In my last post, I criticized Neil deGrasse Tyson, host of the new science series Cosmos, which is premiering tonight, for downplaying historical links between science and war. I pleaded with Tyson to speak out about the militarization of American science, which I fear is perpetuating war. Below is Tyson's response to my post, followed by my response to him.

Thanks, John, for your candid reflections on my public postures. I happen to be in contract on a book that explores the militarization of science. It’s half written, but it’s been slow to finish due to the making of Cosmos. I hope to submit it by year’s end. In any case, the book will not be a political manifesto — more of an exploration of the timeless relationship between of the needs of science and the needs of the military.

One important difference between the scientist’s peace movement of the Cold War and anything that has followed is that nuclear weapons, the foundation of Cold War terror, were the sole purview of physicists. So they carried an extra accountability for their existence and their ultimate proliferation.

Today, wars are fought with high-tech weapons such as drones, and smart bombs, space surveillance, and stealth technologies, all of which fall well-outside the moving frontier of theoretical particle physics. So perhaps the peace-loving scientists you seek should be drawn from the fields of information technology, nano-technology, or aerospace engineering. They can speak best and comment on the activities of their colleagues.

I repeat here, as you accurately quoted me above, but seemed to bypass: No scientist working for the government has a job outside of tax-based sources of support – paid by citizens in the service of national policy implemented by a Congress and a President. I can scream at lawmakers without limit, but their duty is to serve their constituents. And so it’s the electorate that I, as a scientist and educator, will always target for my messages.

Lastly, you speak as though all War is bad. I tend to agree with you on a personal level. But I know as a matter of political awareness that not all wars are unjust and some wars are, in fact, worth fighting. Many scientists who serve military interests do so because they believe deeply in the value of their work to the security of our country. To them, your letter above would ring hollow, especially since your best examples are drawn from four and five decades ago.

Respectfully submitted, Neil deGrasse Tyson, New York City

Neil, Thanks for your gracious, thoughtful response. I agree with you that in a democracy like ours, we all bear some responsibility for our nation's actions. So all of us—whether scientists, politicians or ordinary folks—should be concerned with all U.S. military activities, including research.

Yes, some wars have been more "just" than others. But over the last decade, the U.S. has waged two wars, with dubious justification, that have caused enormous suffering. And all wars—including WWII, the ultimate just war--have been horribly destructive.

No sane person wants war. So why can't we end war once and for all? You strike me as an optimist, who has faith in the fundamental intelligence and decency not only of scientists but of all people. I'm an optimist too. That's why I believe that humanity can solve the terrible problem of war. The only question is how.

Is the U.S. promoting peace by maintaining a gigantic military empire? By selling arms to the rest of the world? Are scientists promoting peace by engaging in weapons research? The aggressive U.S. deployment of drones has triggered an international arms race in the technology. Doesn't this trend imperil our security?

The more we ponder these issues, and debate them, the more progress we will make toward world peace, in spite of our inevitable disagreements about how to get there. That is my hope. That is why I write obsessively about war, and why I pestered you to speak out on the the militarization of science, which is a crucial piece of the puzzle of war.

So needless to say, I'm thrilled that you're writing a book on the topic! When you are on your book tour, I hope you'll give a talk at my school, Stevens Institute of Technology, which does a lot of defense research. Whatever your message is, we need to hear it.

Postscript: I talk with my pal George Johnson about Tyson's stance on science and war on a new segment on I also argue "Why the U.S. Military Needs to Shrink" on a recently posted "Big Think" video.