relation to "being-in-the-world."
I trust I make myself obscure.
In the end I think it can be shown that Heidegger's concept of Authenticity is a circular and incoherent notion that is simply a feeling or attitude about the self, less coherent and profound than what one can intuit from reading my favorite Romantic poets. I would argue that Heidegger is simply "ontologizing" the romantic poets, which is a very un-Heideggerian thing to do, since Heidegger himself argues, convincingly I think, that a work of art is a human experience that cannot be reduced, extracted or abstracted. (Again, I am stripping Heidegger of his ontology and using the term "experience," a term which Heidegger would not use.)
Jerry Monaco