Moderation in metaphysics seems key. A great passage from an article which I'll link below: "Hartshorne, Metaphysics, and the Law of Moderation" by Dan Dombrowski.
From this insight, however, defenders of external relations like Russell show no more hesitation than Leibnizians regarding the acceptance of symmetrical relations. If events in nature are mutually independent, then nature is analogous to a chaos of mutually independent propositions (CSPM 83). The defender of asymmetry (who views a present person as internally related to his past but as externally related to his future) finds it comical to see Russell attacking rationalists like Bradley and Hegel because they had little or no use for anything but internal relations. And it is equally comical to see partisans of purely internal relations like Bradley or Blanshard trying to refute Hume, James, or Russell (CSPM 96).
One defect in the theory of purely external relations is that we do in fact usually talk as though events depend on what happens before but not on what happens afterwards; we do talk as though asymmetry is the case. This in itself does not refute a Hume or a Russell, but it should lead defenders of purely external relations to wonder if believing in events as dependent both ways (i.e., present dependent on past and present dependent on future) is necessarily worse than believing in events as independent both ways (CSPM 147, 213). There is also the familiar difficulty of preserving moral responsibility for one's past actions if one is not internally related in some way to those actions.
Consider the following clever and, I think, devastating example from Hartshorne:
One may parody the prejudice of symmetry as follows: Suppose a carpenter were to insist that if hinges on one side of a door are good, hinges on both sides would be better. So he hangs a door by hinging it on both sides, and it then appears that the hinges cannot function, so that the door is not a door but a wall. "We'll fix that," says another carpenter, and removes all the hinges. So now the door is again not a door, but a board lying on the floor. This is how I see the famous controversy about internal and external relations. The first carpenter is Spinoza, Bradley, Royce, or Blanshard; the second carpenter is Hume, Russell, Von Wright, Ayer, or R. B. Perry. (CSPM 216)
More complications set in when it is realized that a symmetrical theory of purely internal relations leads, as Hegel and Bradley realized, to monism, whereas a symmetrical theory of purely external relations leads, as Russell realized, to a radical pluralism. Russell's mistake was in assuming that one had to beeither an absolute monist or an absolute pluralist and that one could not benefit from the strengths of internal and external relations (CSPM 216). Defense of purely internal relations leads to the erroneous conclusion that we can only expect what laws governing the internal relations will allow, and the view which emphasized purely external relations should lead to the conclusion that at each moment anything could conceivably happen next (LP 174). Speaking of Perry, James, and Russell, the following astute observation is made by Hartshorne:
The combination of extreme causal determinism and extreme pluralism (lack of any internal relations connecting the constituents of reality) repeated the most bizarre feature of Hume's philosophy. The combination violently connects and violently disconnects the constituents of reality. (CAP 156)