Groups defined by beliefs love their memorable catchphrases, which function as quick summaries of their groupthink. The inevitable downside—or upside, depending on the speaker's mischievousness—is irritating an outsider who tries to have a straightforward conversation. They're understandably frustrated by repetitive replies composed out of trite proverbs and smug slogans.
One catchphrase among many is "Let God be God." Generally speaking, it's a reminder of the overall attitude and conduct demanded by the speaker's god: submission. In context, it could mean "Stop being afraid or anxious about risks, because our god is omnipotent and caring." (And don't think about the countless times when it plainly permitted the worst.) Or "Stop making moral decisions through your own conscience, because our age-old teachings are superior." (And don't think about the dilemmas or concerns that aren't addressed.) Or "Stop wondering whether our god merits or craves your unending adoration, because it's responsible for making a nurturing planet and filling it with life." (And don't think about Earth's mass extinctions or the vast unlivable bulk of the universe.) Or "Stop obsessing over natural explanations for mystifying phenomena, because our god's ways exceed human comprehension." (And don't think about the historical trend of abandoning supernatural theories time after time.)
If that catchphrase has a counterpart in the stance of materialistic naturalism, then perhaps one candidate is "Let causality be causality." Metaphysical quibbles aside, here causality shall refer to the relationship between physical states of materials at differing times. Causality is the well-justified inference that a material state at later time Y is the way it is due to a related material state at earlier time X. Furthermore, due to the unique details of the state at time X, the state at time Y is not like many other hypothetical alternatives. Those would have required other hypothetical alternatives at time X. Causality is the pattern of tight sequential connection between distinct physical states, from predecessors to successors.
Surprisingly, this minimal proposition has competition. To start with, some may state, "Stuff just happens." Some may say with slightly less fatalism, "Irresistible nonphysical beings keep everything running normally moment by moment." Some may say with more optimism, "The universe is perpetually 'nudged' toward a grand purpose by a trustworthy overseer." Some may opt for the vaguer, "The universe was/is destined somehow to accomplish prearranged outcomes in my life that I call 'Fate'."
On the other hand, they may sprinkle in some science with, "Evolution deliberately molded life into pinnacles of elaborate, intelligent, self-aware creatures." The problem, of course, is that natural selection doesn't work like that. It's emphatically not separate from causality. It doesn't engineer with foresight. It's not a sculptor who gazes at a featureless stone block, envisions the final statue, then chips away the rest. The evolved organisms are the ones which more effectively survived and reproduced. Opinions about the progress of evolution are superimposed on the accretion of adaptations...and exaptations.
By contrast, when someone lets causality be causality, they "permit" current physical realities to be effects of past physical causes. Rather than symbols or clues about something else altogether, realities simply are. The present is what it is because the past was what it was. Realities don't arrive in prepackaged categories such as punishments, rewards, trade-offs, messages, omens, flukes. Although humans compulsively frame their interpretation of events with narratives of widely varying credibility, the events themselves aren't caused by human narratives. How could they, considering that the human narratives often aren't contrived until long after the unanticipated events?
Therefore, when someone lets causality be causality, they stop futilely dictating that events always conform to the preconceptions of their narratives. While things can be expected to be effects of causes, things cannot be expected to always "make sense" in every human narrative. Mere human objections don't overrule caused realities. Clearly this acknowledgment is both scary and freeing if taken seriously. The scary part is affirming that realities are untamed by narratives. The freeing part is no longer feeling obligated to fixate attention or feelings on the inevitable discrepancy between discovered realities and the narrative that was computed beforehand. (Some readers may notice a resemblance to the Buddhist technique of experiencing the present moment without prejudice.)
But completely disregarding the discrepancy is an unreasonable waste. It can furnish expensively acquired feedback for refining the mistaken narrative. By definition, a narrative is more accurate if it needs fewer feedback changes. Regardless, a permanently unchanging narrative is paradoxically suspect. Perhaps it never changes purely as a matter of policy, in which it praises its own flawlessness and forbids refinement of itself. The obvious defect is that it could be deceptively self-serving. When it indiscriminately deflects the smallest hint of faults, the narrative could in fact be faulty, for nobody can check!
However, to let causality be causality isn't to totally abandon all narratives. Not all narratives are in conflict with it. To the contrary, a narrative could implicitly embrace and reinforce it. For instance, according to a central narrative of materialistic naturalism, realities have essentially unified substances and behaviors. And the underlying unity accounts for causality. Since things are enough alike, things are able to constantly cause changes in one another. Unbroken unity is linked to unbroken causality—hereafter named unity/causality. The mass of solid Thing 1 isn't essentially dissimilar from the mass of solid Thing 2, so the gravity of Thing 1 partially causes the motion of Thing 2. After a collision, solid Thing 1 could cause solid Thing 2 to crumple, not pass through like a ghost in a fictional narrative (or a neutrino's probable journey?).
Forces come from interactions between things. In this aspect, to let causality be causality is to realize that things act as interacting components of whole "physical systems". Causality itself is the relentlessly successful proof of this truism. (Some readers may notice a resemblance to the Buddhist concept "dependent arising".) Contrary to common criticism, unity/causality isn't the absolute repudiation of "something larger than oneself". Instead, the Larger Something is more complicated, turbulent, subtle, diffuse, and impersonal than the typical proposals.
That Larger Something is admittedly abstract and the full description employs baffling mathematical formulas. Yet unity/causality also has palpable ramifications at the normal scale of human thought. At that scale, for a variety of useful purposes, humans customarily draw mental boundaries between things based on noteworthy characteristics. Nevertheless, unity/causality often violates these familiar boundaries. Fittingly, the most personal boundary it violates is the boundary around the human person, i.e. the self who observes and explains. The substance and behaviors which constitute the self are neither isolated nor special; the self is one of the earlier mentioned components of the Larger Something held together by unity/causality. For example, the self cannot create new quantities of energy—it must scavenge replacement energy from outside itself. And objects, such as Thing 1 and Thing 2 from earlier, routinely cause changes to it.
Few would reject that. Assuming they have managed to live long enough, everyone knows firsthand that their selves aren't royally privileged to override unity/causality. If they were, then the portion called the "body" wouldn't be damaged so frequently by involuntary external causes. Everyone should quickly admit that they can't face realities from an untouchable vantage point. Still, applying unity/causality to the self with unblinking consistency goes beyond that admission. To most consistently let causality be causality is to assert that the entire self is thoroughly intertwined with it, top to bottom, inside and outside.
Again, anyone who's encountered diverse personal perspectives and backgrounds could probably agree that everybody's mindsets have been demonstrably shaped, trained, caused. But they may be slower to agree that all events "of" or "inside" the self are regular albeit complex fragile specimens of unity/causality. The self's thoughts change because everything changes. The self's temper fluctuates because everything fluctuates. The self is influenced by past experiences because everything is influenced by past impacts with surrounding things. In short, the self is a highly unusual assemblage, but it isn't an exception to unity/causality. (Some readers may notice a resemblance to the Buddhist concept "no-self".)
Unfortunately, this self-portrait could appear, well, dispiriting. If someone is the effect of causes which they cannot command, then aren't they under constant coercion? Isn't it better for them to ignore this deduction and choose to believe otherwise? No, it isn't. Belief in general shouldn't be "chosen". Honest beliefs should result from candid judgments based on known findings and logical coherency, not based on willful denial. Just insisting that something is inaccurate doesn't transform its testable degree of accuracy. Wishing for the self to not be linked to unity/causality is akin to coping with unpleasant situations by shutting one's eyes.
The sensible approach is almost the opposite: to closely examine the numerous causes which sway the self. With eyes wide open, someone may realistically trace a motive or habit. Then they may grasp both the "message" behind it and that message's amount of irrationality (feeling an irrational motive is alright but mindlessly complying with it could be disastrous!). If a driver wants to avoid repeating a blowout in the future, why shouldn't they confess that the road could be having effects on their tires? Why should they continue to think that their tires are invincible? "I say that my tires are unaffected by this road, so I can drive here every afternoon without worry. All these recurring spontaneous blowouts are an irritating coincidence, though."
Gathering lots of authentic information about causes is prudent. It's an indispensable prelude to savvy active participation in unity/causality. Everyone isn't converted into a powerless spectator. To let causality be causality is to appreciate that despite each thing absorbing a multitude of effects, it nonetheless emits a multitude of causes too. If Thing 1 causes Thing 2 to fall, then Thing 2 might in turn cause Thing 3 to flatten. Human intelligent awareness enables a far more intriguing case. Humans can (imperfectly) compute wide ranges of options and the effects of those options. Moreover, they can (imperfectly) decode the causes which are manipulating them and everything around them. Finally, they can decide the causes they shall enact in order to yield the effects they want.
Unity/causality doesn't force humans to be victims only. It reflects the consequences of their actions. It can be selectively "bent" to do what they want. Its nonnegotiable condition is that it will operate in accordance with its usual rules, so productively bending it requires detailed understanding and obedience of its intricacies. A product chemical won't be the effect unless the chemist has the skill, and the reactant chemicals, and the measurement/collection/containment instruments, and the chemist carries out the appropriate steps by moving their body—whether they perform the labor or activate it in an automated form or tell a postdoc to do it. A member of a society may recognize and contemplate their society's myriad effects on them, then decide to not propagate one or more onto anyone else. Addicts can identify and avoid old "triggers" that cause the self to relapse; in particular they can decide to revise their routines and/or replace their hobbies.
That said, the potential to collaborate with unity/causality certainly has firm limits. In the end, to let causality be causality is to discern that simulations of the Larger Something aren't always feasible. Ideally, humans can make an accurate analysis by separating, sampling, simplifying, and modeling the relevant data of sections of the Larger Something. Sometimes in practice, the minimum data for an accurate analysis is too extensive. Perhaps a section cannot be analyzed independently. Perhaps a section itself contains a multitude of variant components, and the individual variances are too important for an "average" to substitute for each. In the worst case, the upshot is that a high fidelity simulation would need to include almost identical representations of almost every detail of the source reality.
The source reality's tiny causes could be amplified by working together. Then the cumulative effects abruptly cross resistant thresholds and "cascade" across the system by abruptly crossing farther resistant thresholds as well. Thus the simulation's projection could fail spectacularly...if it excluded the one tiny bit that was amplified and pivotal in retrospect. Unity/causality isn't constrained by quaint human preferences for tidy, neatly divisible factors. It's not fine-tuned to facilitate a smooth route to comprehensive knowledge or instant solutions. To let causality be causality is to confront and adjust realities on their terms.