He highlights the role of nation-state monopolies on force, of commerce (making other people become more valuable alive than dead), of increased literacy and communication (promoting empathy), as well as a rise in a rational problem-solving orientation as possible causes of this decline in violence.

The decline in violence, he argues, is enormous in magnitude, visible on both long and short time scales and found in many domains including military conflict, homicide, genocide, torture, criminal justice, and treatment of children, homosexuals, animals and racial and ethnic minorities.

Pinker rejects what he calls the "Hydraulic Theory of Violence" – the idea "that humans harbor an inner drive toward aggression (a death instinct or thirst for blood), which builds up inside us and must periodically be discharged.

[5]Pinker also references ideas from occasionally overlooked contemporary academics, for example the works of political scientist John Mueller and sociologist Norbert Elias, among others.

They co-wrote a New York Times op-ed article titled "War Really Is Going Out of Style" that summarizes many of their shared views,[7] and appeared together at Harvard's Institute of Politics to answer questions from academics and students concerning their similar thesis.

[9] In Bookmarks, the book received 3.5 out of 5 stars, with the critical summary saying, "Pinker levies his data with humor to make it more palatable to lay readers, and his lucid, fluent prose renders difficult concepts understandable".

The idea that we live in an exceptionally violent time is an illusion created by the media's relentless coverage of violence, coupled with our brain's evolved propensity to notice and remember recent and emotionally salient events.

Pinker's thesis is that violence of all kinds – from murder, rape, and genocide to the spanking of children to the mistreatment of blacks, women, gays, and animals – has been in decline for centuries as a result of the civilizing process...

"[19] In a long review in The Wilson Quarterly, psychologist Vaughan Bell calls it "an excellent exploration of how and why violence, aggression, and war have declined markedly, to the point where we live in humanity's most peaceful age.... [P]owerful, mind changing, and important.

"[21] Political scientist James Q. Wilson, in The Wall Street Journal, called the book "a masterly effort to explain what Mr. Pinker regards as one of the biggest changes in human history: We kill one another less frequently than before.

But to give this project its greatest possible effect, he has one more book to write: a briefer account that ties together an argument now presented in 800 pages and that avoids the few topics about which Mr. Pinker has not done careful research."

[23] Clive Cookson, reviewing it in the Financial Times, called it "a marvelous synthesis of science, history and storytelling, demonstrating how fortunate the vast majority of us are today to experience serious violence only through the mass media.

"[24] The science journalist John Horgan called it "a monumental achievement" that "should make it much harder for pessimists to cling to their gloomy vision of the future" in a largely positive review in Slate.

[25] In The Huffington Post, Neil Boyd, Professor and Associate Director of the School of Criminology at Simon Fraser University, strongly defended the book against its critics, saying: While there are a few mixed reviews (James Q. Wilson in the Wall Street Journal comes to mind), virtually everyone else either raves about the book or expresses something close to ad hominem contempt and loathing... At the heart of the disagreement are competing conceptions of research and scholarship, perhaps epistemology itself.

In doing so, he takes a critical barometer of violence to be the rate of homicide deaths per 100,000 citizens... Pinker's is a remarkable book, extolling science as a mechanism for understanding issues that are all too often shrouded in unstated moralities, and highly questionable empirical assumptions.

"[29] In a reply, Pinker denied that his arguments had any similarity to "great moderation" arguments about financial markets, and stated that "Taleb's article implies that Better Angels consists of 700 pages of fancy statistical extrapolations which lead to the conclusion that violent catastrophes have become impossible... [but] the statistics in the book are modest and almost completely descriptive" and "the book explicitly, adamantly, and repeatedly denies that major violent shocks cannot happen in the future.

"[30] Taleb, with statistician and probabilist Pasquale Cirillo, went on to publish an article in the journal Physica A: Statistical Mechanics and its Applications that proposes a new methodology for drawing inferences about power-law relationships.

In a 2018 article in the journal Science Advances, computer scientist Aaron Clauset explored data on the onset and lethality of wars from 1815 to the present and found that the apparent trends described by Pinker, including the "long peace", were plausibly the result of chance variation.

Braumoeller found no evidence of consistent upward or downward trends in any of these phenomena, with the exception of interstate uses of force, which steadily increased prior to the end of the Cold War and declined thereafter.

R. Brian Ferguson, professor of Anthropology at Rutgers University–Newark, has challenged Pinker's archaeological evidence for the frequency of war in prehistoric societies, which he contends "consists of cherry-picked cases with high casualties, clearly unrepresentative of history in general.

"[40] To Ferguson, [b]y considering the total archaeological record of prehistoric populations of Europe and the Near East up to the Bronze Age, evidence clearly demonstrates that war began sporadically out of warless condition, and can be seen in varying trajectories in different areas, to develop over time as societies become larger, more sedentary, more complex, more bounded, more hierarchical, and in one critically important region, impacted by an expanding state.

Despite recommending the book as worth reading, the economist Tyler Cowen was skeptical of Pinker's analysis of the centralization of the use of violence in the hands of the modern nation state.

Epstein also accuses Pinker of an over-reliance on historical data, and argues that he has fallen prey to confirmation bias, leading him to focus on evidence that supports his thesis while ignoring research that does not.

John N. Gray, in a critical review of the book in Prospect, writes, "Pinker's attempt to ground the hope of peace in science is profoundly instructive, for it testifies to our enduring need for faith.

Pinker argues in his FAQ page that economic inequality, like other forms of "metaphorical" violence, "may be deplorable, but to lump it together with rape and genocide is to confuse moralization with understanding.

He asserts that Pinker's book "promotes a fictitious, colonialist image of a backward 'Brutal Savage', which pushes the debate on tribal peoples' rights back over a century and [which] is still used to justify their destruction.

Douglas P. Fry of the University of Alabama at Birmingham stated that "recent assertions by Steven Pinker and others that violent death in the Paleolithic was shockingly high are greatly exaggerated.

In March 2018, the academic journal Historical Reflections published the first issue of their 44th volume entirely devoted to responding to Pinker's book in light of its significant influence on the wider culture, such as its appraisal by Bill Gates.

The issue contains essays by twelve historians on Pinker's thesis, and the editors of the issue Mark S. Micale, Professor of History at the University of Illinois, and Philip Dwyer, Professor of History at Newcastle University write in the introductory paper that Not all of the scholars included in this journal agree on everything, but the overall verdict is that Pinker's thesis, for all the stimulus it may have given to discussions around violence, is seriously, if not fatally, flawed.

The problems that come up time and again are: the failure to genuinely engage with historical methodologies; the unquestioning use of dubious sources; the tendency to exaggerate the violence of the past in order to contrast it with the supposed peacefulness of the modern era; the creation of a number of straw men, which Pinker then goes on to debunk; and its extraordinarily Western-centric, not to say Whiggish, view of the world.