To quote myself, with a few modifications:
If intention is something located entirely in the writer's head then knowing an author's intention is very difficult if not impossible. Meyer's argument, derived from Lonergan, is that intention is not located entirely in the writer's head. If writing is ordinarily a communicative act then we can in principle determine what the writer intended to communicate. This is no different in principle from what we do when we read an email or talk to a friend: one communicates, the other seeks to understand what is being communicated. Now, of course, one must attend to the qualifier "in principle." There are all sort of things that can lead us to misconstrue the writer's intention. The writer might not have adequately communicated her or his intention. We might not have the requisite capacity for understanding the intention. But ultimately that is all that Meyer means by "intention": what the writer meant to communicate. He will give this "intended sense" primacy (his word), but that I think must be understood in a strictly temporal sense: i.e. reading for intention is the first thing for which a reader should aim, but not necessarily the final thing.Thus endeth what I wrote on FB. I will add the following.
Let us consider a thought experiment, in which you argue that intention, as defined above, is impossible to know. If that were the case you would not be able to know how intention is defined above. You would not even be able to know that I aimed to communicate about intention above. But if you cannot know how intention is defined above then you could not argue that intention, as defined above, is impossible to know. In short, the moment that you respond to my argument you implicitly concede the very thing against which you argue explicitly. On the supposition that no one would proceed in such a self-reversing fashion I presume that this thought experiment can remain entirely in the realm of hypothesis.