Stapp and Quantum Agents

For several decades now, physicist Henry Stapp has been publishing books and papers which develop an explanation of human consciousness grounded in quantum mechanics (an online list of Stapp’s papers from recent years is here). I just read this new article, published in the Journal of Consciousness Studies. This particular article includes a review of his general approach in layman-accessible terms, and then highlights his proposed linkage of the efficacy of conscious will to the quantum zeno effect. This is interesting stuff, and I would highly recommend that students of consciousness read Stapp. For now, I have a brief comment (which is off the main topic of the paper) on a set of long standing questions I have about Stapp’s work: if quantum effects are needed to explain the workings of the human brain, aren’t they also needed to explain other macroscopic phenomena? Is it only in the human brain where a classical approximation fails to provide a full explanation? In terms of causation, are human beings the only quantum agents?

In other words, I feel like we’re missing some steps in our description of reality. Humans, after all, evolved from lower forms of life. Life itself was bootstrapped out of the inorganic world. While human consciousness is unique in so many ways, it seems most plausible that humans leverage capabilities inherent in other natural systems, rather than utilize utterly unique mechanisms.

Stapp seems surely right when he says that certain brain processes are grounded in the quantum realm (he cites the size of ionic channels between synapses as being on a scale where quantum effects must exist). But couldn’t this be true of cellular processes outside the brain, too? How about in single-celled animals? If quantum interactions (=measurements) are the raw material of the macroscopic world (as I speculated in my recent post), shouldn’t this be in evidence in realms other than the human brain?

Here’s a comment from Stapp on this (made somewhat as an aside):

"But if one considers the Von Neumann theory to be an ontological description of what is really going on, then one must of course relax the anthropocentric bias, and allow agents of many ilks. Yet the theory entails that it would be virtually impossible to determine, empirically, whether a large system that is strongly interacting with its environment is acting as an agent or not. This means that the theory, regarded as an ontological theory, has huge uncertainties.
However, our interest here is the nature of human agents. Hence the near impossibility determining the possible existence of other kinds of agents, will mean that our lack of information about the existence of those other possible kinds of agents will have little or no impact on our understanding of ourselves."

This seems too quick of a dismissal of the ubiquity of quantum agents. For what it’s worth, here’s my alternative view of how things could work. Macroscopic systems in nature can be described in terms of systems which coordinate quantum micro-agents. The raw material of first person experience and intentionality comes from small quantum interactions, which are then leveraged through special functional networks in human brains to give rise to the familiar large scale features of consciousness. This account would be consistent with the fact that consciousness is tied intimately to the specific structures of the brain while also addressing why the deepest mysteries of consciousness (why there is first person experience and intentionality at all) are impervious to description in classical terms.

The research agenda to get at these issues would include trying to figure out whether single-celled animals might utilize quantum effects and whether quantum physics plays any role in an account of the origin of life.

Local vs. Global Possibility and the Link to Causality

Below is a post inspired by reading this paper by Georgetown’s Alexander Pruss (thanks to Tychic for the pointer to this). It has a number of interesting ideas relating to modality and causality.

Early on in this paper, Pruss makes the point that our every-day modal claims are mainly about “local” or adjacent possibilities. For example, “were I to drop this glass, it would fall”. Importantly, our intuition is to view these claims as being about possibilities local to us in this concrete world, not located in another possible world.

He then discusses the philosophical tradition of analyzing of modal statements in terms of possible worlds -- we might call this a “global” treatment of modality. Pruss concurs with the consensus on this subject that there are compelling analytic reasons to approach modality in this way. He also discusses the idea of truthmakers for modal claims, which leads to a discussion of realist accounts of possible worlds.

He spends part of the paper critiquing two main versions of “possible worlds” modal realism; the concrete version of Lewis, and the abstract versions of Plantinga and Robert M. Adams (with emphasis on Adams). One of his two main critiques of Lewis is the charge that inductive inferences about the future are invalid in this scheme (the second is an argument about ethical paradoxes). We could be in a world where gravity fails tomorrow! This point is familiar from discussions of Hume’s treatment of causation. Lewis’ overall scheme of counterfactual analysis of causation plus modal realism is self-described by him as Humean in spirit, so presumably he wouldn’t have been bothered by this criticism.

Pruss mentions a prominent criticism of abstract possible worlds, which is that what distinguishes one possible maximal state of affairs as our concrete world is unexplained – it is a primitive of the theory.

His next criticism is the important one for where he’s going in this paper: He criticizes the abstract system for the fact that all of these possible worlds already exist, prior to any seeming need for them to explain a local possibility in our concrete world. The simultaneous existence of all these abstract possibilities is a problem for Pruss, because it conflicts with the Aristotelian maxim that “actuality is prior to possibility”. And if the maxim is valid and possibility is grounded in actuality, then it means that the actuality “has some powers, capacities or dispositions capable of producing that possibility, which of course once produced would no longer be a mere possibility.”

This again ties the discussion of modality back to a discussion of causality. Abstract entities are usually viewed as categorically unable to enter into causal relations. Aristotle’s system of causation is a real causal production system which follows from the causal capabilities and dispositions of actual entities in the (concrete) world.

If what Pruss says is right and this Aristotelian view can produce possibilities, could this be the basis for a full alternative treatment of modality which obviates the need for a scheme like Lewis’ or Adams? The idea is that “a non-actual state of affairs is possible if there actually was a substance capable of initiating a causal chain…that could lead to the state of affairs we claim is possible”.

Pruss himself sees two obstacles for this approach. First, while it works for local possibilities, it’s not clear you can get global possibilities (whole possible worlds) out of it. The second problem is the initial grounding of the contingent concrete things to begin with: how did this party get started?

Finishing the paper with a theistic turn, Pruss proposes that a possible solution to these two problems would involve a necessary first cause. A possible world which is not actual would be linked to the actual by following the chain of causation backward until we found a starting point which could serve as a branching point for both worlds. This would be the first cause.

So, starting with an analysis of what makes modal claims true, we’ve taken a roundabout route to the cosmological argument for the existence of God. Whew! (In a second paper here, Pruss has offers further arguments about the Principle of Sufficient Reason, the Cosmological Argument and related topics).

There is lots of thought-provoking stuff here. The point I want to emphasize again is the linkage between solving the problems of modality and causality. David Lewis’ system for handling both topics seems rigorous and consistent, but violates our intuition that real causation and possibility are active in our concrete world. It’s unclear that abstract possible worlds can be linked to causality given the normal view of abstract objects as causally inert, so this is a weakness of this approach. Using one view of real causation, the Aristotelian one, Pruss can get to a treatment of modality, but it requires a big commitment to a necessary first cause to make it work. I'm not sure about that move, but it seems right to me that the path to a solution does does depend on working out a system of real causality.

The Duality at the Heart of Physics

I’m speaking of the measurement problem or paradox in quantum physics. One the one hand we have the continuous deterministic dynamical evolution of the wave function (in Schrödinger’s formulation of quantum mechanics), and on the other we have the discontinuous process of measurement which “collapses” the wave function into a definite state. What, if anything, does quantum physics mean for the nature of reality?

Interpretations of this problem historically have tended to devalue the ontological status of one or the other side of this duality. Some versions of the Copenhagen interpretation treated the wave function as a mere calculation framework which shouldn’t be accorded the status of something real. Over recent times, variants of the many-worlds hypothesis have become more popular: these emphasize the reality of the well-behaved wave function, and dismiss our perception of the everyday classical world as either a limited or illusory view of true reality. As I wrote in (the last part of) this post, more careful analysis of Neils Bohr’s own views tend to show he understood that the two quantum processes were irreducibly interdependent.

My own view is that quantum measurements are the events which make up the concrete fabric of our world. The wave function also exists, however, and can be considered the space of abstract possibilities which provide the raw material for the actualization of each event. While we can only observe "inter-measurement" phenomena associated with the wave function (e.g. entanglement) in carefully constructed laboratory situations, it comprehensively enters into our everyday world as well.

In fact, each larger system in nature is an extended event complex which continually self-implements measurements as interactions with the environment. Each set of measurements gives rise to a new possibility space which is raw material for further events.

Notes on Plantinga's Modal Realism

Here are some brief notes on Plantinga’s system of modal realism. I have not found this to be easy territory. Sources: Essays in the Metaphysics of Modality, and Christopher Menzels’s SEP article on Actualism.

In place of possible worlds we have a full set of abstract maximal states of affairs. These “worlds”, along with the concrete world we know, are all part of existence. The difference between an abstract maximal state of affairs and our everyday world is that ours happens to be the maximal state of affairs which “obtains” -- this obtaining is analogous to a propostion being true. Note: in some of Plantinga’s writings, he says our world is the actual world, and the abstract ones are not actual, yet they exist. It’s easy for “those of us at home” to be confused when the words ‘actual’ and ‘exists’ are divorced! But leaving this aside, it is a primitive fact that one world – ours—is picked out as the concrete world. Lewis was extremely critical of this aspect – in his system actual is a merely indexical term: the actual world is the world I happen to be in, but otherwise the worlds exist on even-handed terms relative to each other.

Another key aspect for Plantinga is that for any object/individual there exists an individual essence. This is unlike Lewis’ counterpart theory, where I have counterparts in other worlds, and there is no dogma saying precisely when it is that the counterpart’s properties differ enough from mine that it is no longer worthy of being called my counterpart. The postulate of individual essences also seems a brute primitive. It serves to replace possible individuals in modal statements with something ‘actual’. But it’s not an actual individual – it is an (platonic) essence. The notion of individual essence seems to me a way to avoid the question of what it is which makes a bundle of properties an individual. (Some technical objections to this part of the system are also summarized in Menzel’s article.)

Plantinga takes seriously that we need to have truthmakers for modal truths (which I like). He also thinks there are should be no non-existent objects or mere possibilia as truthmakers, so everything needs to be explained via things which exist. To make it work, he needs a panoply of abstract entities to cover all the angles. I don’t have a problem with this in and of itself, since I am open-minded regarding the existence of abstract objects. The 2 issues I have are those mentioned above: first, the way our world gets picked out of the set of abstract worlds is a primitive; and the postulate of individual essences (as distinct from individuals themselves) is another feature I find somewhat gratuitous.

Platonism on Tap at Maverick Philosopher

Posts on the subject are underway at Bill Vallicella's active and interesting blog (see here and here). Good group of commenters as well.

Driven to Abstraction

Plato just won’t go away.

I’ve been thinking about whether the truthmakers for modal truths could involve abstract possible worlds, but this requires backing up a bit in order to consider the status of abstract objects in general.

Defining what it is to be "abstract" is not trivial. Lewis made this point in On the Plurality of Worlds. His breakdown of several ways to approach the question is followed by Gideon Rosen in this brief SEP article on Abstract Objects. The most often used methods are to define abstract objects in terms of what they are not, and then work out the idea using examples. Abstract objects are neither physical nor mental – usually they are thought of as unchanging and causally inert (the potential role of abstract objects in a theory of causation is something to come back to, however). Numbers and universals (“redness”, “roundness”) are paradigm examples.

This SEP article on Platonism in Metaphysics, by Mark Balaguer, summarizes the state of abstract objects in modern metaphysics. He surveys the landscape by seeing how the main candidates for abstract object status (mathematical objects, properties, propositions, possible worlds) fare under Platonism and its main rivals (nominalism, immanent realism, conceptualism). It’s an exceptionally reader friendly article, and was a helpful review for me.

One item I thought was interesting is that, according to Balaguer, the strongest argument for Platonism is a truthmaker argument. The things denoted in literally true statements (“3 is prime”) must exist as abstract objects in order to make the statement true. Alternative accounts of how these statements work or attempts to deny their truth all have problems and objections.

Of course, Platonism has strong objections. Balaguer singles out the epistemological issue as the biggest problem: if abstract objects are non-physical (and exist outside of space-time) how can we have knowledge about them? Different accounts have been proposed regarding how this can work; objections have been lodged, and the debate continues.

There is a running “meta-theme” here which I’ve been thinking about as I’ve tried to survey different topics in metaphysics (ontology, causality, modality). These metaphysical questions are difficult, and simple solutions obviously don’t work or the debates would have ended long ago. What this means to me is that the common presumption that something like physicalist monism should be the “default” metaphysical position is unfounded. More “extravagant” metaphysical systems need to be weighed in the quest to find a better mousetrap for explaining how the world works.

The World is not Enough

Picking up the thread on modal metaphysics (most recent post here): If I follow Armstrong’s truth/truthmaker approach to metaphysics and I insist it apply adequately to modal truths regarding necessity and possibility, it seems to lead (contra Armstrong’s own conclusion) to a modal realism involving possible worlds. David Lewis is the leading proponent of the theory that all possible worlds exist concretely. So what are the specific strategies for those who want to avoid joining Lewis? I “hit” the Stanford Encyclopedia of Philosophy to learn more. A brief summary of two relevant articles is below (keep in mind that this stuff is new to me and I’m even more prone than usual to misreading something – please check out the source articles if you’re interested).

There are two broad options here. First, try to deny any need to appeal beyond our single actual world. Second, substitute an account of abstract entities for Lewis’ concrete ones. This latter approach I will come back to in a future post.

Christopher Menzel wrote the SEP article called “Actualism”. Actualism is the thesis that there are no non-actual individuals or worlds. The article discusses various strategies to defend this thesis. Menzel discusses modal logic, and the fact that the simplest modal logic can be made to generate theorems which are troubling to the actualist. One of them is something like this: the statement {it’s possible that a flying pig exists} implies the statement {there exists something which is possibly a flying pig}. Next, he then summarizes how Kripke and others introduced modifications to modal logic meant to prevent the derivation of these sorts of statements while preserving the ability of the logic to do its modal work. The article leads one to conclude these efforts have not met with success: there isn’t a way to have a fully robust modal logic which has an actualist metaphysics as its analogue.

The article also discusses other programs to defend actualism (“world stories"/"world propositions”) which deflate the status of troubling implied statements into something innocuously only about propositions, not individuals. According to Menzel’s account these attempts also have serious objections – mainly they don’t do justice to analyzing the role modal statements really play in our language and thought. (He also devotes a section on Plantinga’s system of abstract possible worlds; this is something I will spend more time on before commenting).

Another strategy, which Armstrong himself once advocated, is called “Modal Fictionalism” – the SEP Article on this is authored by Daniel Nolan. This is the idea that this talk of possible worlds is a useful fictional construct not meant to be taken at face value. While this sounds attractive, the strategy suffers from objections, too. These include technical objections (logical formulations of modal fictionalism can lead to contradictions or circularity). Also, modal statements have more “objectivity” than authored fictions - if they’re not actual, they would be more like “hard” abstractions (mathematics being the paradigm example). A related point is that modal fictions are incomplete since they suffer from the author’s ignorance about many modal statements. Several other objections are outlined in the article as well.

Now as I said above I’m new to all of this, and it’s possible that some strategy exists or will be developed in the future which does justice to analyzing modal language and its role in rational thought while keeping to a deflationary actualist metaphysics. All I can safely say here is that all the attempts in the literature mentioned in these articles are described as having serious outstanding objections.

Materialists Missing the Point

I want to discuss 2 strategies I see used by advocates of materialism when trying to counter the devastating objection that materialism cannot account for the existence of first-person phenomenal experience. Both of the strategies make an insightful point, but then overstate the traction of this point on the essential problem thereby showing the materialists don’t really "get" the problem.

The first strategy is to improve upon the traditional materialist argument that experiential states are necessarily identical to brain states (“internalist materialism”). Rather, we should identify the contents of experience with external happenings. Here, brain states represent contents which themselves are external to the body (e.g. the impact of light waves on the surface of the apple). I just saw a reference to this strategy in this review of Gregg Rosenberg’s book by Paul Skokowski. Skokowski misses the point. Arguing that (at least some of) the contents of consciousness (“qualia”) are outside the cranium is a good idea, but experience itself is not thereby reduced to a material explanation. First off, I still believe the contents have a qualitative character which resists reduction; but perhaps more importantly, qualia are only one aspect of the 2-sided nature of experience itself: phenomenal contents exist only in order to be subjectively experienced. As Rosenberg explains better than I can here, experience is a process which by its nature has inseparable dual aspects of an experiencer as well as the experienced. Even if you could reduce one aspect of the process (qualia) to the physical, you cannot reduce both aspects of the process to the physical without effectively eliminating experience from your world-model altogether. Now, to repeat my point from above, I do think the externalist concept of qualia is an important insight to consider. The best description of this I have read is from Max Velmans, whose book Understanding Consciousness I recommend. Because Velmans truly understands the issues here, however, he is not a materialist.

The second strategy is most famously included in Daniel Dennett’s Consciousness Explained. It is a straw man argument which tries to show that the experiencer doesn’t exist. It proceeds by first arguing that the common sense notion of our first-person experience requires the existence of a homunculus which is the observer of qualia (thus breaking into distinct parts what really is an intrinsically dual-aspect process). Then it proceeds to show that our everyday idea of the self (which is like a homunculus) is an illusory concept. Here, the valid insight is that our reflective, introspective sense of self is a fragile and flawed construct which is at least one step removed from experience itself. Many studies show the “self” to be less unified and robust than we tend to think, and Libet’s experiments even put into question whether this self-construct has the ability to impact our actions! But while careful phenomenology will concur that the reflective (deliberative, introspective) self is a psychological construct of sorts (see for instance this post), it has as its precedent and its foundation real and unmediated first-person experience. So the argument that our naïve idea of self is a flawed concept has no impact on the reality of experience itself.

Note on Terminology: I’ve been noticing that both advocates and critics are returning to the use of the term “materialism” rather than “physicalism” to label the position. The idea is that even though we know that the word “material” is unable to do justice to the nature of the phenomena described by present day physics, materialism seems an easier and less obscure term compared to physicalism. BTW, while the incidence of this may be declining, I continue to emphasize that it is a mistake to conflate materialism with naturalism. Naturalism is a broader term which includes materialism as a sub-theory but can also encompass theories which expand upon the entities and/or processes of physics without invoking traditionally “supernatural” entities or processes such as mind/spirit substances or ad hoc divine interventions.

Chalmers Still on the Case

David Chalmers (home page, blog) has a new paper (The Two-Dimensional Argument Against Materialism) which provides a definitive and comprehensive update of his work on the “conceivability argument” and related issues. Defense of this argument over the last decade has led him to broaden the turf: the bulk of the paper goes beyond the mind/body issue to a general defense of the premise that conceivability implies metaphysical possibility; in other words, an epistemic premise (about what one can conceive) can lead to a modal conclusion (about what is possible).

I won’t try to summarize the paper in this post (other than a bare-bones sketch of the original conceivability and 2-dimensional arguments below). It is very thorough and I found the cumulative impact of Chalmer’s responses to various critics to be powerful.

I also think a section tucked in late in the paper is thought provoking(Section 10 – Modal Rationalism). Here he steps back and wonders about the implications of his defense of the premise that conceivability implies possibility. He talks about the crucial role modality plays in our capacity for rational thought. We need modal concepts to analyze various phenomena rationally -- he says you might call this logical modality and make use of logically possible worlds. And given Chalmer’s analysis in the body of the paper, there is no reason to think logically possible worlds and metaphysically possible worlds are different animals. Interesting stuff. I wonder, as always, about the ontological implications of this also. By virtue of what outside of ourselves is our capacity for rational modal thought based?


Sketch of conceivability and 2-dimensional arguments:

The conceivability argument has 3 premises (my paraphrase of the basic argument – the argument is presented in iterations of increasing precision over the course of the new paper): 1. A world physically just like ours with no first-person conscious experience is conceivable. 2. If such a world is conceivable, it is metaphysically possible. 3. If it is metaphysically possible, than materialism is false, since materialism is a metaphysical thesis which says physical facts necessarily entail all other facts, including experiential ones. The paper responds to a wide variety of objections posed, but most of the attention is on the second premise.

Let me just mention that the two-dimensional argument of the title (a version of which was already included in Chalmer’s 1996 book) was constructed to respond to what was the most common sort of this objection to the second premise. It is one of this sort (exemplified by using an example of Kripke’s): we can conceive of a world where water is not H2O, but it isn’t metaphysically possible -- we know that water is H2O. Chalmers breaks down the idea that {“water is not H2O” is conceivable} into two senses: the first (primary) is that there is a possible world where there is watery stuff (doing the job of water) which is not H2O. This is clearly conceivable. The secondary sense is that the stuff in the possible world isn’t watery stuff – it really is water! – then it is not conceivable that this water is not H2O. It is the primary sense of conceivability which we utilize in Chalmer’s second premise.

Armstrong on Modality

I read D. M. Armstrong’s new book Truth and Truthmakers. Armstrong is a great philosopher and metaphysician. He is also someone who insists on a materialist-naturalist metaphysics: there is one actual spatio-temporal world, and nothing more. I wanted to see how he handled the topics of modal truths and causality (my recent posts relating to this topic are here and here). I came away very disappointed. So, below you will find the spectacle of an untrained layperson criticizing a brilliant and prominent scholar on a blog. I ask anyone interested to please be willing to point out where I’m mistaken here.

First, let me offer some praise and briefly lay some groundwork. Armstrong is engaged in realist metaphysics in a serious way. The idea of truthmakers is a great one: every proposition, if true, has a truthmaker which makes it true. There must be “some way the world is in virtue of which these truths are true” (p.1). By considering different kinds of propositions, we build up and fill out a metaphysical structure which provides the truthmakers needed. The book introduces and describes the truth-truthmaking relation and his methodology for using it for metaphysics.

Next, Armstrong reviews his building blocks for truthmakers, in particular, his “states of affairs”. His version of this idea, introduced in previous papers and books, is central to the system. I’ll sketch it here and mention a concern with this approach, before I get to the specific issues of modality and causality.

Armstrong asks: What is the truthmaker for a proposition that a particular has some property? It’s probably not enough to say that the truthmaker just is that particular. What if it has other properties besides the one in question – do they come into play? What if it has relational properties which involve other particulars – do they come into play? How do we combine and delineate the relevant parts needed for a truthmaker?

Armstrong digresses to briefly outline all the combinations of approaches to particulars and their properties which have been proposed: (are properties universals or tropes, do they adhere to a particular’s substance or is a particular just a bundle, etc.) Armstrong notes some of the advantages and disadvantages but also says not all of these are important for truthmaker theory (he happens to favor immanent universals as properties, by the way). The most crucial issue appears to involve how to think of the relation between the particular and its properties. Armstrong says there “must exist states of affairs to get us beyond the ‘loose and separate’ entities” and thereby provide the truthmaker. He says: “States of affairs must be introduced as additions to the ontology.” (Emphasis original p.49). So, states of affairs are introduced to hold the particular and its properties together by fiat.

Moving from old-fashioned individuals to states of affairs brings in extra ontology for free. It seems to me this is going beyond traditional materialism. I was impressed by Bill Vallicella’s in-depth critique of this notion in his recent book, but I won’t try to do justice to his argument now. I’ll just express my feeling that Armstrong’s binding of properties into individuals via states of affairs seems too easy.

You might also appreciate this when you see how Armstrong builds up to larger states of affairs. Larger states of affairs can encompass and bind smaller ones to provide appropriate truthmakers when needed. To provide a truthmaker for negative truths about the world (e.g. there are no unicorns), Armstrong utilizes the notion of a general or maximal state of affairs for the whole world. This mega-fact sets limits for what is actually in the world. The fact that there is no unicorn supervenes on the highest-order state of affairs. And just as we bound a property to a particular at no ontological cost, Armstrong asserts that the mega-state of affairs encompasses the conjunction of all its smaller constituent states of affairs with no additional cost, despite being “something more than the mereological sum of its constituents” (p.72). (there is an obvious regress issue here, but Armstrong argues it is a benign one.)

The issue of contingency vs. necessity comes up in a few contexts in the book, for instance in whether the connection between a particular and its property is contingent or necessary. But chapter 7 is explicitly on the question of what the truthmakers are for modal truths.

He starts it off thus: “It seems to me very surprising that so many good philosophers consider that huge metaphysical commitments must be made in order to give an account of these truths.” (p.83). He mentions David Lewis and Alvin Plantinga specifically. In Lewis’ system (simplified), something is necessarily true, if it is true in all possible worlds; it is possibly true if it is true in a subset of worlds. Something in our world is contingent if it is possibly not true in other worlds. Famously, Lewis says these possible worlds all exist concretely. Armstrong says “...we ought to be looking for quite modest truthmakers, fairly deflationary truthmakers, for these fairly unimportant truths of mere possibility.” (pp.83-4)

Here’s his truthmaker argument for a contingent truth (my paraphrase-see p.84 for this in his notation):
1. Assume that (state of affairs) ‘T’ is the truthmaker for truth ‘p’.
2. Assume p is contingent (my emphasis).
3. p entails 'it is possible that not-p' (from #2 and the definition of contingency).
4. Therefore, T is also a truthmaker for 'it is possible that not-p', and so T is a truthmaker for a contingent truth p. (This is via #1, #3, and from something Armstrong calls the 'entailment principle' that he argues for earlier in the book).

That's it: there's no more. But shouldn't truthmakers for modal truths distinguish a contingent truth from a necessary one? We could use this argument's structure equally well for the case where p is assumed to be necessary. Therefore there is nothing in the truthmaker which determines the truth to be contingent vs. necessary. Therefore it is NOT an adequate argument for a modal truthmaker at all!

I was stunned by what seemed to me to be the obvious inadequacy in the argument here. Could I have missed something? I have read the chapter more than once, but I'll keep at it. As I said in my introductory paragraph I invite anyone reading this that is familiar with this to “set me straight”.

Here’s something Armstrong says to close this section of the chapter (7.2, p.86): “…I still favor the hypothesis that particulars, properties, states of affairs and laws of nature are all of them contingent beings.” There is no argument for this, it is just a preference. While it is a hypothesis that certainly seems consonant with our human intuitions, it in no way follows from his system. With no way to distinguish the contingent from the necessary, I would think it would be more consistent and simpler for him to give up the intuition and argue that all of these constituents and relations are necessary.

I will skip over more material and just briefly touch on Chapter 10 which deals with causation. Armstrong wants to affirm real causal connections, not just Humean regularities. He terms this “singular” causation. How does one do this? He acknowledges the difficulty of the problem and mentions some possible approaches. You can’t just add causal connections between states of affairs without seeming to add still more gratuitous ontology. He favors an idea that the universals which are parts of states of affairs might be vehicles of causal or “cause-like” connections at a higher level than the state of affairs involved. Using universals to do the work would help explain the existence of lawful regularities across the states of affairs of the world.

This work on causal structure within his framework of states of affairs seems fine on its own. But I hold that without an explanation of modality, the discussion is relatively empty. I have thought the heart of real causality is the idea that things could have been some other way. So the earlier lack of adequate treatment of modality makes Armstrong’s discussion of causality of minor interest to me.