In physics, the n-body problem might be stated — certainly with a great deal of oversimplification — as follows:

Given the initial conditions (instantaneous position, velocity, and time) of a group of n celestial bodies under gravitational forces, predict their orbital characteristics at all future times.

One would think this would be relatively straightforward given the well established laws of Newtonian, and even relativistic, mechanics. One would be wrong. There are, indeed, no exact general solutions for n>2. That is, for as few as three bodies in motion, there is no exact general solution.

A similar difficulty obtains with the traveling salesman problem (TSP):

Given a list of cities and the distances between each pair of cities, what is the shortest possible route that visits each city exactly once and returns to the origin city (Wikipedia)?

For a relatively small number of cities, a calculation of each possible path is feasible and will yield the desired result. But for n cities, where n is a “large” number? Again, there is no general solution.

I mention these two mathematical conundrums only to demonstrate that the world is exceptionally complex and that our knowledge, though vast, soon reaches it limits.

An event occurs, one which is, by general consensus, considered evil, if not morally, then at least in the sense of opposing human flourishing and scandalizing society: a school shooting, a genocide, an act of terrorism, an abuse of innocence, a predatory act of the powerful against the powerless. On a personal level, the event might be the betrayal of a vow or trust, the terminal diagnosis, the end of a relationship. And the question comes: Why? Why did this happen?

It is little comfort but absolutely true to say that any such event is an n-body problem, a TSP. There are simply too many inputs and the relationships among the “bodies” are far too complex to permit an exact solution. A teenager comes out of a recreation center, two car screech to a stop, multiple masked boys jump out of the cars and open fire killing the teenager. Why? The “simple” answer might be that this is another gang-related dispute. But that explains nothing. Why are there gangs in the neighborhood in the first place? Why were guns accessible to teenagers? What could one boy do to others that “merits” murder? Answer any of the questions and you will generate a new question, the question tree branching ad infinitum. There are thousands of inputs to the equation: thousands of individual decisions that careen this way and that, impacting or glancing off other decisions, barely missing others, until the cars’ doors open and the bullets fly. It might have been different had not countless small influences conspired to produce this tragedy. Change any one of the inputs, and the outcome might have been entirely different.

Those who seek to move the question from the cultural/sociological realm to the spiritual one typically mean something different by the question, “Why?” Why? might more nearly mean, Where was God is all this? Given what we know about the character of God as revealed in Jesus Christ, I think we can rightly say that God was in the midst of every one of those countless decisions influencing them toward the good, the Holy Spirit now encouraging, now convicting, but not overriding the will of those who chose. That is my experience, at least. God will conspire to make my sin difficult and costly, to prick my conscience before I sin, to convict me preveniently. But, if I insist, God will leave me to my decision, to my devices, and to my consequences. As much as I might say I would like a world in which God would prevent (stop) me from making a sinful choice and committing an evil action, I cannot quite convince myself that that is true. The wrong that I do, I often do knowingly and willfully. And I do not, in the moment, want to be stopped. It seems that both God and I value my freedom. I do, in my best moments, long for that day when freedom will mean freedom from the passions that make me choose sin. I do not have enough of those best moments.

So, it does no good, it seems, to ask why an evil act occurred: the moral and spiritual world is too complex for either a general or specific solution. And generally, we usually mean something different when we ask, “Why?” any way, something more akin to: Why would God allow this to happen? I have no desire to be pedantic, but I must quibble a bit with the word “allow” as used in the question. If the implication of “allow” is that God simply sat back passively and watched this evil thing happen, then I think the question is flawed. My conviction — and I think the thrust of Scripture — not least the Sermon on the Mount — is that God is always and everywhere actively engaged for the good of all creation, that is, for the redemption and restoration of this fallen world and these fallen people. But, for reasons known to himself and only to himself, God usually chooses to work with fallen people in a fallen world by divine influence and not by divine fiat. God woos us and warns us; he does not usually ravish us or prevent us. Reality is, of course, more complicated than this general principle, but it is, on the whole, true. As we see in the life of the pharaoh, God may harden hearts that have already resolutely resisted him, confirming them in their rebellion. He does raise up peoples for his use, peoples who are willing to be so used — think the Babylonians — and yet holds them accountable when they exceed his mandate. He will and does call/elect people vocationally. All of this is more than mere influence, and yet even here, the individuals and nations made and make their choices.

Blame C. S. Lewis for this post, specifically his book “Miracles.” It has me thinking again of providence and miracles and natural law. Some have a “strong” view of providence which would maintain that every event was decreed in the mind and will of God from before the foundation of the world, that all is developing as indeed it must, even my writing of this and your reading of it. But, that is not the way it seems to me. I seem to have a choice in this decision to write and, indeed, in all the “decisions” of my life; hence, the need to pray for wisdom and discernment. I’m unable to reconcile discernment with the strongest notions of providence. Presbyterians can. I am not a Presbyterian.

My concept of providence is more akin to my time teaching in a secondary mathematics classroom. I knew the ultimate outcome of each lesson and, indeed, of the whole course; these ultimate goals were planned before I ever received my class rolls for the year. I could have scripted all my classes beforehand and could have forbidden any student engagement that might disrupt them: sit still, be quiet, do the assignments. But, for the benefit of the students, I gave them the dignity of real participation. I constantly interacted with the students to prompt appropriate learning and relational engagements. I exercised discipline when necessary to address misbehavior. Granted, some things happened that I didn’t intend and didn’t desire. But, I knew that I could address those adequately and often even turn them to good; I knew that I would reach the goals I had established. The students may not have known — could not have known but for my self-revelation — exactly why everything developed in the classroom the way it did. They had to learn to trust me, to trust that I was acting always for their good. Some learned that; some doubted me. Some flourished, and some, usually by their own choices or by ten thousand choices made in the years before by themselves and others, failed. Such was my providential governing of the classroom: always engaged for the flourishing of the students while allowing them the dignity of real choice and real participation.

That is, by no means, an adequate explanation of providence and even less of why any particular event occurred. But it does, at least for me, align with the notion of a God who is always actively engaged for good, a good which includes the power — for good and ill — of human freedom.