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Thought Contagion: How Belief Spreads through Society

Aaron Lynch
New York, NY: Basic Books
Cloth: ISBN 0-465-08466-4; Paper: ISBN 0-465-08467-2

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A response to Paul Marsden by
Aaron Lynch <http://www.mcs.net/~aaron>.

Cover of book

Marsden's (1999b) review of my book Thought Contagion: How Belief Spreads Through Society listed numerous supposed flaws in the text, but failed to mention the one real flaw most crucial to readers of JASSS. That flaw, imposed by standards of simplicity in the trade book market, was the complete omission of technical, mathematical and quantitative material I had published earlier and submitted as a pair of appendices. A serious gap in the coverage of the book arose from the fact that the mathematical population memetics analysis (Lynch 1991) could not be included even as an appendix. The system of non-linear, partial differentio-integral difference equations for host population as a function of time would have provided a good method of parameterisation for simulations of interest to JASSS readers. The definition of a "meme" as a "homoderivative mnemon" (memory item caused by prior instantiation of the same memory item) would also have lent a technical clarity that JASSS readers could utilise. Moreover, the non-metaphoric event diagrams used in that paper could have formed a useful conceptual framework from which to design memetic simulations. Yet Marsden has previously mislabeled the equations (republished in Lynch 1998) as "... arbitrary mathematical manipulations ..." and the event diagrams as "... laws of combination and permutation ..." (Marsden 1999a). So we should not be surprised that he has not flagged their absence as a serious flaw. The 1998 edition of this technical, mathematical and quantitative population memetics (Lynch 1998) even receives further negative commentary in Marsden's review of Thought Contagion.

Other aspects of Marsden's review demonstrate that by carefully choosing which sentences and sentence fragments to quote or misquote out of context, and how to mislabel them, one can make any book look totally silly. So I invite JASSS readers to read chapter 1 of Thought Contagion online and judge for themselves whether the book's opening is really as silly as Marsden makes it look.

While Marsden's review does mention topics covered in Thought Contagion, his portrayal of my analysis is misleading to say the least. For example, there really is a section on the evolution of memes pertaining to homosexuality (p. 79-84). In a nutshell, it says that adherents of the taboo out-procreated more tolerant people over the course of many generations in ancient times, leading to increased prevalence of the taboo. (This does not require anything like a perfect correlation between morality and behaviour, or a perfect child inculcation rate, but only enough to increase taboo prevalence by several percent per generation over hundreds of generations.) Then horizontal transmission kicked in as people maligned homosexuality to "prove" their adherence to the taboo. As the taboo becomes extremely widespread, most homosexuals live heterosexual lives, leading them to reproduce any genes involved. As these genes gain prevalence, the rate of taboo dropout increases. Gene carriers who have dropped the taboo are more sexually and socially motivated to spread acceptance of homosexuality than are non-gene carriers who drop the taboo. So the rising gene prevalence can lead to a self-sustained propagation of pro-gay memes. (Horizontal transmission again, contrary to Marsden's claim that I ignore this mode.) That, in turn, can lead to lower gene prevalence in the next generation, and even lower prevalence of pro-gay memes. All of this leads to potential fluctuations over long time spans. Incidentally, there is a brief mention of the way that beliefs about anal sex become involved with homosexuality taboos. Yet despite a multi-faceted discussion of homosexuality taboos, Marsden excerpts a sentence on anal sex and presents it as if I had offered it as the answer to the question "What memes deter homosexual behaviour?" He has thus taken a complex argument and misrepresented it as childishly silly. He uses a similar distorting approach in all of his other indented excerpts.

The "appendix" in which Marsden supposedly lists "Lynch's Seven Modes of Memetic Transmission" in the same indented format is not based on excerpts at all. There, the wording of each mode is Marsden's, and phrased so as make a mockery of what is actually said. Finding out what I actually said, however, is as easy as reading chapter 1 online. For example, it would have been simple for Marsden to quote me directly as saying "Any idea influencing its hosts to have more children than they would otherwise have exhibits quantity parental transmission." (p. 3) Instead, he misrepresents the label I give to a natural phenomenon as being an inane exhortation to "Have lots of children and use your position of authority to indoctrinate them and increase the prevalence of your beliefs." Marsden likewise misrepresents all of the other transmission modes, mostly as exhortations to the reader.

Under proselytic transmission Marsden even attributes to me (without page reference) a vague and incomplete statement that "A belief that spreads will spread ..." (ellipsis is Marsden's). This directly contradicts what the book actually says: "Proselytic thought contagion becomes self-limiting as host population growth diminishes the supply of nonhosts. Few nonhosts remain by the time the host population is a great majority since most have already converted by then. Without enough nonhosts, especially persuadable ones, the proselytizing cannot win many new adherents. This creates cycles in which successful proselytic movements lose momentum, setting the stage for renewed outbreaks of old movements and initial outbreaks of new movements" (p. 6). In other words, many beliefs that spread will therefore stop spreading or even go into decline.

In order to find Thought Contagion a "spectacular failure" in putting memetics on a more serious footing in the sciences, Marsden not only misrepresents what it says, but also demands that the book serve a far broader function than it claims to serve. In the first sentence of the preface, I state that the book "... introduces a new branch of science dealing with ideas that program for their own retransmission ..." (p. vii) That is, ideas that gain propagation by influencing or manipulating adherent's idea-propagating behaviours. It is not offered as a general theory of cultural evolution, nor a general theory of social contagion. Even within the subject area of memes, the focus is not on the field in general, but rather, on the small but important subclass of memes that play a particularly active role in causing their own retransmission. For example, in my discussion of how my work relates to that of Durham (1991), I state "Yet Durham admits that in special circumstances, memes can depart from the mainline rout to prevalence. Such 'special case' memes are the ones I call thought contagions". (p. 25)

Some take a very expansive definition of the word "meme" and envision "memetics" as covering almost all topics in social science and social philosophy, for instance whether the self is an illusion (Blackmore 1999). For them, Thought Contagion may indeed be a disappointment. Yet the scientific community is by no means united behind Blackmore's vision of a universal memetics, as exemplified by a scathing review in Nature (Coyne 1999). This leaves a valuable role for my own more modest and scientifically conservative agenda of demonstrating that there are a reasonable number of phenomena that really call out for the evolutionary replicator analysis of self-spreading brain-stored information. Like Rogers (1995), I narrow my focus to discuss only a subset of cultural evolutionary phenomena, and this does not call for a thorough survey of literature in the broader field as Marsden seems to imply.

Contrary to one of Marsden's misquotations, I do not claim that my brand of memetics is "the missing link" in the social sciences. The phrase "the missing link" does not appear anywhere in my book, and for good reason. Thought Contagion expressly emphasizes that memetics should not be taken as a replacement to existing social science. In the preface, it says "Thought contagion theory considers mainly the question of how ideas program for their own propagation, and the consequences for cultural evolution. This is an important and long overdue addition to social science, but it is hardly offered as a replacement for all existing social science" (p. ix). Thought contagion memetics is only called a missing link, and is absolutely never treated as the last or only "missing link" in the social sciences.

Attached to Marsden's false claim that I call my work "the missing link" comes another false assertion that my second chapter is presented as a "brief misrepresentation of the social sciences." The actual chapter title is "A Missing Link: Memetics and the Social Sciences." Not only does this contain the only use of the term "missing link" in the whole book, but it also clearly labels itself as something other than a survey. An honest reading of the chapter, however, reveals that it is presented as nothing more than an abbreviated overview of the relationship between thought contagion memetics to the social sciences.

As if distorting the overall purpose of the book and Chapter 2 were not enough, Marsden attempts to generate suspicion based on the 3% of that chapter given over to a discussion of "Memetics and Psychohistory". Says Marsden, "Fortunately, suspicion is likely to be aroused in even the most uninitiated reader when Lynch includes a discussion of the science fictional "psychohistory" in his brief misrepresentation of the various social sciences, in the process of claiming that his brand of memetics is 'the missing link.'" What he does not mention, however, is that the material actually emphasizes the dissimilarities between memetics and Asimov's popular science fiction. So I invite JASSS readers to see for themselves whether that discussion causes suspicion as Marsden suggests, or whether suspicion comes solely from the effect of Marsden's words on the uninitiated reader. To help JASSS readers decide where to place their suspicions, I copy the entire three short paragraphs alluding to "psychohistory" right here:

Memetics and Psychohistory

Some have likened memetic history to the science fiction account of a theory called "psychohistory" in Isaac Asimov's Foundation series. Although psychohistory did not inspire memetics, the two theories do have surprising similarities. Both theories concern how history unfolds, and both give more consideration to the cumulative behavior of great masses than to the actions of special individuals. Both theories can cover hundreds of generations, and both can be translated into quantitative, mathematical equations. Like psychohistory, the memetic equations can even predict "future history" given some well-measured parameters and starting conditions.

Yet the analogies start to fade from that point on. In the science fiction story, a psychohistorian can predict most of society's behavior far into the future and quite precisely. Thought contagion theory mainly considers a special subclass of ideological behaviors, and just measuring the variables can raise serious practical challenges. The quantitative translation of the theory also leads to nonlinear equations, which mathematicians and meteorologists now see as a bane to long-range forecasting.

Thought contagion memetics might never amount to the stuff of science fiction, but it can make an important contribution to the understanding of history and the human condition. (Thought Contagion, p. 38-39)

There is in fact so much misrepresentation, distortion, misleading assertion and poor scholarship in Marsden's review that it would take an unreasonably long line-by-line critique to expose all of it. Instead, I caution anyone who reads any part of Marsden's review to read my own work directly and see what it really says, no matter how innocent, innocuous or plausible Marsden's statements look. I also invite readers to consider the possibility that if Marsden needed so much misrepresentation in order to produce his negative review, Thought Contagion may actually be quite good. Indeed, contrary to Marsden's statement that there is not "the slightest risk that anybody could possibly take it seriously," Thought Contagion has endorsements from Richard Dawkins and Douglas Hofstadter on its cover.

It is true that the full title of the book is "Thought Contagion: How Belief Spreads Through Society: The New Science of Memes." While this may seem to claim a far wider territory than the book actually covers, I should explain that the subtitle "How Belief Spreads Through Society" is only intended to identify the subject area in general terms to people who have never heard the word "meme." The line "The New Science of Memes" is only intended to place the book in the subject area of memetics for those who have already heard of memes. Yet the body of the book makes clear that thought contagion memetics is a limited subdomain of memetics generally. (p. 25) That may trouble those readers who hold a grand vision of memetics as accomplishing everything for culture that Darwinism did for biology, but I remain committed predominantly to the specialised realm of thought contagion memetics.

As Marsden asserts, Thought Contagion is indeed filled with hypotheses awaiting empirical investigation and the book warns the reader of this in advance (p. viii-ix). In the preface, I express the hope that publishing hypotheses will stimulate the research needed to test them. Likewise, the publication of hypotheses about evolution, biological contagion, quarks and other phenomena has historically played an essential part in stimulating empirical studies.

In fields ranging from biology to physics, works written for non-specialists must often forego the most technical definitions of terms to achieve broader accessibility. Hence, Thought Contagion does not contain my most formal and precise definition of the word "meme." Yet Marsden, despite knowing my formal technical definition, seizes upon the limitations of a book written for general audiences to suggest an underlying imprecision and confusion in my use of the word. For instance, in his eighth paragraph, he refers without page reference to my statement "Because the information resides more at the community than the individual level, ownership qualifies as a kind of 'transcendent meme,' but not as an ordinary meme" (p. 19) to persuade readers that they should be "confused." In keeping with his overall pattern of presentation, Marsden distorts what I said in a way that makes it look ridiculous: "transcendent meme" in my book becomes "transcendental meme" (emphasis added) in Marsden's review and out of context. (In context, the word "transcendent" is not the least bit mysterious: it simply indicates that ownership resides not in the individual, but in social entities such as communities and states that transcend the individual.) Marsden then goes on to announce that he was "no more enlightened" by reading my technical paper "Units, Events, and Dynamics in Memetic Evolution" (Lynch 1998). All of these suggestions of confusion, mystery and unenlightening exposition on my part calls for a presentation of the technical definition of "meme" from Lynch (1998):

"MEME: A memory item, or portion of an organism's neurally-stored information, identified using the abstraction system of the observer, whose instantiation depended critically on causation by prior instantiation of the same memory item in one or more other organisms' nervous systems. ('Sameness' of memory items is determined with respect to the above-mentioned abstraction system of the observer.)"

Removing the philosophy of science about abstractions (explained in the paper), this becomes more simply:

"MEME: A memory item, or portion of an organism's neurally-stored information, whose occurrence depended critically on causation by prior occurrence of the same memory item in one or more other organisms' nervous systems."

This definition identifies the minimum conditions needed to achieve the recursive process (or algorithm) that forms the basis of evolution by natural selection in interpersonally transmitted brain-stored information. It becomes the basis of transmission event diagrams and differential equations (Lynch 1998) useful in developing computer simulations of the meme transmission patterns discussed in the book Thought Contagion.

Filled as it is with misinformation about both the book Thought Contagion and the technical memetics paper cited in its preface, Marsden (1999b) fails spectacularly as a book review. What Marsden has "reviewed," is, in effect, his own series of misrepresentations. Those looking for fresh methods and topics in quantitative social simulation would therefore do better to ignore Marsden's contentious, misleading "review" and read Thought Contagion and its supporting technical papers directly.

* References

BLACKMORE S. 1999. The Meme Machine, Oxford University Press, Oxford. [JASSS review.]

COYNE J. 1999. The Self-Centred Meme: A Review of The Meme Machine by Susan Blackmore, Nature, 398:767.

DURHAM W. 1991. Coevolution: Genes, Culture, and Human Diversity, Stanford University Press, Stanford, CA.

LYNCH A. 1991. Thought Contagion as Abstract Evolution, Journal of Ideas, 2:3-10. [Scanned reprint available online.]

LYNCH A. 1996. Thought Contagion: How Belief Spreads Through Society: The New Science of Memes, Basic Books, New York, NY. [Chapter 1 available online.]

LYNCH A. 1998. Units, Events and Dynamics in Memetic Evolution, Journal of Memetics - Evolutionary Models of Information Transmission, 2, <http://www.cpm.mmu.ac.uk/jom-emit/1998/vol2/lynch_a.html>.

MARSDEN P. 1999a. A Strategy for Memetics: Memes as Strategies, Journal of Memetics - Evolutionary Models of Information Transmission, 3, <http://www.cpm.mmu.ac.uk/jom-emit/1999/vol3/marsden_p.html>.

MARSDEN P. 1999b. Review of Thought Contagion: How Belief Spreads Through Society by Aaron Lynch, Journal of Artificial Societies and Social Simulation, 2, <https://www.jasss.org/2/2/review4.html>.

ROGERS E. M. 1995. Diffusion of Innovations, fourth edition, The Free Press, New York, NY.

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