Simon Episcopius led the Remonstants at Dort, after Arminius’ death. (link for background on Episcopius) Like Arminius, he held to middle knowledge. (link) Here’s what he had to say about middle knowledge:
This order to be rightly understood, has come to be observed, by usually attributing to God threefold knowledge. One which is necessary and practical and is called simple intelligence, which by its nature is prior to all free acts of [the divine] will, which God has of himself and knows all possibilities. The other free, which is called vision, and is after the free act of the [divine] will, by which God has decreed to do or permit all things, knows the same order, when it decided to make or permit to be done. Third,
Middle, by which God knows what men or angels would do by their own freedom, under conditions, if with these or those circumstances, in this or that state, or established order. Whether this distinction is rightly said of the divine knowledge, we do not consider. But that it is convenient and that the doctrine of grace becomes possible, no one doubts. And this is why we set the second distinction, in the order of the objects of divine knowledge.
Ordo hic ut recte intelligatur, observandum venit, triplicem Deo scientiam tribui solere. Vnam, quae necessaria est, and practica atque simplicas intelligentia dicitur, quae ex natura sua omni voluntatis liberae actu prior est, qua Deus se ipsum & alia omnia possibilia intelligit. Alteram liberam, quae visionie dicitur, & actu voluntatis liberae posterior est, qua Deus omnia, quae facere aut permittere decrevit, eodem ordine novit, quo ea decrevit facere aut permittere ut fiant. Tertiam,
Mediam, qua Deus novit quid homines aut Angeli pro sua libertate facturi essent, sub conditione, si cum his aut illis circumstantiis, in hoc vel in illo statu aut ordine constituerentur. An haec divinae scientiae distinctio recte fait, nos non expendimus. Quin ea commode & doctrinae gratia fieri poffit, neutiquam dubitamus. Quare secundum hane distinctionem, hunc in objectis divinae scientiae ordinem constituimus. (Works of Simon Episcopius. Page 303)
I like his practical approach. He doesn't try to crawl behind middle knowledge to discover it’s source. Rather, he accepts middle knowledge because of its benefits.