In “Nuclear War Should Require a Second Opinion” [Science Agenda], the editors argue that the president of the U.S. should not be the only person to decide on whether or not to cause worldwide havoc by ordering a nuclear launch and that “we need to ensure at least some deliberation.”

Alone or through informed advice and widespread consent, threatened by enemies or not, an American president (or any other president) should never have the power to destroy the world. The U.S. has countless other ways to make adversaries sorely regret threatening it.

STELIOS BAKALIS Thessaloniki, Greece

Your editorial's recommendation introduces ambiguity. Would it be desirable for the president to consult “high-ranking members of Congress” after a first strike, or the imminence of one, when these members might themselves be divided? And how many need to affirm? To minimize delay and the possibility of error, might not it be better to require the secretary of defense or the national security advisor, or both, to certify that there is unmistakable evidence that these weapons have been used?

What constitutes evidence would be clarified by a policy of “no first use” (NFU) of nuclear weapons. NFU draws a bright line between when the use of such weapons is justified—in particular, to retaliate against their first use by another country—and when it is not. If one side adopts it, it is in the interest of the other side to do so to prevent a nuclear Armageddon, at least given that both sides have second-strike capability (as the U.S. and Russia do).

For a state like North Korea, which does not have such capability, retaliation by the U.S. would almost certainly wipe out its future capability and annihilate its leadership. So even though North Korea may not agree to NFU, it would be foolhardy for it to seriously consider a first strike, which translates into its implicit adoption.

STEVEN J. BRAMS Professor of politics, New York University


In “Building a Better Harvest,” Marla Broadfoot reports on efforts to utilize the phytobiome—the web connecting crops with environmental factors such as microbial communities—to avoid famines. I appreciate that crop science aims to adopt a more holistic approach. But I am somewhat perplexed by Broadfoot's assertion that yields must increase by 70 percent, as concluded in a 2009 United Nations Food and Agriculture Organization (FAO) discussion paper, to satisfy population growth and increasing meat consumption.

Before trying to increase crop yields, we must find ways to reduce inefficiencies in our food production and distribution. About a third of edible food is wasted globally, and the FAO found that 6.7 percent of global greenhouse gases comes from food waste. Further, a June 2010 report by the United Nations Environment Program urged a global shift toward a plant-based diet to fight hunger, poverty and climate change. And adoption of such a diet would make people healthier. China has already recognized the environmental and health threat posed by growing meat consumption and has developed a campaign to reduce it by 50 percent by 2030.

OLGA SYRAYA Düsseldorf, Germany

Broadfoot's article largely ignores an important consequence of crop yield increases: they can depress market prices for the crops. Unless they provide more income despite falling prices, higher yields may do the farmers more harm than good.

In addition, although Broadfoot concludes with a brief mention of the problems involved in getting food into the hands of the starving, that observation conceals an important point: if we stopped putting our crops into the bellies of cattle and ethanol fermenters and the hands of dictators, we could probably feed the world right now without having to increase yields, and doing so would also reduce pressure on the environment created by high-intensity agriculture. Sometimes human problems require human solutions.

GEOFF HART via e-mail


“Talking to Ourselves,” by Charles Fernyhough, discusses studies on the neural bases of people talking to themselves in their mind. I wonder if any research has been done to determine if such “inner speech” is still present in people suffering from dementia or Alzheimer's disease—or if it is present but in a different form. My mother-in-law sat motionless for hours, unable to speak to us, and I always wondered if she still could speak to herself.

SANDRA ROBBINS Carlsbad, Calif.

I would like to know if any of the brain pathways found in the research on self-talk could be similar to dreaming. It seems like dreaming might be an uncontrolled visual re-creation of the process.


FERNYHOUGH REPLIES: Regarding Robbins's question: Inner speech is difficult to study. In the case of individuals with dementia, the problem of obtaining reliable reports on inner experience is even more acute. It appears likely to me that inner speech will continue in people who, for reasons including dementia, don't use much spoken language. One possibility for investigating such speech in dementia would be to develop nonverbal measures, such as pictorial representations of aspects of inner speech, that could be used with individuals who express little external language.

In answer to Schroeder: Dreaming occurs mainly (though not exclusively) during the rapid eye movement (REM) sleep stage, when activity in the brain's cerebral cortex is similar to that observed when people are awake. Methodologically, tying particular dreams involving speech to activation in language and other pathways would be extremely hard. One way forward might be through obtaining detailed self-reports on dreams by adapting existing techniques of experience sampling. But making such methods work with a sleeping participant—perhaps awoken by a prompt or beep and invited to report on the dream—would be challenging indeed.


“A Matter of Choice,” by Peg Tyre, investigates the results of school vouchers and finds that they have led to lower scores in math and reading. I was dismayed that the article did not answer the question posed under its title: “So why has the Trump administration embraced them?”

The article discusses everything but the proverbial gorilla in the room, which is that public education is but another segment of the public trust that is being directly and systematically dismantled in the name of private profits.

MOHAMMAD BABAR Jefferson City, Mo.


In “Technology as Magic” [TechnoFiles], David Pogue invokes the name “Jeeves” in reference to instructing a hypothetical butler. Pogue must get these things right: the original Jeeves, created by British author P. G. Wodehouse, was not a butler. “If the call [came], he [could] buttle with the best of them,” but he was, in fact, a “gentleman's personal gentleman”—a valet.



In “The Roots of Science Denial” [October 2017], an editors’ note incorrectly states that a draft of the Climate Science Special Report was leaked to the press. The draft had been made available for public comment months earlier. We regret the error.