In 1980 Peter Unger formulated what he called "The Problem of the Many." It led Unger to propose that nothing exists and that even he did not exist, a position known as nihilism.

Today this is the metaphysical problem of material composition and of vagueness.

let us start by considering certain cases of ordinary clouds, clouds like those we sometimes seem to see in the sky.

As often viewed by us from here on the ground, sometimes puffy ‘‘picture-postcard’’ clouds give the appearance of having a nice enough boundary, each white entity sharply surrounded by blue sky. (In marked contrast, there are other times when it’s a wonder that we don’t simply speak singularly of ‘‘the cloud in the sky’’, where each visible cloudy region runs so messily together with many other cloudy ‘‘parts of the sky’’.) But upon closer scrutiny, as may happen sometimes when you’re in an airplane, even the puffiest, cleanest clouds don’t seem to be so nicely bounded. And this closer look seems a more revealing one. For, as science seems clearly to say, our clouds are almost wholly composed of tiny water droplets, and the dispersion of these droplets, in the sky or the atmosphere, is always, in fact, a gradual matter. With pretty much any route out of even a comparatively clean cloud’s center, there is no stark stopping place to be encountered. Rather, anywhere near anything presumed a boundary, there’s only a gradual decrease in the density of droplets fit, more or less, to be constituents of a cloud that’s there.

With that being so, we might see that there are enormously many complexes of droplets, each as fit as any other for being a constituted cloud. Each of the many will be a cloud, we must suppose, if there are even as many as just one constituted cloud where, at first, it surely seemed there was exactly one. For example, consider the two candidates I’ll now describe. Except for two ‘‘widely opposing’’ droplets, one on one side of two overlapping cloudy complexes, way over on the left, say, and another way over on the right, two candidate clouds may wholly overlap each other, so far as droplets goes. The cited droplet that’s on the left is a constituent of just one of the two candidates, not a component of the other; and the one on the right is a component of the other candidate, not the one first mentioned. So each of these two candidate clouds has exactly the same number of constituent droplets. And each might have exactly the same mass, and volume, as the other.

(Mental Problems of the Many. Oxford Studies in Metaphysics, 23, Chapter 8. p.197.

In his 1990 book Material Beings, Peter van Inwagen said Unger's original insight that there are many ways to compose a cloud from innumerable water droplets should be called "mereological universalism".

Van Inwagen denies there is any way for simples to compose anything other than themselves, which van Inwagen calls "mereological nihilism."

"In the terms of our dominant Scientiphical Metaphysic, it's hard to think of myself as an entity that engages in activity he himself chooses from available alternatives for his action."

"Rather than discussing a form of Incompatibilism discussed for centuries, I'm now trying to introduce for discussion new forms of Incompatibilism."

Compare Peter Van Inwagen's Jane

Let's return to consider our Scientiphical Jane. Composed of very many Particles, and nothing else metaphysically basic, all Jane's powers must derive, in such a straightforwardly physical fashion, from the basic propensities of her quite simple physical constituents.

With less departure from Scientiphical Metaphysics, here's a second sketchy suggestion: Each of us may be a complex constituted of simpler physical entities, and each may have many Scientiphically Respectable derivative powers; but, unlike many more boring physical complexes, we'll also have radically emergent mental powers, powers with no Scientiphically Respectable derivation. Salient among these radical powers, there is our power to choose what to do from among actually available alternatives for ourselves, and, in particular, our power to choose what to think about.

On this view, it's a misleading simplification to say, with no amplification, that we're physical complexes. For, we may be mental beings just as much as we're complex physical entities. Among our very most central and peculiar powers, there'll be mental powers that have no Scientiphically Respectable derivation from any, or all, of our physical features. To avoid misleading, maybe we should say we're physical-and-mental complex beings: As with mere rocks, we have physical powers that don't (Respectably) derive from anything mental and, more peculiarly, we have mental powers that don't (Respectably) derive from anything physical.

Let's imagine ourselves as Cartesian beings who may choose, fully and freely, to move our bodies in certain ways-to wiggle our Blue thumbs, for example. So, our imaginative thought runs, we're nonphysical radically emergent mental entities that, at least from time to time, influence the course of physical reality. Now, this thought conflicts with a proposition that's accepted by almost all philosophers who, in recent decades, have written prominently on central questions of mind and body. Often going under the name "the causal closure of the physical," it's the proposition that, insofar as anything determines the course of (events in) physical reality, it's always only some sort of purely physical things that do so-some wholly physical events, perhaps.

Nothing non-physical is required, only non-material

But, if we Cartesian beings succeed in wiggling our thumbs, perhaps because we choose to move our bodies in that way, then there'll be some nonphysical things-we Cartesian beings-determining some of the course of physical reality. So, then there'll be the failure of the (so-called) causal closure of the physical. And, perhaps less poignantly, there's this same consequence should we suppose ourselves to be physical-and-mental complex beings, with an emergent mental power to choose bodily movements.

there's an effect on physical reality that's brought about through the effective exercise of a mental power of mine, not Respectably derived from features of physical reality.

Is an Exemption from Natural Law Required for Full Choice? for a being to have full choice, she must not be wholly subject to these laws; there must be at least some respects in which, at least to some degree, she is exempt from the natural laws...The laws must leave some things open to her; maybe it's left open to her to choose to increase the chance that she'll experience orange, or maybe to choose to decrease the chance she'll think that yellow is quite like orange; anyhow, there must be some powers she has that aren't wholly lawful propensities, or else she won't have a power of full choice.

As anticipated, I've not been able to make a very strong case for any Scientiphical Incompatibilism, not nearly as strong, anyway, as the case for thinking full choice incompatible with Inevitabilism, or Determinism. Why? Well, with this attempt at disclosing Scientiphical Incompatibilisms, we don't yet have much of an idea as to what it is about, say, one's having all her powers be propensities for mutual interaction, that should have full choice be ruled out for one should all one's powers be just such powers.

For future philosophical exploration, then, these avenues all but present themselves: First, and on the one hand, some should explore the possibility that, though there's an apparent clash between Scientiphical statements and our belief in our full choice, there isn't a real incompatibility here. Those wanting to uphold the Scientiphical Metaphysic should explore this avenue most energetically.

Second, and on the other hand, some might explore how we might fill the void of understanding lately remarked, so that we might come to see what it is about our Scientiphical suppositions, and what it is about full choice, that means a conflict between the two.

Third, and finally for now, there should be attempts to develop metaphysical alternatives to the Scientiphical Metaphysic, worldviews that may be more conducive to our having full choice. Perhaps, we should begin this work by energetically exploring philosophical alternatives that mean only a pretty modest departure from Scientiphicalism, our currently dominant metaphysical conception.

A view much like that just sketched may be offered in the final chapter of Timothy O'Connor's fine new book, Persons and Causes, Oxford University Press, 2000.

"Free Will and Scientiphicalism", Philosophy and Phenomenological Research, vol. 65(1), 1-24. (2002)