It has been said that science marches to ever increasing levels of "endogeneity".
To help illustrate the concept of endogeneity consider a classic example of economic growth: the Solow Model (1956). In that model Solow posited that production (call that Y) resulted from capital (machines or different technologies) and labor. Then, there was a broad catch-all term for technology (call that A) that shifted the level of production.
So production was a function of capital (K), labor (L) , and technology: Y=f(K,L,A)
But, within Solow's model growth comes from an "exogenous" increase in A. He never explains the mechanism by which A increases only that growth comes from increases in A. In this sense, growth is like manna from heaven.
Since then other scholars have sought to explain the mechanisms that could increase A. For example, Robert Lucas provided an explanation rooted in human capital or skill formation. Human actors make decisions about whether to spend time acquiring an education. Or human actors acquire skills and "learn by doing" on the job. Both kinds of human capital enhanced productivity and therefore growth.
Paul Romer provided a related but different explanation based on the stock of knowledge in an economy. He added another sector to the economy that engaged in R&D. This sector provided new inventions that increased the stock of knowledge and that stock of knowledge generated growth. This story is a kind of "If I have seen further it only by standing on the shoulders of giants" type argument.
Now we must delve deeper into the micro foundations because we must explain the mechanism by which education, "learning by doing", or innovation happens. Economists in labor economics and industrial organization are working on enhancing our understanding of these processes. However, there will always be unanswered questions. In attempting to explain the mechanism through which each smaller detail happens we will find ourselves ever deeper into the rabbit hole. As we peel back the layers we will come to the original question of existence itself.
I think we will find that that not everything that exists can be caused by something else that exists within the system. This is the argument from efficient causality that is expressed well by Peter Kreeft (block quote taken from Strange Notions):
*Addition: I did not note that there is also an argument here for the existence of God from the standpoint of intelligibility. Science presumes that there is intelligibility in the world, i.e., the objects under investigation are knowable and can be understood. If scientists did not believe the world was intelligible there would be no reason to launch investigations. The pervasiveness of this intelligence in the world implies the existence of an intelligent designer.We notice that some things cause other things to be (to begin to be, to continue to be, or both). For example, a man playing the piano is causing the music that we hear. If he stops, so does the music.Now ask yourself: Are all things caused to exist by other things right now? Suppose they are. That is, suppose there is no Uncaused Being, no God. Then nothing could exist right now. For remember, on the no-God hypothesis, all things need a present cause outside of themselves in order to exist. So right now, all things, including all those things which are causing things to be, need a cause. They can give being only so long as they are given being. Everything that exists, therefore, on this hypothesis, stands in need of being caused to exist.But caused by what? Beyond everything that is, there can only be nothing. But that is absurd: all of reality dependent—but dependent on nothing! The hypothesis that all being is caused, that there is no Uncaused Being, is absurd. So there must be something uncaused, something on which all things that need an efficient cause of being are dependent.Existence is like a gift given from cause to effect. If there is no one who has the gift, the gift cannot be passed down the chain of receivers, however long or short the chain may be. If everyone has to borrow a certain book, but no one actually has it, then no one will ever get it. If there is no God who has existence by his own eternal nature, then the gift of existence cannot be passed down the chain of creatures and we can never get it. But we do get it; we exist. Therefore there must exist a God: an Uncaused Being who does not have to receive existence like us—and like every other link in the chain of receivers.Question 1: Why do we need an uncaused cause? Why could there not simply be an endless series of things mutually keeping each other in being?Reply: This is an attractive hypothesis. Think of a single drunk. He could probably not stand up alone. But a group of drunks, all of them mutually supporting each other, might stand. They might even make their way along the street. But notice: Given so many drunks, and given the steady ground beneath them, we can understand how their stumblings might cancel each other out, and how the group of them could remain (relatively) upright. We could not understand their remaining upright if the ground did not support them—if, for example, they were all suspended several feet above it. And of course, if there were no actual drunks, there would be nothing to understand.This brings us to our argument. Things have got to exist in order to be mutually dependent; they cannot depend upon each other for their entire being, for then they would have to be, simultaneously, cause and effect of each other. A causes B, B causes C, and C causes A. That is absurd. The argument is trying to show why a world of caused causes can be given—or can be there—at all. And it simply points out: If this thing can exist only because something else is giving it existence, then there must exist something whose being is not a gift. Otherwise everything would need at the same time to be given being, but nothing (in addition to "everything") could exist to give it. And that means nothing would actually be.Question 2: Why not have an endless series of caused causes stretching backward into the past? Then everything would be made actual and would actually be—even though their causes might no longer exist.Reply: First, if the kalam argument (argument 6) is right, there could not exist an endless series of causes stretching backward into the past. But suppose that such a series could exist. The argument is not concerned about the past, and would work whether the past is finite or infinite. It is concerned with what exists right now.Even as you read this, you are dependent on other things; you could not, right now, exist without them. Suppose there are seven such things. If these seven things did not exist, neither would you. Now suppose that all seven of them depend for their existence right now on still other things. Without these, the seven you now depend on would not exist—and neither would you. Imagine that the entire universe consists of you and the seven sustaining you. If there is nothing besides that universe of changing, dependent things, then the universe—and you as part of it—could not be. For everything that is would right now need to be given being but there would be nothing capable of giving it. And yet you are and it is. So there must in that case exist something besides the universe of dependent things—something not dependent as they are.And if it must exist in that case, it must exist in this one. In our world there are surely more than seven things that need, right now, to be given being. But that need is not diminished by there being more than seven. As we imagine more and more of them—even an infinite number, if that were possible—we are simply expanding the set of beings that stand in need. And this need—for being, for existence—cannot be met from within the imagined set. But obviously it has been met, since contingent beings exist. Therefore there is a source of being on which our material universe right now depends