Upcoming GPPC events

Philosophy on Film Series - Estrangements

The Greater Philadelphia Philosophy Consortium is sponsoring a film series at the Bryn Mawr FilmInstitute again this year featuring commentaries by GPPC philosophers.  There are 3 films on consecutive Thursday evenings beginning March 29^th.

Causal Constraint

The notion of dispositional modality, discussed by Stephen Mumford and Rani Lill Anjum in Getting Causes from Powers, put me in mind of another analysis of the interplay between causation and modality: that of Gregg Rosenberg in A Place For Consciousness (2004).

 Recall (see prior post here) that Mumford and Anjum analyze causation in terms of dispositions, or powers. These powers tend toward (dispose toward) their manifestations -- they do not necessitate them. Necessity is not the modality of causation. In addition, it is argued that dispositional modality is distinct from standard philosophical notions of possibility (logical or metaphysical possibility). Dispositional modality (dispositionality for short) does not involve “pure” possibility, since only certain manifestations are possible. In Chapter 8 of their book, the authors say: “Dispositionality…can be understood as a sort of selection function…that picks out a limited number of outcomes from all those that are merely possible.” Also: “The idea of a selection function is simply one that identifies a subset from a realm of possibilities. (p.189)”

In his book, Gregg Rosenberg introduced a model of causation which featured a notion which seems related to the idea of the selection function: this was a constraining function on the space of possibilities. Rosenberg, unhappy with both the Humean perspective on causation, as well as the theories of causal responsibility or causal production on offer, endeavored in chapter 9 of his book to strip down the notion of real causation to a bare minimum. This led him to the following notion of “causal significance”: “The causal significance of a thing is the constraint its existence adds to the space of possible ways the world could be…Causal significance shows causation to be an operator on a space of possibility. (p.150 emphasis original)” And: “It is a theory designed to understand how constraints propagate, so it explains how the actual world comes to be just a sliver of what could have been. (p.152)”

I say they seem like related notions, but constraint could be viewed as the negative image of selection. Selection picks out a few possibilities, while constraint rules out all of the others.

I find causal constraint to be a beguiling idea. Tentatively, it would seem to leave “pure” possibility in place as the fundamental metaphysical notion, in constrast with Mumford and Anjum’s argument for the irreducibility of dispositional modality.

Short Review of Getting Causes from Powers

In this book, Stephen Mumford and Rani Lill Anjum present their theory of causal dispositionalism, that is, causation based on dispositional properties, or powers. I highly recommend it to anyone interested in the philosophy of causation.

Powers do the causal work in our world, according to the authors: effects are brought about by powers manifesting themselves, and the manifestation is itself a further power or set of powers.

A central idea is that powers don't necessitate their manifestations - they dispose toward them. Causality has long been associated with the idea of necessity, and necessity (and the sense of constant conjunction) is too strong to describe causation. The main insight here is that other factors can prevent or interfere with the expected manifestation (and, indeed, they often do).

To help demonstrate how a disposition can be enhanced or, importantly, hindered by other powers, the authors develop a vector addition diagram. Only when the sum of vectors (with various strengths and directions) exceeds some threshold do we get the manifestation. They extend the model to more complex scenarios to argue that the model is robust enough to explain non-linear and even "emergent" behavior.

In addition to arguing strongly against necessity, the authors want to overthrow another usual notion. The authors reject as misguided the typical "two-event" conception of causation, where cause is temporally prior to effect, in part because no one has a compelling account of how you get from one to the other. Instead causes and effects are simultaneous - they are two aspects of a temporally extended process which brings about a change.

An important and creative part of the book explores the distinctive modality of dispositions in more depth. Dispositional modality (weaker than necessity but stronger than "pure" contingency) is the primitive and fundamental modality of nature. We derive necessity and possibility from our prior experience with dispositionality. Mumford and Anjum argue that we do indeed perceive causation, and present what they see as the clearest examples of this in the case of bodily sensation and specifically proprioception.

The book concludes with a compelling application: showing how the theory fits with processes studied in biology and genetics.

More on Causation and Reduction to Physics

I finished reading GettingCauses from Powers by Stephen Mumford and Rani Lill Anjum.  I recommend the book highly to anyone interested in causation, and I’ll be thinking about many of its arguments and themes for a long time to come.

As touched on at the end of my prior post, one possible challenge to models of causation, including the thesis of causal dispositionalism presented in this book, is the fact that causation doesn’t seem to comport well with physics.   The authors acknowledge this in their first chapter, referencing Russell’s discussion in his "On the Notion of Cause” (1913).  The issue is that dynamical equations associate states of a system with points in time, but nowhere do they invoke the idea of causal production.  They are symmetric with regard to time, where causation is not.  Mumford and Anjum respond in a couple of ways.  First, they say, the fact that causation doesn’t appear at the level of physics doesn’t mean it isn’t present at larger scales:  the reducibility of all phenomena to physics is a controversial idea which we are not compelled to accept.  We don’t know that physics represents a special fundamental level of reality in any case.  And given the provisional nature of scientific theories, should we let them trump our metaphysical reasoning?

This issue recurs as the book progresses.  In Chapter 4, the authors show how the composition of powers in causal situations can plausibly model emergent phenomena in the form of novel powers.  So the theory is robust if it does turn out that reduction of the phenomena in the special sciences isn’t possible.  And the final chapter of the book (ch.10) presents an interesting and persuasive application of the theory by showing how causal dispositionalism fits quite well with examples of processes studied in biology (including genetics).

Just like the situation in philosophy of mind, one must be cautious about drawing metaphysical conclusions from the perceived character of formal physical theory.

Determinism Doesn’t Imply Causal Necessity

A key part of the argument for causal dispositionalism in Mumford and Anjum’s Getting Causes FromPowers is the case against causal necessitarianism (chapter 3 in the book).   Causality is commonly thought to imply a necessary connection between cause and effect:  the authors say this is a mistake, and that the proper modality of causation is dispositional.   Causes dispose toward their effects - they don’t guarantee them.  The insight here is that other factors can prevent or interfere with the expected manifestation (and in everyday experience, they often do).   In fact, such prevention is always possible in causal situations, and if one moves to evade this fact by stipulating that prevention or interference is impossible, then the resulting necessity is not really coming from the causal process itself, but is being imposed in another way.

To see this, suppose I specify the causal factors involved in some manifested effect, and then someone points out another factor which could possibly interfere (despite my match being dry, a proper striking motion made and sufficient oxygen being present, a gust of wind might prevent the match from lighting).  Can’t I modify my scenario to specify that the threatening factor is absent (the wind is calm)?  Leaving aside the potential problem of listing an absence as a causal factor, the objector might present another possible interferer (a passing car might splash water on the match as it is being struck).  So, then I, in turn, specify that there is no nearby traffic, and so on.   In fact, no finite list of factors will ever suffice to rule out every interferer (however unlikely).  And by the time one is led to propose a “catch-all” condition, covering the whole state of the universe, we’re really not talking about a process of causal production anymore.

The authors note something interesting here.  They say that their argument against causal necessitarianism does not mean they are ruling out determinism.   This was a helpful observation for me because I have been guilty of confusion on this point.  One might think “determinism” means “causal determinism” which means “causal necessitarianism”.  However, determinism can be specified in other ways (including what might be the most common conception – see below).  Then causal dispositionalism could be compatible with determinism.  There is a causal process, and while it doesn’t necessitate effects, necessity is imposed in another way.

Note, that for the moment, we are leaving aside the idea of irreducibly probabilistic causation.  Such causation is likely a feature of our world (in fact I think the a posteriori case for it is nearly airtight), and therefore determinism is false.  But disentangling these ideas remains philosophically valuable.

As Mumford and Anjum say:  “The core idea in determinism is the fixity of the future by the past (p.75)” If one wanted to build a model of a deterministic world, causal necessitarianism is probably not the best tool, since the causal process doesn’t promise to cover all the possible loopholes - for instance if there are such things as uncaused events, then they would not be addressed.

It seems to me that the most common notion of determinism (probably inspired by classical mechanics) is this:  given a specification of all facts, and given comprehensive deterministic laws of nature, then the future is fixed.  There is no reason here to even mention causation – it adds nothing to the scenario.  One could be a Humean about causation and still endorse the deterministic picture.  And given the fact that in this physics-inspired vision the mathematical depiction of laws is symmetric with regard to time, it would be equally true to say that the past is fixed by the specification.  This is inconsistent with causation, which is not a symmetric process.  One might believe that the mathematically specified physical laws comprise a model of a causal world, but the laws themselves don’t constitute a theory of causation, and may very well be inconsistent with the idea of a causal process.

On this last point, I recalled a paper I had read a few years ago by Carl Hoefer: “Causality and Determinism: Tension, or OutrightConflict.”  In this paper, Hoefer defines a deterministic world specifically as one governed by deterministic micro-physical laws, and then goes on to argue that this definition is inconsistent with the presence of causation, using several philosophical theories from the literature as examples of how causation might be characterized.

A Note on Events and Causation

Presently I’m reading GettingCauses From Powers by Stephen Mumford and Rani Lill Anjum (and have finished six chapters out of ten).  I expect to blog more about this book, of which I think very highly.  I just wanted to very briefly comment on events, inspired by the treatment they are getting so far in the book.

Years ago, influenced by reading (later) Russell and Whitehead, I acquired the notion that (all else equal) there is an attraction to an ontology which gave a leading role to events rather than one primarily featuring substances (or objects) and their properties.  There seemed to be more potential for explaining the dynamic aspects of nature (including mind).

But while there has been an active modern debate on the nature of events, the most common depictions don’t seem to offer specific advantages to an event-focused ontology.  To greatly simplify, it seems philosophers would model events either as property exemplifications, in which case they are in danger of seeming much like static facts or states of affairs; or else events would be associated with spacetime locations, in which case they are little distinguished from objects, which are the quintessential occupiers of spacetime.  (The SEP article on events is here; an IEP article with additional focus on the theories of Kim, Davidson, and Lewis is here).  These sorts of models of events don’t seem to bring differentiated resources to metaphysical theorizing.

The goal of the Getting Causes From Powers book is to develop a theory of causation based on dispositional properties, or powers.  While powers play the leading role, their theory incorporates an intriguing view of events (at least causal events:  they don’t take a position on whether there are other sorts).  Specifically, causal events, which are manifestations of powers, are temporally extended processes.  The authors reject as misguided the typical “two-event” conception of causation, where cause is temporally prior to effect, in part because no one has a compelling account of how you get from one to the other.  Rather causes and effects are simultaneous – they are two aspects of a process which brings about a change.  Very Whiteheadian!

Do We Need Essences?

I’ve just been starting to read and think more about essences, in particular the debate which has followed Kit Fine’s argument in “Essence and Modality” (1993) that essences cannot be understood in modal terms.  The modal understanding is that an essential property of an object is one is must have of necessity (in order to be that object), while properties it can (possibly) do without are accidental.  Fine, on his way to advocating a definitional notion of essence, said the modal understanding was too broad:  an object may have certain necessary attributes which are intuitively not essential.  In the paper, he offered some examples intended to bolster this point.

Now I’ve read a few papers which take issue with Fine’s argument. In particular, one line of protest, due to Michael Della Rocca, notes that Fine’s examples are of necessities which seem trivially true of all objects or existents, and the modal understanding of essence can be recast by a focus on non-trivial necessary properties.

For present purposes, though, I want to concede that there is an intuitive sense that essence seems prior to its modal understanding (even if the latter turns out to be extensionally equivalent):  when I try to think of what properties are necessary to an object I seem to be appealing to some non-modal definition I have in mind.

But do we really want to add essences as irreducible elements in our ontology? While I’m attracted to some Aristotelian or neo-Aristotelian notions (such as causal powers), my inner Occam wants to resist essences.

One clue to a way to think about this dilemma occurred to me while reading Michael Gorman’s paper, “The Essential and the Accidental”.  Gorman highlights one of the passages about the nature of essential properties discussed by Fine in another paper (“Senses of Essence”, which I have not read):  “An essential property of an object is a constitutive part of the essence of that object if it is not had in virtue of being a consequence of some more basic essential properties of the object; and otherwise it is a consequential part of the essence.”  Perhaps this constitutive subset should be the real target of our idea of essence.

While Fine’s idea of distinguishing consequential properties from constitutive properties is one of logical consequence, Gorman takes this as an inspiration to develop an account of essence that depends on the notion of explanation. Perhaps the essential properties of an object are those which cannot be explained by appeal to other characteristics (while accidental properties are those that can be so explained).  The paper elucidates this argument and considers possible objections.  This view is distinct from the modal understanding because it can accomodate necessary but non-essential properties.

For myself, being in a very preliminary stage of studying these issues, I reserve my opinion about Gorman’s particular strategy, but am led to a desire to link essences to some other metaphysical problem, such as causation (which is obviously related to explanation).  By the time we conceive of an object, we already have in mind something which has been caused and has its own causal powers.  And we already know (I believe) that modality alone, say a mosaic of categorical properties distributed across possible worlds as in David Lewis, doesn’t provide a theory of causation.  So, it shouldn’t be a surprise if there is a problem with defining essence solely in modal terms if essence relates to causation.   I’ll try to see what’s been written along these lines.

UPDATE: 20 November 2011:
Kathrin Koslicki has posted a preprint of a chapter for a forthcoming book called "Essence, necessity, and explanation" which fleshes out a discussion similar to Gorman's.  She uses an analysis of Aristotelian notions of explanation, including cause, to account for how necessary but not essential properties follow from constitutive essential ones.  However, the scheme here is that essence is basic and prior to cause (I was wondering if there was a way to reverse this priority.)

Philosophy for Children Forum: 29 October

Coming up very soon is the next event on this year’s GPPC program: our Public Issues Forum. The topic this year is Philosophy for Children. The date is Saturday October 29th, 1pm, at the University of Pennsylvania. The event is free and open to the public.

Dispositional Modality as Restricted Possibility

I’ve been interested in the metaphysics of dispositional properties (or powers), and I’ve ordered Getting Causes from Powers, a new book from Stephen Mumford and Rani Lill Anjum. I look forward to reading this later in the fall, but it the meantime I have read a couple of related papers by the authors (see an earlier post here).

In “Dispositional Modality” Anjum and Mumford argue that the modal value of dispositions is distinct from necessity and possibility: it is described as “sui generis” and “irreducible”. What I thought was interesting, though, is that the authors themselves include a nice account of dispositional modality in terms of restricted possibility, which seemed to me had the flavor of a reduction.

I’ll pass over the first several sections of the paper, which covered some familiar ground: the fundamental disagreement with Hume about powers; the failure of the semantic reduction of dispositional ascriptions to conditionals; and the fact that dispositions, by their nature, clearly do not necessitate their manifestations (they are disposed toward, or tend toward their manifestations).

So, dispositional modality is distinct from necessity, but what about possibility? In section 5, Anjum and Mumford argue that dispositional modality is also distinct from possibility, in the sense that it is different from “pure” possibility. By pure possibility, the authors mean the broadest sort of logical or metaphysical possibility. A glass vase is disposed to shatter when dropped. One might suppose it is logically possible that the vase will turn to jelly when dropped, but it is clearly not disposed to do so – at least in our world.

The authors say we might think of dispositional modality as a subclass or restricted version of possibility. But this is already a familiar idea. Modal theorists talk about various nested classes of possibility: logical possibility (typically the broadest notion), various formulations of metaphysical possibility, and nomological possibility -- the subclass which holds the laws of nature fixed (some philosophers would identify one or more of these). Anjum and Mumford see dispositions as giving rise to “natural” possibility: “The reason some things are naturally possible is because there are dispositions for them.”

The authors don’t elaborate greatly on this point, but it seems as if natural possibility is the set of all the possibilities inherent in the dispositions contained in the state of the natural world at a given time. Building on this idea: when it comes to individual natural objects or systems, in saying they possess dispositional properties (or powers), we might equally well say they possess a certain restricted bundle of possibilities. Then we might turn to a discussion of how causation is explained in terms of the “actualization” of some of these possibilities (compare the “manifestation” of a disposition), perhaps depending on how a system interacts with other systems which similarly bear possibilities.

If one can retell the story of dispositions with restricted sets of possibilities, might this be a reductive analysis? It’s not completely clear to me, because one might say the introduction of restricted sets of possibility of the type needed is an irreducible extension of our notions of modality. And perhaps the idea of an object bearing a set of possibilities, rather than bearing properties, isn’t coherent (but maybe the terminology can be worked out). In any case, this paper’s comparison of dispositional modality to the idea of restricted possibility was very thought-provoking.

Aaronson on QM and Free Will

One thing that has frustrated me in the past is the fact that folks tend to think indeterministic means “just random”, where by random they mean some stochastic process (like a dice roll) where one can’t predict which outcome will be chosen from some probability distribution. Quantum indeterminism doesn’t work this way, but it’s a difficult subject and experts don’t agree on exactly how to characterize it. It seems clear one cannot simply use a “frequency" interpretation, the way you can with a classical stochastic system. There seems to be something more involved, something spontaneous which resists reduction, but I have a hard time being more precise about this.

Computation theorist Scott Aaronson (home page, blog) recently gave a presentation on free will (at an FQXi conference) which was very thought-provoking (see this Sciam piece with helpful links), and had an interesting take on this issue.