"Just the facts, ma'am." That was Joe Friday's interrogation refrain on Dragnet. The same comment could serve as the subtitle of Thomas Sowell's recent book, Discrimination and Disparities. Few works on politically explosive topics maintain such a consistent focus on empirical evidence while avoiding rhetorical jabs at opponents. On the other hand, empirical evidence cuts deep, especially when critics can't protest the author's "nasty" style. As radio talker Larry Elder observes, "[f]acts are to liberals what kryptonite is to Superman."

Sowell's title, if employed by a member of the leftist intelligentsia, would doubtless imply a causal link between statistical disparities and some form of discrimination – usually racial. Sowell, by contrast, marshals an abundance of evidence to show that this automatic assumption isn't justified. Focusing simply on statistical probabilities, Sowell notes that if five prerequisites are needed for success in a particular field, and if the chances are two out of three that any person will have each characteristic, the chance of possessing all five characteristics are still only one in eight – a calculation that helps explain why most pro golfers have never won a PGA tournament while Arnold Palmer, Jack Nicklaus, and Tiger Woods have collectively won over 200 times. Consequently, "[g]iven multiple prerequisites for many human endeavors, we should not be surprised if economic or social advances are not evenly or randomly distributed among individuals, groups, institutions or nations at any given time."

Among leftists, assumptions about the random distribution of characteristics stand at the heart of various discrimination suits. Thus, if proportionately more blacks than whites are given tickets for speeding, this statistic provides for them prima facie evidence of racial discrimination. Sowell, however, offers clear counter-evidence that black drivers are more likely to exceed the speed limit than white drivers. Similarly, the assumption that racial discrimination is the primary reason blacks are overrepresented in the prison system is countered by noting that blacks are vastly overrepresented as both perpetrators and victims of murder – a crime that's hard to ignore. Sowell further observes that fatherlessness clearly increases the likelihood that a person will end up in prison since a majority of prisoners "were raised with either one parent or no parent" – a domestic circumstance that applies to well over half of all black kids in the U.S.

In short, Sowell shows that many or most of the disparities that afflict black Americans are due to behaviors to which even other blacks have objected. In the early twentieth century, for example, longtime black residents in Chicago publicly chastened new arrivals from the South for behaviors that would, and eventually did, have negative repercussions for the entire community. Today, however, most black leaders ignore the plain fact that merchants in high-crime areas, for example, must charge higher prices to squeeze out lower profits than stores in safer parts of town – preferring to blame the proprietors' racist-fueled greed. Only blacks who have moved to safer suburbs can be counted on to protest government policies that again place large groups of unsavory characters near them under the failed assumption that a middle-class environment will alter bad habits.

Sowell also provides surprising examples of cases where the desire for profit actually won out over racial discrimination. Early in the twentieth century, for instance, attempts to maintain a white Harlem were foiled by the sheer economic advantages available to landlords who ignored the neighborhood's segregation policy. Likewise, privately owned municipal transit groups and railroads both protested and often ignored laws that mandated segregated facilities. Indeed, railroad management actively worked with Homer Plessy to overturn segregation mandates in that industry – a legal effort that ended unsuccessfully with the Supreme Court's Plessy v Ferguson "separate but equal" decision in 1896. Amazingly, Sowell shows how the profit motive often trumped segregation laws and compacts even in Apartheid South Africa and in the post-bellum South. Put succinctly, it was racist politicians, not transit owners, who insisted that Rosa Parks sit at the back of the bus.

Sowell focuses additional attention on well intended government policies that succeeded in increasing, not decreasing, racial disparities. In this regard, significant space is devoted to the negative consequences of minimum wage legislation. Sowell notes that in 1948, when the minimum wage was economically inconsequential, black teen unemployment was actually lower than white teen unemployment and a fraction of its rate when the minimum wage was substantially increased. Sowell also laments the destruction of a traditionally stellar black educational institution, Dunbar High School in Washington, D.C., when self-sorting, education-focused black families and students were subjected to politically driven and empirically destructive fantasies that involved bussing and the abolition of selective institutions like Dunbar.

Similarly, in order to racially "unsort" neighborhoods (as they "unsorted" schools), politicians ignored economic facts that explain why banks (including black-owned banks) disproportionately rejected blacks' mortgage applications. Instead, legislators insisted that financial institutions lower lending standards to achieve the politically desired "random" racial distribution of house ownership – a misbegotten policy whose economic chickens came home to roost in 2009. Meanwhile, various government laws that decreased the supply of housing and increased prices were "successful" at reducing the Bay Area's black population in 2005 to less than half its number in 1970.

Throughout the book, Sowell discusses a number of other factors that clearly lead to "disparities," leaving aside the kneejerk assumption of racist motives. Being first-born or an only child, for example, has immense advantages – benefits indicated by the fact that twenty-two of the twenty-nine original Apollo astronauts fell into one of those two categories. Additionally, in a chapter titled "The World of Numbers," the author debunks several beliefs about disparities rooted in false assumptions about statistics and the lack of economic mobility. Thus, one study found that 95% of the people in the bottom income quintile were no longer there fifteen years later and that 29% of them had risen to the top quintile. Elsewhere, Sowell explains how falling "household" incomes are consistent with rising "personal" incomes simply because the average size of a household has fallen substantially. (A two-person household where each individual earns $20,000 represents a household income of $40,000. But if both members of the household begin to earn $30,000 and establish separate residences, the income of each one-person household is now 25% below what it was before.)

Much of Sowell's book is recapitulated in his final chapter – and with a bit more rhetorical intensity than previously exhibited. A few new topics, like the destructive consequences of a grievance mentality and "black English," are also addressed.

Overall, Sowell's book is a protest against the unfounded assumption that "there would be no disparate outcomes unless there were disparate treatment." Sowell observes that this ideologically driven assumption "seems almost impervious to evidence." Accordingly, those who cling to this dogma with religious fervor will likely avoid Sowell's fact-filled book like kryptonite. Folks with less dogmatic proclivities, however, would do well to peruse this concise work.

Richard Kirk is a freelance writer living in Southern California whose book Moral Illiteracy: "Who's to Say?" is available on Kindle.