As part of Malebranche's moral theory, he argues that it is morally necessary for God to give all creatures an impulse toward the universal good (which in Malebranche's view is God Himself).In our case, this orientation to universal good is the natural impulse of our will to happiness, which we can only find in God. Every human person, therefore, is in a constant state of search for the sort of satisfaction it can have in perfect love and knowledge of God. In this state of search, the will directs the mind’s attention this way and that. We attend to objects that seem to give us something of this satisfaction. Something like this would also have been true in Adam’s original state. We move from finite good to finite good because our minds are not infinite, and therefore cannot comprehend the whole of infinite good at once. This would also have been true of Adam; although perfect, he was as finite as we are. While no finite mind can completely comprehend infinite good as such, the mind can in principle regard each finite good in light of the infinite good from which it derives, i.e., it can consider each finite good as necessarily implying and presupposing the more fundamental universal good. For Adam, presumably, this would have been a regular occurrence: he would recognize each good to which he attended as something due to God and every pleasure he received from good objects as something caused by God. Going beyond finite good to infinite good, however, requires more than the original impulse; enjoyment of the finite good must be suspended until we have seen this limited good in light of the infinite good from which it derives (cf. LO 548; OC 3:19). This is where we go wrong; when enjoying a finite good, we stop at it and enjoy it alone rather than waiting to place it in the context of infinite good. In other words, we sin, the nature of sin being a failure to take the next step and see the creature in light of its Creator: "All we do is stop and rest" and by so doing we "frustrate the impulse God impresses in us" (LO 551; OC 3:25).
This failure to follow through on our impulse to love God as the universal good has important philosophical ramifications. In practice this disorder is an excessive concern with bodies, a concern so strong that it is dependence. It is false love: we treat bodies, rather than God, as our true good of the mind, which makes us exalt our union with bodies over our union with Order, in the process running afoul, of course, of principles of Order (principles like "bodies are not worthy of love" and "all the love that God places in us must end in Him"). Since this motion of love toward good is the will, and since the will governs attention, we are driven to attend more to sensible matters than their ethical importance and value for inquiry would merit. While the senses are not corrupt in themselves, then, our excessive dependence on them is an essential feature of the corruption of our cognitive capacities. Because it affects the way we interact with sensible goods, the disorder of original sin has serious epistemic consequences. In particular, "the mind constantly spreads itself externally; it forgets itself and Him who enlightens and penetrates it, and it lets itself be so seduced by its body and by those surrounding it that it imagines finding in them its perfection and happiness" (LO 657; OC 3:203). Our primary union is with sovereign Reason, but, distracted by our union with sensible things, we treat this latter union as if it were more important; and because "we cannot increase our union with sensible things without diminishing our union with intelligible truths" (LO 415; OC 2:257), we ignore our union with universal Reason to the extent we devote our attention to sensible things. The reason, Malebranche thinks, is that we enjoy making judgments, and therefore try to have this pleasure without first consulting Reason (cf. LO 649; OC 3:189).
This is where idolatry enters into the picture. Malebranche’s chief complaint against the senses, or, at least, the role they currently have in our cognitive lives, is ethical in inspiration: our sensory union with the body misleads us into loving lesser goods over the universal good, God, and thus makes us dependent on something to which we should be superior. This brings with it a sort of self-deception; as he notes, it is not our union with God that deceives us, nor even the union with the body itself, but our dependence on the body (LO 649; OC 3:189). We are, one might say, addicts. Much as the drug addict finds his thought, his desires, even his ability to act on his most cherished convictions, distorted by a desire for this or that chemical, so we find our thoughts, desires, and ability to act distorted by our desire for sensory pleasure in general. The difference between the two, in fact, seems merely to be one of degree. Human beings in this state of dependence on the body find themselves drawn by that dependence into idolatrous states of mind.
This idolatrous tendency is the key issue in Malebranche’s account of causation; it is why he is so insistent on occasionalism. For him, occasionalism is not merely a philosophical position. It is morally necessary. Without it, we become (at least implicitly) pagans.
Suppose we assume that bodies are true causes. What does this import into our way of looking at the world? Granting genuine power to bodies is, Malebranche claims, a way of granting them some sort of divinity: "If we next consider attentively our idea of cause or of power to act, we cannot doubt that this idea represents something divine" (LO 446; OC 2:309). Causal power, is power over things, to support or to impede them, to harm or to benefit them. One indication that there is this element of god-likeness in our idea of power can be seen in paganism, which directly regards these powers as in some way divine. Any attempt to attribute causal powers to things is an attempt to resurrect pagan superstition, or something closely parallel to it.
For Malebranche, a pagan worldview follows closely on, and is perhaps the primary consequence of, original sin. It is this recognition that mediates between his arguments against necessary connection and his general views; it is because of their ethical role, as correctives to the presumptions of the pagan mindset, that the arguments interest him. Occasionalism is an ethical antidote, or at least an ethical treatment, for our tendency to idolatry, and, in particular, for an especially pernicious instance of this idolatry:
If the nature of pagan philosophy is a chimera, if this nature is nothing, we must be advised of it, for there are many people who are mistaken with respect to it. There are more than we might think who thoughtlessly attribute to it the works of God, who busy themselves with this idol or fiction of the human mind, and who render to it the honor due only to the Divinity. (LO 668; OC 3:223-224)
What Malebranche regards as the philosophical superstition of causal powers or efficacious natures is but one more sad example of the terrible failure of human nature to live up to the demands of Order; it is but one more expression of the "secret opposition between God and man" (LO 657; OC 3:204). It is not a conclusion of Reason, but of the Devil; it is, in Henri Gouhier's excellent summation of Malebranche's view, "the philosophy of the Serpent".
It is noteworthy that Malebranche is not the only person to draw a connection between a causal powers theory of causation and paganism. Hume, both in the Enquiry Concerning Human Understanding and the Natural History of Religion, does the same; and many of the arguments against causal powers that Hume takes over almost directly from Malebranche are, in Malebranche, part of a fierce and extended attack on idolatry as a philosophical mistake.
[LO= the Lennon-Olscamp translation put out by Cambridge University Press; and OC is the Oeuvres Complètes.]