Peter,
> I am now starting to understand your privative model, thank you for
> the explanation. Presumably you would say that an English simple
> present is unmarked. So, consider:
>
> 1. This morning I read the newspaper.
> 2. Every morning I read the newspaper.
> 3. *This morning I write a letter to my mother.
> 4. Every morning I write a letter to my mother.
>
> Why is 3 not permissible (except perhaps in a rather special discourse
> context), whereas 1 is OK? Because there is an alternative form:
>
> 5. This morning I wrote a letter to my mother.
>
> But how does your model account for this difference in behaviour
> between "read" and "write"?
The above examples assume that "read" is the same word in both
sentences, but it's not. In spoken language the former is
pronounced "red" and the latter "reed," as you know. The
"alternate form" for "read" is present, it's just not represented as
such in the written script. Hence, in the "real" language there is no
difference in behavior.