Author Archives: Trin Turner

About Trin Turner

Ph.D candidate in the Philosophy of Science and Biology

Thinking About Causality (Part 2)

If you’re following along with the discussion of causality via the commentary on Judea Pearl’s text that we’ve begun here at TMD, the good news is that we’re still at it…the bad news is that we’re still debating (check out the comments section on Part 1) the metaphysical implications of this view I’m attributing to Pearl in order to make my own (seemingly crazy) view seem more mainstream. So much for progress…

The sticking points thus far seems to be two: whether and in what ways this minimalist view of mine is anything different from Hume and just how serious is this minimalist view anti-metaphysical. I’ll let Aristotle demonstrate my position:

I'm right behind Aristotle pointing down to the ground just like he is.

For my money, philosophical questions are best when they’re epistemological (when they’re about our beliefs of the world and the logical and evidential relations therein etc.) and worst when they’re metaphysical (when they’re about the “fabric of the cosmos” and the way things “are” etc.). This puts me in an interesting position since I am fascinated by causality, a topic that has been the purview of metaphysicians since there were metaphysicians and philosophers falling down wells and what-not. I fully accept that this puts the burden fully on me and that’s fine. Here’s what Pearl says:

But causality is not mystical or metaphysical. It can be understood in terms of simple processes, and it can be expressed in a friendly mathematical language, ready for computer analysis(p.427).

Now, to be fair, Pearl is a brilliant computer scientist and mathematician, but not a brilliant philosopher by trade, and sometimes philosophers tend to hold others to a very strict manner of speaking even when it is ill-advised to do so. Maybe he is making a grand claim about the metaphysical status of causality, maybe he’s just being a flamboyant writer. Who knows. The rest of the book (that we will start focusing upon this week…) is devoted to the mathematical analysis of causal claims and providing a set of tools for professional researchers to formulate and test causal hypotheses; it is not a book about the metaphysics of causation. But, and here’s the sticking point, it needs to be a book about the metaphysics of causation even if it’s not. Simple as that. So here’s what I propose.

I think that we should start with the simple and provocative position I described in Part 1 and see whether Pearl’s mathematics can do everything we want out of a formal model of causation. Then we should see whether it can stand up to philosophical attention…serious philosophical attention concerning those tricky metaphysical issues I’m hoping we feel safe to abandon once we’re finished with the book.

So here’s what I propose: we start out with the assumption that causation is an essentially pragmatic notion, that causal hypotheses are the product of isolating a system, describing that system as a composite of discrete entities and relations, and examining the inter-relations between members of that system in an artificial way (which is not a dig against the scientific method by any means; it’s just the way research has to be done). The challenge is to see how far we get using that minimalist concept.

I’ll leave you with a paraphrase of van Fraassen’s concerning causal explanations. Imagine some committee is charged with adjudicating responsibility of some particularly bad car accident. On the committee is an engineer, a physicist, a civil planner, an auto mechanic, a psychologist, and a cognitive scientist. Now asking for who or what is responsible for a car accident is clearly a request for a causal explanation (“what or who caused this accident?” or “Who or what is at fault here?” etc.). van Fraassen asks the reader to imagine what kinds of explanations we’re going to receive from the respective committee members. The civil planner will focus attention on the placement of traffic lights, their timing periods, the placement and state-of-maintanance of the bushes and trees, etc. of the location where the accident occurred. A physicist will give an explanation involving static and kinetic friction, applied force, braking distance (a function of acceleration, initial speed, and friction) etc. A mechanic will give an explanation involving the operation of the braking system, the state of the tires, the coolant system (I guess, I’m a bad mechanic…). The cognitive scientist a will discuss reaction times of the human brain in relation to the speed of travel, and attention. The psychologist may talk about the mental state of the driver at the time of the accident (maybe he was worried about work, or was cheating on his wife and was thinking about how to resolve that). The point is two-fold: first, not all or even most of these explanations can be reduced to one another (things just don’t reduce down to physics like most used to believe); second, there is no clear sense in which any one of these can be more “right” or correct than another. How do we quantify the relative significance of being preoccupied while behind the wheel with the state of the bushes partially occluding the other traffic lane etc.? For van Fraassen, there are as many legitimate causal explanations as there are people to give them. This is the pragmatic conception of causal explanations (it need not reduce down to my causal minimalism, but I like to think it does).

So what do we make of this? If causation were some metaphysical structure to the world, then there should be “a cause” of that car accident? But what does it mean if there isn’t “a cause”?

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How Amazingly Amazing are Parasitoids (…and Natural Selection)?

I had the great pleasure yesterday of walking Rudy Raff back to his office after he gave a lecture on evolution to an auditorium full of undergraduates. Somehow we got to talking about this monster:

Let me introduce you to Cymothoa exigua, otherwise known as the Tongue-Eater or sometimes as the Tongue-eating louse. This little guy enters the gills of a fish and begins comsuming that poor fish’s tongue (its predator phase). When the tongue has either been wholly consumed or necrotic the tongue-eater attaches itself to the now-empty base where the tongue used to be. Helpfully (!!!), that tongue-eater then allows itself to be used as a new tongue for its host (the parasite phase).

One more photo just to make sure you’re paying attention and to confirm that I’m not making this up:

This species takes control of its host’s organ, consumes it, and then functionally replaces that organ for the duration of its life! Like I said, it is both a predator and a parasite, so once it’s attached and performing tongue-y activities, the tongue-eater and the host live happily ever after.

If I had more time I’d mention environmental specialization and niche exploitation, but I’m sure you’re already thinking along those lines…

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Thinking About Causality (Part 1)

Starting at the end of a book is typically a bad idea, but in this case I think it’s enlightening to begin at the end, as it were. For one, Pearl makes some of his most dramatic claims and I want to draw attention to those claims and treat them as promissory notes to be cashed in by the final substantive chapter. I also want to ensure that these claims are capable of holding up to philosophical scrutiny.

My (newest) position concerning causality is one that I’m fairly confident Pearl shares, which is good because, for one, it’s an unpopular position and, two, it’s always nice to have friends. Lately, I’ve been entertaining the notion of an “epistemic” conception of causality, which means that causation need not be thought of so much as a feature of the world but as a feature of the way we interpret the world. These are very different interpretations of causation since one implies that causal relations are things in the world (whether we observe them or not) and the other implies that causal relations are items of our understanding of the world (which may not be there if we’re not here to observe them). I think Pearl holds this position and I’ll give you some reasons to back up my claim.

First, when discussing the problem Bertrand Russell has regarding the problem of causation, Pearl is quick to point out that the asymmetry of causal hypotheses is not due to the structure of the universe as such, but is instead due to the ways in which researchers go about studying some small part of any physical system. Pearl says:

The lesson is that it is the way we carve up the universe that determines the directionality we associate with cause and effect. Such carving is tacitly assumed in every scientific investigation (p.420).

Now, while not a definitive acceptance of this epistemic conception of causality, it is still telling, I think. Pearl is responding to Russell’s criticism that in advanced physics causal language never comes up by arguing that the language of causality only comes into the picture when researchers focus on areas of the physical universe that are not maximally inclusive. In other words, it is only in isolated subsystems that causality appears: take a subset of the interrelations between physical objects and you will find causal relations; take the system as a whole and those causal relations disappear and the system seems symmetric.

There is something very interesting going on here with the related notions of “boundary conditions,” “input/output relations,” and “background conditions.” When we first isolate some subsystem and then characterize it in terms of inputs and outputs we draw a boundary around some phenomenon and, in so doing, create this asymmetry between what was designated as the input and the output. This idea is worth exploring further and, I’m sure, will become a much-debated item of discussion on this blog. It’s also in my dissertation, so there’s that.

Now, to be fair to the realist and a possible realist-reading of Pearl, declaring something to be an input does not mean that one must be an anti-realist regarding the nature of that element (inputs can be just as real as anything, after all). Now whether Pearl is or is not a realist about causation is going to be one topic of this multi-part discussion, but I am going to try to defend this rather extreme position I’ve outlined above and argue that, in fact, it is the labeling of certain phenomena as “input/output relations” that provides the directionality and the asymmetry of our causal hypotheses about those phenomena. So I agree with Pearl when he says that it is the act of investigation of an aspect of the universe that brings about causal language and I’m going to take him literally and defend the position that causation is just that; namely, the way in which we characterize systems in terms of asymmetric relations between elements of that system.

Like I said above, this is a highly unpopular and idiosyncratic position to hold, so I’m very interested in hearing your views.

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Filed under Bertrand Russell, Causality, Philosophy, Physics, Science

Causality in the Press…& News!

So a friend sent this article from Wired.com yesterday. On the plus side, it’s fantastic whenever topics such as causality make it into the popular media. For one, it makes my job look at least somewhat sexier and seemingly somewhat more relevant (just go with it). The downside, however, is that many times the simplifications that go into such a piece are typically deal-breakers and, well, oversimplifications.


Yes, that’s billiard balls. If you know your David Hume then you’re at least making some sort of face at my lame attempt to be clever…

Sadly, however, I have many points of dispute with the piece, including:

(1) The title is just silly, right? How is it a failure of “Science” if many (or even all) of our causal hypotheses turn out to be wrong? Is this a complaint that “science is hard”? Because that’s certainly true, but let’s not forget that it’s the same set of methodological practices that allow one to empirically reject bad causal hypotheses that allowed one to initially formulate those hypotheses in the first place. So, contra the author, it was the failure of those hypotheses (those reductionist hypotheses, note) and not a failure of science that is to be blamed.

(2) The author seems to burden “Science” with a particular interpretation of causation. But there’s two problems here; first, it’s a narrowly reductionistic and linear-style interpretation of causality he/she has assumed applies to the whole realm of scientific research; second, causal talk has not really been welcome in fundamental physics for around 100-150 years. Now, I disagree with the absence of causal talk in physics for many reasons, but it’s a gross error to generalize across disciplines and assert that this interpretation of causation holds across them all.

(3) This narrow interpretation of science, what the author rightly calls “reductionistic” is one and only one of many possible ways of conceiving of causality (and for discovering it via causal hypotheses testing). There are many proponents of causation in science who would flat-out deny that it works in the way suggested by reductionist approaches.

Anyway, feel free to read the article and argue with me.

Now the other bit of news. A few of us here at The Modern Dilettante have decided to initiate a new element to the blog; namely, a critical commentary on a series of texts, the first of which is called Causality: Models, Reasoning and Inference. We’re hoping to begin this commentary in the next week, so feel free to chime in or just follow along. We will try to keep the more technical and mathematical elements to the bare minimum and will focus instead on providing a clear and concise commentary (but it is a math book, after all).

But here’s a question. Since thinking critically about causation began with Hume…

…should we start there with an introduction to his thinking on the matter? It’s still highly relevant and every serious treatment of causality mentions his name in the first or second sentence of their work.

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Filed under Mathematics, Philosophy, Physics, Science, Site News

Trin Turner:

Interesting read

Originally posted on EvoAnth:

Ordinarily I give posts from the Institute of Creation Research (ICR) a wide birth because there is already a fine blog dedicated to commenting on what they have to say. Their latest post, however, requires comment. Mostly because they mentioned evolutionary anthropology by name (and as an egotistical male, I take any critique of my subject as a direct attack on me).

But before I defend myself, some background.

Göbekli Tepe is the oldest religious structure found so far, consisting of massive stone pillars, engraved with many kinds of animals. The complex would’ve required extensive co-ordination and effort to construct.

The entire complex

It has been placed in the pre-pottery Neolithic A period (around 12,500-9,000 year ago, depending on who you ask) based upon the artefacts found there. These dates have been further refined via radiometric dating (including U-series & c-14) to around 12,000 years ago.

This places it around, if…

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Darwin’s One Long Argument

My post the other day on the final passage in The Origin got me thinking about how amazing that book really is.Michael Ruse and some others have argued that The Origin is one long argument…one long 459pp. argument. While I think that it’s a debatable point, there’s no mistaking the brilliance and the continuity with which Darwin carried out his argument for evolution by means of natural selection.

Here’s a picture of Darwin’s notebook, the page where he first conceived of his “Tree of Life,” taken along with him on his HSS Beagle journey, and which displays the dynamics of his thought in action. Note the “I think” in the corner. Amazing! I got to see this in person once and it was a nice and humbling experience.

But what is incontestably amazing is the simplicity of Darwin’s central argument. I’ll sketch it out and then provide a more rigorous treatment. Here’s the sketch:

As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form (1859; p.5).

Nice, huh? Note how un-teleological (purpose-driven) the process is; many, many people, evolutionists included, fail to fully get that. Here’s the more rigorous argument (where P stands for “premise” and C for “conclusion”):

P1: That there exists an appreciable amount of variation of characteristics between organisms.
P2: That there is some process by which traits pass from generation to generation (inheritance).
P3: That individual organisms reproduce many more offspring than can be sustained within any given environment.
C1: Therefore, organisms will compete for a set of limited resources (from P3).
C2: Given C1 and P1, Some variations will be more beneficial to individual organisms who possess them.
C3: Given C2, individuals possessing “profitable variations” will have a greater capacity to survive that competition for limited resources.
C4: Given C2 and C3, P1 and P3, these individual organisms will also possess a greater likelihood for producing more offspring than competitors.
C5: Given the above, individual organisms with “profitable variations” will be more likely to produce offspring and, given that there is some mechanism of inheritance, these “profitable variations” stand a better chance of being passed in to future generations. In other words, that certain variations will be naturally selected and passed to future offspring.

Now, note that Darwin had no idea about Mendelian genetics. Mendel was doing his work a few decades after the publication of The Origin and was, alas, in German, so Darwin never read it. But that’s irrelevant since the argument only needs “some” mechanism of inheritance in order to be successful. The inheritance problem bothered Darwin and bothered him more when G. Mivart (I think) leveled the “blending inheritance” problem at Darwin and his followers, but that problem was solved by Mendelian genetics (but not by Mendel himself) and the Modern Synthesis of Fisher, Haldane, and Wright (I’ll post on that later…).

But just appreciate the utter simplicity of Darwin’s argument and note that this structure works for any type of selection..for any set of organisms anywhere and anywhen, so long as those meager premises are fulfilled! And people are impressed by Einstein’s equation for its generality…

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Robustness and Climate Science

This is a nice video of Michael Mann (the guy who developed the horrifying “hockeystick” graph) discussing climate change.

I wanted to point out two things in this post. First, the major climate models in use today are open source; i.e., the code for the mathematical models are freely available to the public. Check out, for example, the mathematical model developed for NCAR called the CESM (community earth system model), which is freely available along with the relevant dataset. Interestingly, that seems to put climate change antagonists in an “uncomfortable” position since, for one, all of the relevant material for making an informed assessment of the science is right there for the perusing.

The second thing I wanted to point out is that most of the climate models that are in use today (which are ridiculously mathematically complex) generate robust results. What this means is that the models are producing exact or very similar predictions for numerous iterations of the model. Now what makes that “reallllly” interesting is that the parameters and values for the multitude of variables that appear in the models are different!

Let that sink in for a second….

Why would different and mathematically distinct models of some phenomenon ever be expected to generate the same predictions when they have different parameter values etc? These models share “a common causal core” which is, I’m sure you’ve guessed it, the Greenhouse Gas hypothesis. So you dump this hypothesis (that greenhouse gases possess such-and-such chemical and physical properties) into a ton of very different models and you get the same result; e.g., that global warming is a reality and that we are most likely the cause of it.

Coincidence? Hardly. Discuss.

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