 notion [la notion] of space. They consider that many things exist at once and they observe in them a certain order of co-existence, according to which the relation of one thing to another is more or less simple. It's their situation or distance. When it happens that one of those co-existent things changes its relation to a multitude of others, which do not change their relation among themselves; and that another new thing acquires the same relation to the others, as the former had, this change we call a motion in that body wherein is the immediate cause of the change. And though many, or even all, the co-existent things should change according to certain known rules of direction and swiftness, yet one may always determine the relation of situation, which every co-existent acquires with respect to every other co-existent; and even that relation which any other co-existent would have to this, or which this would have to any other, if it had not changed, or if it had changed any other way. And supposing, or feigning, that among those co-existents there is a sufficient number of them which have undergone no change, then we may say, that those which have such a relation to those fixed existents, as others had to them before, now have the same place which those others had. And that which comprehends all those places, is called space. Which shows, that in order to have the idea of place, and consequently of space, it suffices to consider these relations and the rules of their changes, without needing to form an absolute reality [réalité absolue] out of the things whose situation we consider.”
8. One of Leibniz's points seems to be that his relationalism is perfectly compatible with the contention that the representation of space is empirical (for the view that some of the arguments in the Metaphysical Exposition are intended to undermine Leibnizian relationalism, see Guyer 1987, 349; Wojtowicz 1997, 79, 84, 87; Brandt 1997, 96-7; Walker 1978, 42-4; Parsons 1992, 68). He apparently employs this tactic to show that perceivers can obtain a representation of space via the perception of spatial relations among objects without recourse to the view that space is ontologically independent of objects. This parallels Locke's attempt to show that one can obtain an Idea of space while having distinct ideas of space and of body. So the idea—popular among Newton's supporters like Locke—that the representation of space is empirical in origin is perfectly compatible with relationalism. Indeed, Locke's view may very well have been on Leibniz's mind when he argued for the compatibility of an empiricist conception of the representation of space with his relationalist conception of space's ontological status because of his considerable interest in Locke's theory of ideas. This is a clever tactic on Leibniz's part: when writing to Newton's most prominent defender in England, Samuel Clarke, he accepts an empiricist view of the representation of space in order to show that this acceptance does nothing to upset his defense of the relationalist conception of space's ontological status.
9. For differing accounts of this issue, see, for instance, Parsons 1992, 68 and Collins 1999, 68-9, 191 note 9.
10. On this point, see especially Leibniz's letter to Arnauld of 30 April 1687 in Leibniz 1890, 2: 101. See also New Essays, 110 and L5: 32. For an illuminating discussion of reification, see Cassirer 1902, 247, 254.
11. See “Vienna Logic,” Ak 24: 910-913 and “Jäsche Logic,” §§7-9, Ak 9: 95-98 and Ak 9: 40.
12. Of course, a Leibnizian would deny this point, and it is unclear that Kant has any argument against an alternate view—this may represent a bedrock disagreement. For discussion, see Friedman 1992, 62-8 and Posy 2000, 161-2.
13. See the so-called Physical Monadology at Ak 1: 479ff; for a discussion of this aspect of Kant's pre-critical views, see Friedman 1992, 7-9.
14. For a distinct interpretation, one according to which this may not be possible after all, see Buroker 1981, 8-9, 22.
15. On this point, see especially the “Amphiboly of the Pure Concepts 