This is a book intended to advertise narratives of free immigration as grievance-payments. It is a polemical and ideological manifesto, not scholarly research on immigration.
To deliver his message, Mehta uses a mix of emotional (at times sanctimonious) storytelling, obtuse and partisan reporting of self-serving data & events, deliberate omissions of facts, frequent scapegoating and (at times) aggressively contentious rhetoric.
Some points:
1) Immigration to a developed country is touted by Mehta as a form of payment for perceived (though at times exaggerated) wrongs of recent times and, when those are not available, for historic wrongs (dating back as far as needed).
In his masterpiece "Sapiens", the famed writer and Oxford historian Yuval Harari, had noted that following the beginning of the Scientific Revolution (16-17th Century), an unprecedented explosion in scientific and technological innovation has enabled a few nations to have a disproportionately large impact on the world (so vast that, as Harari noted, one could cherry pick "enough" of "evidece" to try and promote almost any point of view, from the fringes of exclusively highlighting only the good or the bad, to presenting more accurate interpretations). Mehta fits the former category and mostly cherrypicks the wrongs, trying to present not solid arguments but pretexts in support of policies he supports. Sure, there are plenty of (for example) Churchill's actions & policies which deserve criticism or worse (e.g.: his role in the Bengal famine of 1943) for the millions of lives destroyed. Yet, there were also people and developments like Norman Borlaug's (father of the Green Revolution, whose work is credited with saving over a billion lives from starvation especially in the developed world). One does not excuse or replace the other, and talking about historical "debts" while exclusively focusing on one and completely ignoring the other, is dishonest, at the very least.
In Mehta's view, the countries he's moralizing (some of which are deemed guilty by association for sharing the same continent with the UK, France & co) must accept any accusations brought their way (and open their borders) while the people who want to emigrate for economic or personal reasons don't share much responsibility for the state of their home countries or communities (be it Syria or Somalia, in Mehta's view, all the bad things happening there are the fault of rich countries ). Personal agency is ignored or denied by Mehta in several places throughout the book. For example the "best and brightest who have been educated at the greatest expense of the struggling states they come from" (according to Mehta) have been simply "took" by developed countries (it does't matter that the people in question, although "best and brightest" are free individuals who have made their choices and have selected those choices likely to deliver more personal and professional opportunities).
One theme put forward by the book, is that some immigrants are like "creditors": some colonial power came to their home country, took "wealth and diamonds", but now they, the "creditors", have come to collect. Mehta uses the example of one of his grandfathers (who immigrated to the UK) to illustrate the argument. The grandfather, however, did not seem to notice the symmetry of his argument: that creditors can have their own creditors (e.g.: in his case, the vast masses of lower-caste Indians, like the Dalit, who can claim millennia of oppressed status that have benefit upper-caste members like Mehta's grandfathers). But while the grandfather, and later Mehta himself, demand special treatment for the debt they think is owed to them, they never talk about the same type of debt they owe others (if one was to continue their line of reasoning).
2) Throughout the book, the US (and to some extent Europe) are blamed for conflicts, wars, pollution, and many more problems. Sometimes the criticism seems fair, often is exaggerated. For example: in Syria, the US has its fair share of blame for the war. So have other players (including Assad's dictatorial regime, its Iranian allies, Russia, ISIS and the other terror groups, etc) and is dishonest to put the entire cost of the war on US.
3) When discussing immigration numbers to the US, Mehta focuses a lot on smaller venues for legal immigration (e.g.: the Green card lottery - which currently offers about 50,000 green cards/year) and much less on the bulk, which is dominated by:
(a) illegal immigration, which currently averages more than 100,000 people/month at the Southern border alone, and has seen staggering numbers of 700,000 -> 1,600,000 people/year for 30 years since the 1970s;
(b) spouses, children, parents, and more distant relatives of legal immigrants/citizens who usually exceed 700,000/year;
etc
He (correctly) points that Irish immigrants have considerably benefited from the Morrison visa program (they got about 40% of the 120000 visas) but ignores programs that have benefited Latin American groups (e.g.:NACARA 202 and NACARA 203 which have granted permanent residency to 68000 Nicaraguans, 122000 Salvadorans and 55000 Guatemalans)
Equating the deportation of undocumented immigrants to "ethnic cleansing" (page 139) is also sensationalist and dishonest.
4) If a country decides to take in millions of migrants at some times, it does not mean it has the obligation to do the same every-time, for every given year. Mehta believes there are no arguments demonstrating long-term socio-economic damage to countries that accept immigrants, even in large numbers. This is currently a subject of debate among economists, with conflicting arguments that are being too often driven by ideology, not data. Currently among developed nations those having low immigration levels (South Korea, Japan, etc):
- do just as fine, if not better, economically when compared to countries with much large levels of immigration;
- rank at the top in terms of innovation (South Korea ranks 1st in the World; Japan 5-6th);
- have much lower crime levels across the board
- have much more social cohesion, and are less socially segregated.
5) The impact of immigration on crime is shallowly addressed in the book. Some studies show immigration reduces crime in some cases while other show that it leads to increased crimes in other cases. Crime levels also vary a lot among immigrant groups (some contribute far less crime than the native population, while other contribute much more). The studies are often dependent on the data-samples chosen, the geographic areas and the time-windows they examine, e.g.:
- in the US, some studies (e.g.: Reid, Weiss, Adelman (2005)) show that immigration to large US metropolitan areas does not increase, and in some cases decreases, crime rates
- other studies(e.g.: Barranco, Shihadeh & Evans (2017)) suggest that immigration does not play a significant part in lowering crime rates
- in Germany, things look different: studies and official statistics from 2017, 2018 & 2019 that look at the past 3-5 years have found that foreigners (overall 12.8% of the population) are over-represented in crime stats (e.g.: 34.7% of all crime suspects; 29.7% for murder and manslaughter; 41% burglaries; etc). Also in Germany, some studies show that while 1st generation immigrants did not have elevated crime rates (1950-1980), second- and third-generation immigrants had significantly higher crime rates.
- in Canada, most studies show that immigration has been more likely to reduce crime (the country's immigration point-based system that favors people of certain skills and educational background is given partial credit)
- in Norway, reports by the Norwegian statistics bureau found that immigrants are over-represented in crime statistics but that there is substantial variation by country of origin. Similar patterns have been documented in Switzerland, Spain and other countries.
6) When discussing global warming and the pollution of the environment as "arguments" to why developed countries should accept more immigration, Mehta uses similar double standards, blaming games and partisan editorializing. His arguments (e.g.: blaming the US and Europe for all the problems) fall short when one actually looks at data. For example: currently, 22 of the Top-30 most polluted cities in the world are in India. Not too long ago, the top spot was held by China, who has made significant progress towards improving things (e.g.: the average concentration of pollutants fell in Chinese cities by 12%, between 2017 and 2018 alone). While China saw improvement, however, many neighboring countries saw major increases in pollution, including Indonesia, South Korea, Vietnam and Thailand. Local institutions and policies can play, thus, significant roles in addressing or accelerating pollution problems throughout the World and the significant increase in worldwide pollution (e.g.: about 60% increase since 1990) has little to do with most Western countries which, with a few notable exceptions (US, Canada,Australia) have decreased their own emissions by considerable margins.
Regarding pollution, there're several ways to look at the problem quantitatively, a more popular one being looking at CO2 emissions (and even in that case multiple views that provide partial, incomplete perspectives are usually discussed in the research literature, e.g.: per capita emissions, emission intensity, increase over time, cumulative emission per year, etc). Mehta ignores most peer-reviewed literature which points to the massive shifts among major polluting countries that have dominated the past 30 years, as more and more countries industrialize across the world:
- UK, for example, was the 2nd largest polluter in Europe, in 1990. By 2017 its emissions have dropped steadily, reaching 64% of its 1990 levels. Since 1970, Iran, South Korea, Mexico, and Saudi Arabia have steadily increased their emissions, by 2010-2012 reaching comparable levels or even exceeding those of the UK in the 90s (and continue to grow, since)
- the global CO2 emissions in early 1900s were less than 2 billion tons/year (5% of what they are today); by the 1950s they reached close to 6 billion tons/year which is 15% of what they are today, less than the level of the 2004 emissions in China alone, and about half of what China was producing in 2017.