Saturday, March 24, 2012

Smart Immigration Policy

Almost everyone is at least a little suspicious of out group members, so it should come as no surprise that most citizens view foreigners who want to live and work in their country with suspicion. Immigrants tend to be blamed for many negative things. They are accused of taking away jobs that citizens believe should be reserved for them and quite a few countries have laws saying a company can only employ a foreign national if they can show that a citizen could not be found to fill. The presence of foreign labor is frequently protested when labor markets are tight and in some countries this has reached the point of violence and mass displacement of immigrants. Immigrants are disproportionately blamed for crime. Some think immigrants come to live off welfare systems at the expense of citizens. Still others see immigrants as a threat to national culture e.g. Muslims are frequently seen as threat to countries with a Christian or secular history, and no doubt visa versa. Then there is outright racism or ethnocentrism.

To be fair suspicion and hostility aren’t the only reactions to immigrants. Some do view them positively. However on balance feelings are negative. So much so that between half and two thirds of the adult population of the USA wish to see immigration reduced from current levels, and only 5-10% wish to see it increased.

Before discussing empirical findings on the various purported pros and cons of immigration, and various intellectual arguments around it, I want to explore what intelligent opinion has to say about the issue.

The General Social Survey has a number of questions around the possible effects of immigrants. For each alternative on each question I tabled the percentage of public support and a Smart Vote score. The Smart Vote score is a measure of how much and in which direction IQ variations are related to an opinion. It is calculated as follows.

I calculate the ratio of the probability that the smartest and dullest IQ groups will support an alternative i.e. p(IQ>116)*(1-p(IQ<85))/((1-p(IQ>116))*p(IQ<85)) – call this the extreme ratio. Next I calculate the same for the intermediate IQ ranges i.e. p(IQ 100-115)*(1-p(IQ 85-99))/((1-p(IQ 100-115))*p(IQ 85-99)) – call this the intermediate ratio.

The Smart Vote score is 100*√((3*extreme ratio + intermediate ratio)/4)

I restricted the analysis to white opinion only because race is likely to be a strong confounding factor regarding immigration.

The table can be seen below.

Overall it seems more intelligent opinion thinks immigrants are good for America and that they contribute to improving America and making it more open. More intelligent opinion denies that immigrants make things bad. The Smart Vote is against immigrants increasing crime, taking away local jobs or undermining national unity. Finally more intelligent opinion is that there a small but non-zero chance that immigrants lead to economic growth. In short, the more intelligent the person the more likely they are to think that immigrants are not bad but good for America. The general public however tends to think unintelligently on immigration taking jobs away and undermining national unity.

In line with this more intelligent opinion is also in favor of treating immigrants better. The table below shows that more intelligent opinion is in favor of solid rights for immigrants, and that it doesn’t think immigrants are too demanding about it. More intelligent opinion is also in favor of helping immigrants overcome bias and extending government assistance if needed and doesn’t think the government spends too much on them.

On the other hand more intelligent opinion is against illegal immigrants getting work permits and access to public education. However, intelligent opinion seems neutral on whether the US should exclude illegal immigrants altogether. Finally, should the USA let in more or fewer immigrants? In spite of intelligent opinion regarding immigrants as a good thing generally this doesn’t translate into advocating letting in more of them. More intelligent opinion seems to think current immigration rates are close to ideal. Overall, more intelligent opinion is for assisting legal immigrants to overcome problems and bias, and perhaps granting them equal rights, but for keeping the rate of immigration close to the current rate. The majority of the general public, however, seem to lean toward the less intelligent choice of being unhelpful to immigrants and toward greater exclusion of them – both legal and illegal.

Before we accept this picture the issue of special interests associated with intelligence need to be addressed. The following table is a summary of the multiple regression results on all the questions dealt with above, controlling for education, income, gender, age and ideology. Race is already controlled for because all results apply to white opinion only. The table shows the significance level achieved and the direction of the relationship.
** Means a significance level > 5% but less than 10%.

Note that the more intelligent view i.e. the Smart Vote, that immigration is good rather than bad, is confirmed. On the other hand it seems the seemingly intelligent view that legal immigrants should be assisted and granted equal rights, or that illegal immigrants not be given access to work permits or public education, is probably special interests speaking rather than intelligent opinion per se. The intelligent opinion that current rates of legal immigration are about right is confirmed.

It seems that increased education in the US leads to a strong pro immigrant attitude across the board. The interests associated with gender or income differences don’t seem to matter much. A Conservative outlook is associated with believing immigrants lead to crime and unemployment, with the view that they shouldn’t be assisted or given more rights and the view that illegal immigrants should be totally excluded. Liberals tend to hold the opposite view. Surprisingly, at least to me, is that while older people tend to reject giving immigrants greater rights or helping them they are more inclined to think immigrants are good rather than bad for America than are younger people.

To summarize – the smartest view on immigrants is that they are good and not bad for America, and that the current rate of legal immigration is about right. Whether to help them or give them greater rights is unanswered. The general public’s view however is that immigrants do have a few bad effects and leans towards reducing the rate of immigration generally.

Why should we restrict immigration?

So much for the arrow of the Smart Vote in the absence of evidence and argument, but what does the evidence say? Here are some of the findings.
The labor force participation rate among immigrants is higher than that of the native born and higher still among illegal immigrants1.

Immigrants tend to self select states with lower social or welfare spending especially illegal immigrants who have no reason to favor welfare states since they aren’t eligible. Immigrants clearly aren’t moving in order to live off American welfare1.

The fiscal effects of illegal immigrants was very slightly negative – they consumed 24.4% more in services than they paid in taxes - but the economic effects are very strongly positive – over 35 times the fiscal loss!2

Since people don’t like paying for people different from themselves immigration will undermine welfare spending and not increase it.

Low skilled immigrant labor frees high skilled natives to do more productive work thereby increasing the growth rate.3

Low skilled immigrants e.g. those whose comparative advantage is manual labor, open up slightly higher level coordination and integration jobs for low skilled natives who speak English, and improves their pay.3

Immigration keeps America young and mostly working – good for growth and maintaining the social security system.4

Immigrants have lower per capita crime rates.

Border enforcement is costly – much more so than the fiscal costs incurred by illegal immigrants.

What we gleaned from intelligent opinion alone is correct – immigration is good and not bad for America.

Why should they be treated as criminals for wanting to do an honest day’s work? Why should a free transaction between a US citizen and a foreigner be banned? Free trade is almost an article of faith among economists of all ideologies so why not free trade in labor? The most convincing arguments I’ve seen for open immigration are those of Bryan Caplan – professor of economics at George Mason University. I lifted the following verbatim from his blog EconLog.

Many libertarians would condemn [the American government's treatment of immigrants] as "inexcusable." I rest my argument on a weaker premise: whether or not the facts are "inexcusable," they do require an excuse. On the surface, it seems wrong to prohibit voluntary exchange between natives and foreigners. Proponents of immigration restrictions have to show why, moral appearances notwithstanding, immigration restrictions are morally justified.

They fail to do so. Immigration restrictions are not necessary to protect American workers. Most Americans benefit from immigration, and the losers don't lose much. Immigration restrictions are not necessary to protect American taxpayers. Researchers disagree about whether the fiscal effects of immigration are positive or negative, but they agree that the fiscal effects are small. Immigration restrictions are not necessary to protect American culture. Immigrants make our culture better--and their children learn fluent English. Immigration restrictions are not necessary to protect American liberty. Immigrants have low voter turnout and accept our political status quo by default. By increasing diversity, they undermine native support for the welfare state. And on one important issue--immigration itself--immigrants are much more pro-liberty than natives.

Even if all these empirical claims are wrong, though, immigration restrictions would remain morally impermissible. Why? Because there are cheaper and more humane solutions for each and every complaint. If immigrants hurt American workers, we can charge immigrants higher taxes or admission fees, and use the revenue to compensate the losers. If immigrants burden American taxpayers, we can make immigrants ineligible for benefits. If immigrants hurt American culture, we can impose tests of English fluency and cultural literacy. If immigrants hurt American liberty, we can refuse to give them the right to vote. Whatever your complaint happens to be, immigration restrictions are a needlessly draconian remedy.

Elsewhere Caplan argues that immigration is fantastically beneficial to immigrants themselves. Unskilled labor from the developing world earn on average 10 times more in the developed world as they would in their country of origin, and that open immigration globally would double global GDP. Open immigration is by far the best anti-poverty measure in existence.

Mat Yglesias on Moneybox (part of Slate) – another superb commentator but from a different ideological camp to Caplan – argues that immigration should lead to improved labor conditions in the country of origin, because good workers would vote with their feet and employers would have to increase wages and improve working conditions to compete. He has also argued that immigrants (including illegal immigrants) will need houses, food, medicine, transport, clothing, entertainment, etc which means more business for suppliers of those things and therefore more jobs for locals.

Intelligent opinion is that a policy of increasingly restricting immigration is likely to be stupid and badly thought through. The arguments and evidence above strongly confirm that view. I don’t know why the Smart Vote is not more frankly for open immigration.


1. Immigration and the Welfare State by Daniel T Griswold
2. Immigration and Economic Growth by Gordon Hanson
3. Immigration, Labor Markets and Productivity by Giovanni Peri
4. America’s Demographic Future by Joel Kotkin & Erika Ozuna
5. Why Should We Restrict Immigration? by Bryan Caplan
6. Economics and Immigration: Trillion Dollar Bills on the Sidewalk? by Michael A Clemens

Friday, March 16, 2012

Chess, intelligence and winning arguments


We have all had arguments. Occasionally these reach an agreed upon conclusion but usually the parties involved either agree to disagree or end up thinking the other party hopelessly stupid, ignorant or irrationally stubborn. Very rarely do people consider the possibility that it is they who are ignorant, stupid, irrational or stubborn even when they have good reason to believe that the other party is at least as intelligent or educated as themselves.

Sometimes the argument was about something factual where the facts could be easily checked e.g. who won a certain football match in 1966.

Sometimes the facts aren’t so easily checked because they are difficult to understand but the problem is clear and objective. One famous example is the Monty Hall dilemma. In a certain game show a contestant is presented with three doors, behind one of which is a really desirable main prize and behind the other two are booby prizes. The contestant is asked to choose the door he thinks the main prize is behind. The game show host, who knows where the prize is, then opens a booby prize door. He can do that even if you picked the main prize door. The contestant is now offered the chance to change his choice to the other closed door. The question is – should he? The correct answer is that he should because it would double his chances of winning the main prize. This fact proved so hard to grasp that only 8% of the laymen and 35% of academics who tried it, got it right initially. Many of them damned Marilyn vos Savant for misleading the public with her answer in her Parade column Ask Marilyn. Among those academics getting it wrong, were a fair number of senior professional mathematicians and statisticians, including the great Paul Erdos. After a great deal of explanation, the proportion of people who accept the correct answer increased to 56% of laymen and 71% of academics. The figure is more like 97-100% for those who carried out an experiment or simulation, so in essence a large proportion of those approaching the problem through pure logic continue to fail to grasp it.

Sometimes the facts aren’t as mathematical or logical as the Monty Hall solution. Each party to the argument appeals to ‘facts’ which the other party disputes. The disputed facts could be anything from the validity of the theory underlying a phenomenon, or the empirical results supposedly shedding light on the topic. A good example would be the debate among economists about the causes of the most recent US recession and the most useful way out of it. On one side are those who think the solution is less government spending to reduce deficits, and simply leaving the economy to painfully sort out major structural mal-investments and imbalances. They believe intervention is likely to create worse problems later. The other side says aggregate demand is the problem and that the recession can and should be fixed via some kind of fiscal and monetary intervention. This side believes intervention will make things better, not worse, in both the long and short term. Both sides claim that the other side’s view has been thoroughly discredited by empirical events in the past, and will point to current events ‘obviously’ supporting their expectations, or when they haven’t will issue dire warnings that it will, soon. A similarly insoluble argument is being had around the ‘facts’ of global warming.

Sometimes the arguments boil down to differences in values. For example, what tastes better chocolate or vanilla ice cream, or who is prettier Jane or Mary? In these cases there isn’t really a correct answer – even when a large majority favors a particular alternative. Values also have a strong way of influencing what people accept as evidence or indeed what they perceive at all.

The unreasonableness of continuing disagreement

The interesting thing is that when the disagreement isn’t a pure values difference it should always be possible to reach agreement. Robert Aumann, a Nobel winning game theorist (who I’ve had the pleasure of chatting to) proved that under conditions of common knowledge it isn’t possible to agree to disagree – even when the parties start with completely different information, facts and theories. In a simplified format it goes like this. Party A says the answer is X. Party B, who considers the answer to be Y, hears this and, if rational, will think “A must either have access to evidence that I don’t or doesn’t have access to some evidence that I do.” Under the notion of evidence I include not only facts but also the reasoning process. B may say that “Notwithstanding the possibility that I may have missed evidence I am still very confident in the evidence that I have so I will say I think the answer is Y”. A now hears B’s answer and goes through a similar chain of reasoning. He thinks “Gosh B has evidence he is so confident about that exposure to the knowledge that I have different evidence hasn’t shaken him. He must think his evidence is particularly strong. I should take that into account when evaluating my own evidence.” At this point A could decide he isn’t all that confident in his own evidence, and concede the argument to B. Alternatively he could decide that in spite of B’s confidence he still considers his own evidence to be persuasive, and re-affirm that he thinks the answer is X.

The ball now passes back to B, who now faced with A’s continued confidence in his evidence, even after making allowances for B’s confidence in his own evidence, must upgrade his view of the strength of A’s evidence relative to his own. He must then decide whether he is still thinks his evidence is strong enough to carry the day. He can decide “No it isn’t”, and concede the argument to A, or “Yes it is” and say he still considers Y to be correct. The process goes on until one of the parties concedes. At any point either party’s actual evidence can, and probably will, be shared and explained. Some readers may recognize this as an iterative Bayesian process. Others have extended Aumann’s analysis, and have shown that the process won’t go to infinity and should come to a conclusion in a reasonable number of iterations. The upshot of this is that if an argument doesn’t result in an agreement, at least one of the parties involved is being irrational or dishonest.

The rest of the article makes the unrealistic assumption that people will be rational and honest when arguing.

IQ and relative correctness

Item response theory connects a latent trait e.g. intelligence or IQ, with the probability getting a particular item in a test correct. Typically they look like this.

The formula producing these lines is


The “a” coefficient tells one how steeply the probability rises as IQ rises i.e. how much solving the item depends on ability as measured by IQ versus how much the solution depends on uncertainty and luck. The “b” coefficient tells one the difficulty level of the item.

Suppose we select two IQ levels and compare the probabilities of a correct answer for each IQ level. With a bit of arithmetic we can show that the ratio of

p(IQ2)/p(IQ1)=exp(a*( IQ2 - IQ1)).

Suppose two people with IQs at level 1 and 2 respectively disagree about the answer. In effect they argue about it. Then the probability of person with being right in the event of a disagreement is

p(2 is right) = p(2)*(1-p(1))/((p(2)*(1-p(1)) + p(1)*(1-p(2))). Similarly for p(1 is right).

More arithmetic gives

p(2 is right)/p(1 is right) = exp(a*( IQ2 - IQ1)) too.

Therefore, when two people argue over the correctness of something, the probability of who is right is determined by the difference between their respective abilities and the degree to which solving that problem actually depends on ability. The difficulty of the item is irrelevant.

A chess diversion

Chess’s ELO rating system uses a similar method to calculate the probability of a player winning, but use base 10 rather than base e. So according to the ELO rating system used by FIDA

p(player a)/p(player b)=10**(Ra – Rb)/400 (which obviously = exp(a*( IQ2 - IQ1)).)
- where Ra is the ELO rating of player a.

This means that if the player’s ratings differ by 200 points then the highest ranked player should take roughly 3 out of every 4 wins between them. A ratings difference of 400 points means 10 wins for the highest ranked player for every win for the lower ranked player. The median rating for members of the US Chess Federation was 657 and rating of 1000 is regarded as a bright beginner. International Grandmasters typically rate 2500+, and the very best players have ratings slightly over 2800. To give you an idea of the differences in skill, consider that if the very best were to play an average player the ratio of wins is likely to be 227772 to 1. The difference between a grandmaster and a good beginner would be 5623 to 1.

The identities above mean that we can easily convert an IQ difference into an equivalent ELO ratings difference, using the following formula

Ratings difference = 173.7178*a*(IQ difference)
- “a” is the coefficient telling us how much the item depends on IQ for its solution.

I looked at the distribution of FIDA ratings in order to convert them to an IQ metric. For example, about 2% of chess players have ratings as 2300 or higher and 0.02% have ratings over 2700. If IQs are normally distributed, with an SD of 16, then these ELO ratings would correspond to 132 and 157 on the IQ scale. Note this doesn’t mean that chess players with a rating of 2700 will actually have an average IQ of 157 – it’s just a different way of specifying the same thing e.g. like a change from the Imperial to the Metric system.

I did however find a study (1) that allowed me to map real IQs onto chess ratings in experienced players. The equation is

Chess rating = 18.75*IQ – 275.

It turns out that the expected real IQs are very close to the IQ metric I calculated from the ratings distribution. (Note that the equation I developed is quite different from the one hypothesized by Jonathan Levitt (3) i.e. Rating = 10*IQ + 1000.) One should also be aware that the equation gives an average IQ – the actual IQs vary quite a bit around the expected figure. For example, the authors show that threshold effects exist and that the minimum IQ needed to achieve a rating of 2000 is around 85-90. This is 30-35 IQ points lower than the expected IQ. Also from his peak rating Garry Kasparov’s expected IQ is 167 (and wild claims of 180+ have been made) but his actual IQ was measured at 135 (in a test sponsored by Stern magazine), some 32 IQ points lower.

I suppose one could derive a rule that the minimum IQ required for a peak rating is some 32 IQ points (or 2 SDs) below the expected IQ. Alternatively, it means that if you have a combination of memory and industry in line with elite professional chess players, your peak rating is likely to be 600 ELO points higher than it would be if you were like an average chess player in these respects. Your chances of winning could be as much as 31.6 fold higher than your IQ suggests – or that much lower. That says something about the relative value of focused application.

Assuming that the distribution of combined effort and memory is symmetrical, it also means that a 64 IQ point advantage can not be overcome - even if the brighter player is also among the very laziest with a bad memory, and the less intelligent player has a superb memory and is among the most dedicated.

Even after accounting for IQ and work the predicted ratings are still a little fuzzy so perhaps random factors play a role too.

IQ and ELO rating differences in other domains

Here I look at converting the effect of IQ gaps to ELO rating differences, across a variety of domains

Let’s get back to the IQ to ELO rating conversion. Recall that the equation is

Ratings difference = 173.7178*a*(IQ difference).

All that remains is to find “a” for everything we are interesting in.

Clear Objective problems

The obvious place to start is IQ test items. The “a” coefficient for more fuzzy IQ test items tend to be around 0.046, and around 0.086 for really efficient IQ test items. That means that for fuzzy items each additional IQ point is worth 8 ELO points, and it’s worth 15 ELO points for good IQ items. If these items are used in a weird tournament where players compete to solve puzzles instead of play games, and we set the bar at a 3 to 1 win ratio (a 200 point ELO rating difference), then fuzzy items will require a 25 point IQ gap, and efficient items a 13-14 point IQ gap.

Physics mastery

Using information from an article by Steve Hsu (2) I worked out that a 3 fold advantage at “winning” at a physics exam – where a ‘win’ is an A in the exam when your opponent failed to get an A – requires an IQ gap of 12 points. If however a win is defined as a 3.5 GPA (where your opponent fails to attain this), then a mere 6 IQ points will provide a 3 fold advantage.


We could view cops and killers as being involved in a grim contest. In the USA around 65% of all murders are solved. That converts to an average “murder” ELO rating difference between police and murderers of 108 ELO points. It is also known that the mean IQs of murderers and policemen are 87 and 102, respectively. So successfully solving murders is a puzzle then the “a” coefficient is 0.041, and each IQ point difference is worth 7.2 ELO points. A 3 fold advantage could be had with a 28 point gap between cops and killers. In other words some 31% of outstanding murders could be solved if the USA selected its policemen to have an average IQ of 125 i.e. to be as smart as an average lawyer. I’m not sure if that’s worth it but maybe some cost benefit analysis would help. Such an analysis would have to take into account the drop in murder rates (with a life currently being valued at $2 million) due to the greater odds of being caught, and the opportunity cost of taking professional level IQs out of the pool for other professions, where they might be even more productive.

Controversial issues

Finally we get back to real arguments – disagreements over controversial topics. According to my Smart Vote concept (see, if proportionally more smart people systematically favor an alternative then that alternative is likely to be correct or better. Using that definition of “correct”, and information in the General Social Survey, I calculated the “a” coefficients and ELO to IQ ratios etc for a few controversial questions. Typically it would take an IQ difference of 30-50 points to gain a 3 fold advantage in a rational argument.

Tasks with a high level of uncertainty

For comparison I looked at an intellectual game that includes a large element of chance – backgammon. A rating equation gives

p(player a)/p(player b) = 10**Rating diff/2000

for individual games. The difference from chess is that it divides the rating difference by 2000 instead of 400. It would take the result of a string of 21-22 games to provide the same test of relative skill as does a single game of chess. Controversial questions are less fuzzy, less uncertain, or more tractable to intelligence, than backgammon. If people ‘played’ a series of arguments over controversial questions instead of a series of backgammon games, then it would take maybe 5-6 such arguments to provide the same test of relative skill/wisdom in arguments, as a single game does in chess.

A summary table

Some meaningful IQ or ELO rating differences

Some research shows that friends and spouses have an average IQ difference of 12 points, that for IQ differences less than 20 points a reciprocal intellectual relationship is the rule, for IQ differences between 20-30 points the intellectual relationship tends to be one way, and that IQ differences greater than 30 points tend to create real barriers to communication.

An IQ gap of 12 points implies a roughly 67-72% chance of winning an argument over a clear objective issue, like verbal or math problems, and close to a 57-61% chance of winning an argument over a controversial question. A 30 point IQ gap implies an 87-91% chance of winning a verbal/math item argument, and a 63-67% chance of winning an argument over controversial issues. It seems as though there is a very fine line between intimacy and incomprehension on controversial issues (a mere 6% difference) but a fair gap on more objective issues (a 20% difference).

Perhaps it isn’t so much the IQ gap that matters to people, as the proportion of differences of opinion they win or lose i.e. the ELO rating difference. That in turn depends on the balance of clear objective, uncertain, and controversial issues in their disagreements. In general however, it seems that people don’t like to lose more than 2 in 3 disagreements, and when they lose more than 3 in 4 of them they feel like they aren’t on the same planet anymore. Those proportions correspond to ELO ratings differences of 100 and 200 respectively. An ELO rating difference of less than 100 feels tolerable and reciprocal while a difference of more than 200 feels unfair or unbalanced. If that theory is right, when most of the issues are fuzzy or uncertain the larger IQ differences should occur between friends and spouses, but when they are mostly clear objective issues then those IQ differences will be smaller.


1. Individual differences in chess expertise: A psychometric investigation. Roland H Grabner, Elsbeth Stern & Aljoscha C Neubauer. Acta psychological (2006) but I got it from
2. Non-linear psychometric Thresholds for Physics and Mathematics. Steven D.H. Hsu & James Shombert.
3. Genius in Chess. Jonathan Levitt.

Sunday, March 4, 2012

Pornography - an intelligent view


With the advent of the internet, and high tech phones, pornography became significantly easier to access and the porn industry has grown exponentially. Currently in the United States the pornographic film industry is centered in the San Fernando Valley of Los Angeles, with an estimated 200 production companies in the region employing as many as 1,500 performers, making up to 11,000 films and estimated to earn as much as $13 billion a year. This is believed to be larger than Hollywood.

So pornography is popular, but some say that pornography has a variety of harmful effects, which argues for it being illegal.


The sociological objection is that pornography decreased respect for long-term, monogamous relationships, and attenuates a desire for procreation. Pornography can “potentially undermine the traditional values that favor marriage, family, and children”, and that it depicts sexuality in a way which is not connected to "emotional attachment, of kindness, of caring, and especially not of continuance of the relationship, as such continuance would translate into responsibilities"

The religious/conservative objection is similar to the sociological objection. They argue that this industry undermines the family and leads to the moral breakdown of society. They say that it is amoral, weakens family values, and is contrary to the religion's teachings and human dignity.

Some feminists argue that it is an industry which exploits women and which is complicit in violence against women, both in its production (where they charge that abuse and exploitation of women performing in pornography is rampant) and in its consumption (where they charge that pornography eroticizes the domination, humiliation, and coercion of women, and reinforces sexual and cultural attitudes that are complicit in rape and sexual harassment). They charge that pornography contributes to the male-centered objectification of women and thus to sexism.

Other objections are that the sex industry is sometimes connected to criminal activities, such as human trafficking, illegal immigration, drug abuse, and exploitation of children (child pornography, child prostitution). However these effects are related not so much to pornography as to prostitution.

How valid are these criticisms?

The Evidence

I will only address the consumption issue, not the criticisms around its production.

Firstly (using the General Social Survey) I found no relationship between being pro the legality of porn, or propensity to watch porn, and pro social behaviors e.g. volunteer work, blood donation, etc.

We can dismiss the feminist (and sociological) charges of porn increasing sexual violence and leading to sexism. The USA, Sweden, Germany, Netherlands (2) and Japan were just some of the countries that suddenly went from no legal pornography to quite widespread availability and consumption of it. These studies all found that greater availability of, and exposure to, pornography does not increase the rate of sexual assaults on women, and probably decreases it (3). Japanese porn is quite frequently violent and yet even there rape decreased from an already very low base. It’s interesting that an increase in porn exposure decreases sexual violence only, and has no effect on other crime. Economists would put this down to a substitution effect.

Several countries have sex offender registers – mainly of pedophiles. A wide variety of professions are represented on these registers. Members of professions that supposedly promote morality e.g. clerics or teachers, are quite common on it yet conspicuously absent from such registers are men who have worked in the porn industry.

This study (1) found no relationship between the frequency of x-rated film viewing and attitudes toward women or feminism. From the GSS (controlling for IQ, education, income, age, race and ideology) I found that those who are pro the legality of porn are less likely to support traditional female roles, more likely to be against preferential treatment of either gender, and to find woman’s rights issues more frequently salient. Although I found that women’s rights issues are less salient to male watchers, and female watchers are less likely to think women should work, I also found that watching porn is unrelated to negative attitudes toward women and feminism.

In short exposure to and tolerance of pornography does not cause anti-social behavior (and may even reduce it in relation to sex) and does not get in the way of pro social behavior either.

The sociological and religious charge that pornography undermines monogamy and family values does however receive support. From GSS (and controlling for IQ, education, income, age, race and ideology) I found that men who are pro legalizing porn are less likely to marry and are more pro cohabitation. There was no such association for women. A higher propensity to watch porn movies is also associated with a lesser likelihood of marrying but is unrelated to cohabitation attitudes - in both men and women. So a pro porn attitude is consistent with a reduced respect for marriage.

Both genders also tend to have fewer kids in marriage, if they are pro the legalizing of porn. However, for men, a higher propensity to watch porn movies is associated with having MORE children within marriage. Note that pro legal porn attitudes and porn movie viewership is not associated with having children out of wedlock – for men its associated with a lower chance of that happening – so porn doesn’t lead to that kind of irresponsible behavior.

Possibly part of this general pattern, I found that both being pro the legality of porn and watching porn are related to lower voting rates in general elections.

I found no relationship to a variety of ‘family values’ type questions e.g. importance of family, or to the value of relationships and friendship.

Being pro the legality of porn, and porn viewing, are associated with unhappiness with the family or marriage – especially for men. Those who are pro porn also tend to have a greater number of sexual partners and are more likely to have a sexual affair. This supports the 1984 and 1988 discoveries of Dolf Zillman and Jennings Bryant (4) that the effects of repeated exposure to standard, non-violent, commonly available pornography includes: increased callousness toward women; distorted perceptions about sexuality; devaluation of the importance of monogamy; decreased satisfaction with partner’s sexual performance, affection, and appearance; doubts about the value of marriage; and decreased desire to have children. Later research studies further confirm their findings.


I’ve already mentioned that exposure to porn doesn’t increase anti-social behavior or reduce pro-social behavior. However it does have a clear effect on satisfaction with relationship institutions and personal relationships. It can make a person think that what they have is poor in comparison. Naturally they’ll be unhappy if they think what they have is wrong, or can’t be improved upon. Some things can’t be improved upon, but in principle others can. I imagine it’s mostly those things possible in principle but unlikely in practice, that makes porn viewers especially unhappy.

Typically at this point the therapist says “therefore stop watching porn and learn to be happy with what you have”. The assumption here is that the solution to unhappiness always lies in going back to the pre-shock situation. While this may sometimes be the best option it is not always and necessarily the best option. Sometimes embracing the shock will not only solve the unhappiness but raise the relationship to a new high. For example what if the other partner comes to the party and is willing to try some of the pornographic possibilities? There are some findings that viewing porn together as a couple can provide some shared excitement and adventure, and lead to a more closely bonded and satisfactory relationship. Isn’t that a better result than what the therapist had in mind?

Suppose we divide people into 4 groups – don’t watch porn & think porn should be illegal to all, have watched or seen porn & think porn should be illegal to all, don’t watch porn but think it shouldn’t be illegal to all, and watch porn & think it shouldn’t be illegal to all. Suppose further that the men and women marry randomly with respect to those categories.

There will be no marital happiness issue if both partners do not watch porn, or both have seen it and want it banned, or if one partner has seen porn but that partner wants it banned. Naturally there would also be no issue if both partners watched porn and both want it legalized. That would be an example of the high adventure marriage mentioned above. The other combinations will result in unhappiness. If one partner watches porn and wants it legal, while the other wants porn to be illegal to all, then the outcome is bound to be unhappy. Finally, if only one partner watches porn but both want it legalized then there is potential for the non-watching partner to join the party. Based on those assumptions I did some number crunching using the GSS data for married people.

The marriages would distribute as follows
- 70.8% ‘no problem low octane’
- 14.3% ‘unhappy by reason of porn’
- 12.6% ‘unhappy by reason of porn with potential to convert to the ‘no problem high octane’ sort.
- 2.3% ‘no problem high octane’

Restricting things to those marriages where some sort of porn viewing is happening I get
- 16% no problem low octane
- 41% unhappy
- 36% potentially happy
- 7% happy high octane.

In theory 26.9% of marriages (14.3% unhappy plus 12.6% potentially happy) could face unhappiness due to the effect of porn. The generally accepted solution of asking the porn watcher to make a sacrifice, and move toward accepting a low octane marriage, is fairly negative. When there is no potential for the other partner to join the party this is a neutral-lose situation. For an economist this is akin to supporting declining industries, which is not in the best long term interests of stakeholders or the overall economy. Chances are there is a fundamental mismatch of outlook within the marriage and both would be better off ending it and searching for a better match. Potential partners who share the porn watcher’s outlook do exist in numbers sufficient to make a high octane life a real possibility. It’s not clear why preserving a low octane marriage is necessarily better.

When there is potential for the other partner to join the party the potential outcome is win-win but the standard solution is lose-lose. Attempting to convert the non-viewer is a better option. If that partner doesn’t prove to be open to joining the party then the situation changes to the former i.e. maybe it’s best to move on.

The anti-porn perspective on this is that porn negatively influences 27% of marriages and positively influences 2.3% marriages – a ratio of 11.7 bad to good - so exposure to it must be denied. The perspective argued above says that porn improves or has the potential to improve 14.9% of marriages and make 14.3% of marriages unhappy – a ratio of 0.96 bad to good and that even the bad isn’t necessarily bad, if moving on to find greener grass is accepted as an option.

The sociological and religious critique would say, correctly, that porn undermines the value of monogamy, marriage, children and a certain kind of staid vanilla sexuality. However they assume that these things are all indisputably good, or better than the alternatives. The Smart Vote (direction of difference between intelligent and stupid opinion) strongly contradicts that assumption. It says not getting married, cohabiting and having fewer children (both in and out of wedlock) are the smarter things to do.

It’s also smarter to accept (if not practice) alternative sexuality e.g. homosexual sex, swinging, BDSM, impersonal recreational sex, general sexual permissiveness, etc - especially if one controls for confounding factors.

As we shall see the Smart Vote is also pro porn being legally available.

The Smart Vote and Pornography

The General Social Survey has a number of questions on pornography. There are four questions on the effect of pornography – does pornography lead to rape, does it undermine morality, is it a useful source of sexual information, and is it an alternative sexual outlet? The GSS also asks whether pornography should be legal and whether the respondent had viewed an X-rated film during the previous year. I converted each of these to a common scale – a percentage between the most pro and most anti positions, with a higher number meaning more pro.

Before looking at these questions I looked at the Smart Vote on how important pornography should be, how well informed one claims to be, and how firmly one should hold one’s opinions. I found that the more intelligent don’t think issues about pornography totally unimportant but they don’t think it much more important than that. They are well informed on issues on pornography but do not claim to know all they need to, and say that while they are unlikely to change their minds on any of the issues there is a chance they will. The least intelligent option is to regard pornography as one of the most important issues or completely unimportant, and be very unlikely to change one’s views, while being extremely uninformed about pornography.

In the graph below I plot the mean scores on each of the main questions for each intelligence level.

Intelligent opinion is that exposure to pornography doesn’t cause harm, at least in the form of rape or undermining morality. This is pretty much in line with the results of the studies mentioned above. On the other hand intelligent opinion is also very slightly against the view that porn has benefits in the form of useful information or being an alternative outlet. In light of the above it should be no surprise that intelligent opinion is in favor of porn being legal. The Smart Vote though is for porn being illegal for those younger than 18 rather than for it to be legal for everyone. Actually watching pornography appears to have no relationship to intelligence.

It is possible however that there is no direct relationship and that these results could however be due to something else - like class, gender or age interests etc. To test this I ran multiple regressions on all these questions controlling for education, income, age and ideology separately for each gender – for whites only, to control for race too. Men are more positive about porn on every question than women.

Among men, only ideology matters with respect to any possible benefits of pornography. Only liberals think it provides useful information or serves as an outlet. Among women, younger and less intelligent women are more likely to agree with liberals.

The Smart Vote holds up strongly on pornography not causing harm – for both men and women – and younger, more educated, higher earning and more liberal people agree that pornography doesn’t cause rape.

The patterns are the same on the issue of pornography not undermining morality and the opinion that porn should be legal. The Smart Vote holds up very strongly again. Younger and more liberal people are more likely to accept both. More educated men are more likely to accept them too but income is not significantly related. Higher earning women are more likely to agree but education levels are not significantly related.

The Smart Vote says pornography is not harmful (and probably not beneficial either) but it cannot tell us which particular choice about pornography consumption is best. Older, and more conservative, men and women are less likely to consume pornography. More educated and lower earning women are also less likely to view X-rated films. In contrast higher earning women with less education are more likely to view X-rated movies.


The smart approach to pornography is to regard its consumption as a minor, largely harmless issue, and making it illegal for adults is stupid. The actual personal consumption of pornography is neither correct nor incorrect, in spite of its proven potential to change relationships.


1. Voluntary Exposure to Pornography and Men’s Attitudes Toward Feminism and Rape, Kimberley A Davies, The Journal of Sex Research, Vol 34 No 2, 1997, 131-137.
2. Pornography and rape: theory and practice? Evidence from crime data in four countries where pornography is easily available. Katchisky B. International Journal of Law Psychiatry, 1991: 14(1-2), 47-64.
3. The pleasure is momentary …. The expense damnable?: The influence of pornography on rape and sexual assault. Ferguson CJ, Hartley RD, Aggression and Violence Behavior 2009, 14(5): 323-329.
4. Pornography: Research Advances and Policy Considerations by Jennings Bryant, Dolf Zillmann.