What Lawson gets at with "openness" being all that possible ways in which a thing can be perceived reminds me of the quantum cosmological idea that reality is inherently probabilistic, and that all the different "options" available in a wave function never truly collapse, but collapse for each reference point in potentially different ways.

But where there's a difference is the idea that we're "always infinitely distant from the true open nature of things." The thought school of quantum mechanics that I'm thinking of suggests that there is NO "God-eye-view" of reality, and thus every reference frame is equally legitimate, since no one or no thing can experience multiple reference points simultaneously.

So when Lawson says that reality is a bunch of homogenous stuff that only appears to have differentiation when we using a closing tool like language, that's not far off from what quantum theorists have to say about reference frames and observation (or interaction).

Edit: a word