Chapter Six of Spinoza's Theologico-Political Treatise is entitled, "Of Miracles." We do well to see what we can learn from it. Spinoza makes four main points in this chapter, but I will examine only two of them in this entry.
We learned from yesterday's discussion of Augustine that there is a certain tension between the will of God and the existence of miracles ontically construed. Miracles so construed violate, contravene, suspend, or otherwise upset the laws of nature. But the laws of nature are ordained by God, and that would seem to be the case however laws are understood, whether as regularities or as relations of universals or whatever. So it seems as if the theist is under a certain amount of conceptual pressure to adopt an epistemic theory of miracles. We heard Augustine say, Portentum ergo fit non contra naturam, sed contra quam est nota natura: A portent, therefore, happens not contrary to nature, but contrary to what we know as nature. We find a similar view in Spinoza, despite the very considerable differences between the two thinkers:
. . . the universal laws of nature are decrees of God following from the necessity and perfection of the Divine nature. Hence, any event happening in nature which contravened nature's universal laws, would necessarily also contravene the Divine decree, nature, and understanding; or if anyone asserted that God acted in contravention to the laws of nature, he, ipso facto, would be compelled to assert that God acted against His own nature — an evident absurdity. (tr. Elwes, Dover, p. 83)
It follows from this that miracles are to be construed epistemically:
Further, as nothing happens in nature which does not follow from her laws, and as her laws embrace everything conceived by the Divine intellect, and lastly, as nature preserves a fixed and immutable order; it most clearly follows that miracles are only intelligible as in relation to human opinions, and merely mean events of which the natural cause cannot be explained by a reference to any ordinary occurrence, either by us, or at any rate, by the writer and narrator of the miracle. (p. 84, emphasis added)
In sum, since the course of nature, being ordained by God, cannot be contravened, miracles ontically construed are impossible. Talk of miracles, therefore, is simply talk of events we cannot explain. Miracles are thus parasitic upon our ignorance. They are natural events that simply surpass our limited human comprehension. To a perfect understanding nothing would appear miraculous. That is the first main point that Spinoza makes in his chapter "Of Miracles."
The second main point is that neither God's nature, nor his existence, nor his providence can be known from miracles, but can be known only from the fixed and immutable order of nature.
Spinoza's argument, expressed in my own way, is something like the following. If we take miracles ontically, as actual interruptions or contraventions of the order of nature, and thus of the will of God, then not only are they impossible, but they can provide no basis for knowledge of God. If, on the other hand, we take miracles epistemically, as events the causes of which we do not understand, then in this case as well we have no basis for knowledge of God. For we cannot base knowledge of God on ignorance, and events are miraculous only due to our ignorance of their natural causes.
Spinoza concludes his defense of his second main point with the surprising claim that belief in miracles leads to atheism:
If, therefore, anything should come to pass in nature which does not follow from her laws, it would also be in contravention to the order which which God has established in nature for ever through universal natural laws; it would, therefore, be in contravention to God's nature and laws, and, consequently, belief in it would throw doubt upon everything, and lead to Atheism. (p. 87)