Cause and effect has been central to many arguments in science, philosophy and theology down through the ages, from Aristotle’s four causes[1] down to the present time. It is has frequently been used in philosophy and Christian apologetics in the form: The law of cause and effect is one of the most fundamental in all of science. But it has it naysayers as well. For example, Bertrand Russell (1872 –1970): All philosophers, of every school, imagine that causation is one of the fundamental axioms or postulates of science, yet, oddly enough, in advanced sciences such as gravitational astronomy, the word “cause” never occurs. … The law of causality, I believe, like much that passes muster among philosophers, is a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm. You can accuse Russell of many things, but being mealy-mouthed is not one of them. Karl Pearson (1856 – 1936), who has been credited with inventing mathematical statistics, would have agreed with Russell. He never talked about causation, though, only correlation.
One of the people who helped elevate cause and effect to its exalted heights was David Hume (1711 -1776). He was a leading philosopher of his day and known as one of the British empiricists (in contradistinction to the continental rationalists). Hume was one of the first to realize that the developing sciences had undermined Aristotle’s ideas on cause and effect and he proposed an alternate in two parts: first, Hume defined cause as “an object, followed by another, and where all objects similar to the first are followed by objects similar to the second”. This accounts for the external impressions. His second definition, which defines a cause as “an object followed by another, and whose appearance always conveys the thought to that other”, captures the internal sensation involved. Hume believed both were needed. In thus trying to relate cause and effect directly to observations Hume started the philosophy of science down two dead ends streets: one was the idea that cause and effect was central to science and the other lead to logical positivism.
Hume’s definitions are seriously flawed. Consider night and day. Day invariably night and the two are thought of together but night does not cause day in any sense of the word. Rather, both day and night are caused by the rotation of the earth, or, if you prefer, a geocentric frame, by the sun circling the earth. The true cause has no aspect of one thing following another or one causing thought of the other. And the cause does not have to any way resemble the effect. One can find many other similar cases: it getting light does not cause the sun to rise despite it getting light before the sun rises; it is the sun rising that causes it to get light. Trees losing their leaves does not cause winter but rather the days getting shorter causes the trees to lose their leaves and is a harbinger of winter. The root cause being the tilt of the earth’s axis of rotation with respect to the ecliptic.
As just seen, cause and effect is much more complicated than Hume and his successor thought, but not nonexistent as it detractors maintain. In the words of the statistician: correlation does not imply causation. However, it can give a strong hint. The cock crowing does not cause the sun to rise but the correlation does suggest that the sun rising might just motivate, if not cause, the cock to crow. Similarly, consider lung cancer and smoking. Not all people who smoke get lung cancer and not all people who get lung cancer smoke (or inhale second hand smoke). Nevertheless, there is a correlation. It was this correlation that started people looking to see if there is a cause and effect relation. Here we have correlation giving a hint; a hint that needed to be followed up. And it was followed up. Nicotine was found to be carcinogenic and the case was made convincing. A currently controversial topic is global warming and human activities. Here, as with smoking causing cancer, we have both correlation and a mechanism (the greenhouse effect of carbon dioxide and methane).
Cause and effect went out of favor as a cornerstone of science about the time quantum mechanics was developed. Quantum mechanics is non-deterministic with events occurring randomly. Within the context of quantum mechanics, there is no reason or cause for an atom to decay at one time and not at another. The rise of quantum mechanics and the decline in the prominence of cause and effect are probably indeed cause and effect. However, even outside quantum mechanics there are problems with cause and effect. Much of physics, as Russell observed, does not explicitly use cause and effect. The equations work equally well forwards or backwards, deriving the past from present as much as the future from the past. Indeed, the equations of physics can even propagate spatially sideways rather than temporally forwards or backwards.
In spite of all that, the idea of cause and effect is useful. To understand its limitations and successes we have to go back to one of my mantras: the meaning is in the model. Cause and effect is not something that can be immediately deduced from observation, as Hume implies, but it is not a meaningless concept as Russell said or the physics discussion above might seem to imply. Rather, when we develop our models for a particular situation the idea of causation comes out of that model, is part and parcel of the model. We believe that the post causes the shadow and not the other way around, because of our model on the nature of light and vision. Similarly, the idea that the earth’s rotation causes day and night comes out of our model for light, vision and the solar system. The first chapter of Genesis indicates that this was not always considered obvious[2]. That smoking causing lung cancer is part of the biological model for cancer. That human activities causing global warming comes out of atmospheric modeling. But arising from a model does not make cause and effect any less real nor the concept less useful. Identifying smoking as a cause of cancer has saved many lives and identifying carbon dioxide and methane as the main causes of global warming will, hopefully, help save the world. Cause and effect may not a cornerstone of science but it is still a useful concept and certainly not a relic of a bygone age.
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Tags: Bertrand Russell, cause and effect, Hume, philosphy of science
An excellent post, and I hate to nitpick on something that’s so off your point, but the cause and effect between global warming and human activities are really only controversial in North America, much like the planet being 6000 years old is not really heard outside of that continent. What is potentially controversial in the rest of the world is what to do about, what the costs and benefits are and how these should be distributed.
However, I did have a German Herr, Doctor, Professor challenge me on the issue.
Well, I’m convinced human activities indeed cause global warming. But, as far as I can tell, it’s controversial in Europe, too. And there is not only one “German Herr, Doctor, Professor”, there are others. So, Johan, your comment provokes the joke of you being a controversian denier.
The value of cause and effect theory, at least a very important one of them in my opinion, is to indicate the one-way effect on the dimension of time. It also enlights us to think about the ultimate cause and concept like singularity and big bang theory.
Correlation could not be used to explain the famous “twin paradox” in the theory of relativity. So they are somehow not comparable.
Text very fair.
But I would not say that quantum mechanics is indeterministic. I will say that it is deterministic but not accessible.
Not accessible because they do not know all the initial conditions. This is already true in classical mechanics.
But above all, in quantum mechanics, determinism is invalid because the observer changes the result.
Conclusion: The research model of understanding does not go through precision.
Ps just to the author in: Neutrinos travel at the speed of light so the source is not moving. This means that the source is the nucleus of the carbon atom. Sorry, I was misled.
To not dismiss a particular type of reasoning as a ‘relic of a bygone age’ is more than mere nostalgia. In Bayesian reasoning (Bayes lived in the 1700s), a knowledge network can be read top to bottom to deduce effects, or bottom to top to infer causes. This doesn’t prove or ‘resurrect’ cause & effect, but it does produce darned useful models, even in quantum mechanics.
It is dangerous to assume that cause and effect can be derived from a model.
Models are not real, they’re attempts to approximate reality.
So when the climate models predict continued warming, and no warming occurs for a decade or more, we can safely dismiss the model as being inadequate.
The last decade shows trivial (if any) global average temperature increases:
http://tinyurl.com/7zwa2ne
In Science, theories make predictions.
In Science, theories are tested against their predictions.
When the predictions FAIL, theories are normally revised, re-evaluated, reconsidered, re-examined, recalculated, or just plain re-jected.
What forces are keeping the AGW alarmism theory from being seriously revised, if not merely those of Political Correctness?
So far, 2012 has been the warmest year the United States has ever seen, with the warmest spring and the second-warmest May since record-keeping began in 1895, the U.S. National Oceanic and Atmospheric Administration reported.
Read more: http://www.vancouversun.com/news/Climate+change+warmest+spring+record+says+NOAA/6751056/story.html#ixzz1xjDAIoQA
Look at the global data, not local weather.
It is supposed to be “global” warming, after all.
All four of the major global temperature anomaly datasets show that the temperature increases of the end of the 20th century have stalled in the 21st, despite continued unabated CO2 increases.
The paradigm of “CO2 caused all the observed warming” is running into present day problems in addition to the failure to account for the 1910-1940 warming and subsequent cooling.
Hadley:
http://www.cru.uea.ac.uk/cru/data/temperature/
NASA:
http://data.giss.nasa.gov/gistemp/graphs/
NOAA:
http://www.ncdc.noaa.gov/sotc/service/global/global-land-ocean-mntp-anom/201001-201012.gif
UAH satellite data:
http://www.drroyspencer.com/latest-global-temperatures/
Some two thirds of the supposed effects of CO2 have been attributed to it via positive feedbacks, primarily of H2O. While the hypothesis has some vague plausibility, it has as yet no substantive evidence in its favour.
In contrast the hypothesis that changes in cosmic ray flux, mediated largely by solar activity, cause changes in cloud formation rates has at least experimental evidence consistent with the hypothesis. I’m sure you’re aware of Jasper Kirkby’s (et al) continuing work at CERN determining the effects of changing cosmic rays on a test atmosphere.
Your interpratation of Hume is 180 degrees off the mark. If anything Hume is famous for denying that causation should be intrinsic to our physical laws and the natural of events themselves. Hume argued that all that really existed was a sequence of events and that causation was a notion we projected onto that sequence in some fashion. Exactly the point Hume was making was that just because these are practically useful and seemingly meaningful notions doesn’t mean we need to insert causation into natural laws.
The reason he goes into detail giving conditions for causation is to convince the readers who believed cause and effect were facts out there in the world that our use of the words could be explained without need to build causation into our physical laws. Maybe his analysis isn’t quite right but given that we use the words in a wide range of contexts quite successfully there has to be some reduction of the notions of cause and effect to space of events.
Also I think the logical positivists deserve more credit. Sure, they weren’t completely right but they were an overreaction to the spread of charismatic nonsense as an academic discipline in the guise of various psychoanalytic approaches to history or politics as well as philosophical marxism. I give the logical positivists credit for creating a viable alternative to continental philosophical rubbish, encouraging the study and occasional correction of scientific inference and incorporation of mathematical techniques into philosophy.
I’m afraid you’ve also seriously oversimplify Hume’s view. You can find the full 8 heuristics he gives to judge if one thing is the cause of another and it’s pretty clear he would not judge night to cause day because similar events such as darkening due to cloud cover or the months long night at the poles fail to provide appropriatly similar variation in effects.
However, I don’t think any of these extra considerations is even required if you read your second quote from Hume correctly. Obviously, he didn’t mean to define cause in terms of random folklore or prejudices so the sense that our mind might be drawn to vampires on seeing a pair of puncture marks. A much better interpretation would understand bringing our thought as making us think of the effect as more likely (other things being equal). That is I take him to be trying to get at the idea we would express in modern terminology as: for events of type A A to cause those of type B conditioning on the occurrence of an A event must, after controlling for all other observations (thus tossing out mere common causation), raise the probability of a B event.
To quote Hume:
there is no relation, which produces a stronger connexion in the fancy, and makes one idea more readily recall another, than the relation of cause and effect betwixt their objects.
Despite what you say, Hume gave cause and effect a special place.
I don’t know (but wouldn’t be surprised) if Hume felt that cause and effect had a special role to play in the study of science. However, my point stands regardless. Hume is famous for advocating a less central role of cause and effect in science than was accepted at the time (or even now amoung philosophers). I take redescribing cause and effect as mere epiphenomena of physical regularities to be relegating cause and effect to a myth in the sense I took you to be using the word above. Of course, this is totally compatible with believing that special attention should be paid to these definitions and they have a special *psychological* or *practical* role to play in the practice of science. Thinking about cause and effect could even be the most effective way of approaching the problem of describing physical laws even though they are a ‘myth’ in the sense that there is no objective fact out in the world about cause and effect.
Indeed, I would argue that even now they have a special role. Even though we may be able to formulate equivalent laws that take the form of restrictions on spatial arrangements or some other formulation rather than the familiar form of restrictions on future events ensured by facts about past events such formulations are decidedly less useful.
Only a small part of our interest in science arises from purely intellectual curiosity about our ability to find redundancies (constraints) on the collection of events across all space-time. Even most pure science is driven at some level by a desire to be able to predict or control events and that means formulating the laws in a manner that allows us to separate what we see as causes from what we see as effects (maybe a being whose time dimension corresponded to one of our space dimensions would define cause and effect differently but for us causes are the sort of things we can alter to change effects). Thus, even when our approach makes use of other ways of representing regularities in the world it still focuses on causal applications.
Most strikingly all of thermodynamics only makes sense as an investigation of cause and effect. The laws of thermodynamics aren’t entailed by the rules of fundamental physics as CPT tells us. The universe could just as well run in a fashion in which entropy decreased. Entropy increase in the direction the causes propogate to effects for the simple reason that entropy picks out a dimension along which we can remember the past but not the future.
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Perhaps I misunderstood you but this seems to be pretty much what you are saying. Cause and effect aren’t built into the fundamental laws of the universe but they nevertheless have a useful role to play in science and it’s practical applications.
Also I should add that causation is perfectly applicable to quantum mechanics.
Sure, we see indeterminism in QM when we make measurements but the wave functions evolve perfectly deterministically (absent some unlikely quantum gravity mechanism for collapse). Thus, all of our reasoning about causation can be applied virtually unchanged to the wavefunctions (which are the proper object of study in QM anyway…telling people that QM studies particles or classical waves but those particles can be in multiple places at the same time or any of this other nonsense generates excitement at the cost of confusion. It’s the wavefunctions (well the field states) that appear in our theories so that is what is out there.
The important thing are the observation. In quantum mechanics the observations are not deterministic. As I said in the post, in quantum mechanics, there is nothing that causes a radioactive atom to decay at one tome and not another.
“It is dangerous to assume that cause and effect can be derived from a model.”
agreed.
“Models are not real,”
agreed.
“they’re attempts to approximate reality.”
agr… wait a minute.
Some models are attempts to learn. Brewing up new ‘what if’ questions, designing ‘doable’ experiments, or even just testing/configuring new hardware/software in preparation for later models are all possible justifications. If accuracy of prediction was the only criterion for early dismissal of a model, we’d still be teaching Ptolemaic astronomy. Exploration and learning are not strict linear processes.
An example is the use of Bayesian modeling to work backward from RNA->protein translation when introns have scrambled the issue. Approximating nature is not the real goal. Evaluating probabilities on the way to reconstructing original DNA is.
Very nice post and very lively discsuision of the subject. I always thought that cause and effect is always a matter of logic rather than myth.