Who challenges the way you think? In the past year, say, whose remarks punched you in the gut, momentarily caught you speechless, left your mind to linger in distraction while the conversation, and life, moved on? It's a different question that who taught you something new, and the answer, I suspect, is less obvious. Your list might include some familiar teachers – university professors, op-ed columnists, perhaps a religious figure – but it probably continues with many who are not paid to teach. My father, grandmother, and uncle belong on my list, as do a few close friends, a novelist, two singers, a playwright, a photographer, and a twelve-year-old boy from Bhaktapur, Nepal, who offered to guide two ignorant hikers down a shady shortcut. I suspect your list is an equally diverse collection of strangers, and that we share few names, if any. Still, I'm willing to bet that some of your names would have found their way on to my list, and that my friend from Nepal would have joined yours, had introductions been made.

The fundamental purpose of Topic is to make those introductions. Each issue selects a universal topic that guides our readers through a uniquely diverse collection of thinkers. Beyond responding to the topic at hand, the only other requirement of a contribution is that it makes our list, it must challenge the way we think. We publish writers, photographers and illustrators of all professions, ages, and nationalities. The result is both coherence and diversity: a variety of voice on a common topic.

Topic is a product of today's world. The same global forces that threaten to produce mindless conformity also promise the opposite. The growth of the Internet, the ease of travel, and the spread of the English language may blur distinctions between cultures, but they also facilitate conversation – they shrink the world, but also expose it. There has always been a world of opinion and experience relating to every topic imaginable. Never in history has this information been nearly as accessible as it is today.

Nor has it been more relevant. If the first years are any indication, the twenty-first century will be a dangerous one for hermits, intellectual or otherwise. We ignore others' knowledge and opinions at our peril. We compromise the richness of our own thoughts when we stop allowing others to challenge the way we think. Topic introduces new voices so as to revitalize the public debate.

This first issue of Topic examines war through original writing from 1917 to 2002. You will read reflections, impressions, opinions, suggestions, warnings and love letters. You will read of may wars, some less familiar than others. There are few opinions that our contributors share. Still, out of these twenty-four pieces emerges a common conviction that war demands critical thinking.

In a 1918 to her overseas lover, Evelyn Salzman describes New York as "the same old New York, in spite of all its mass of people whose lives must be so very different from what they used to be." She recounts the opening of the new 7th Avenue Subway and describes a city that "forgets the world in its excitement at its own growth." War, she realizes, is surprisingly easy to ignore.

Topic, we hope, will make it harder to forget the world. There will always be new 7th Avenue Subways to distract us, projects to consume us. But I hope, as Evelyn Salzman did, that as we go on in our routines, we leave time to remember and reflect, explore and discover, challenge old thoughts and form new ones.

One starts an enterprise like this because one thinks that the world needs it. Our world is vast, often joyful and transparent, sometimes sinister, and frequently deceitful: but the world is also knowable. One of the great works of life is to share knowledge with others, and this, essentially, is the work of a magazine. Topic will offer you our best: the most incisive thinkers, a large and swiftly moving net of issues, and the enthusiasm of curious souls.

Let us offer you every Topic as a doorway onto a new world, where insight is always fresh, and intellectuals are still hopeful. We choose the theme of War for our first issue because people are fast becoming aware that thinking about the past and future of war is of utmost importance in the post 9/11 world. William McBride's essay on the military preparedness take on serious questions about where we see war is and what we may miss. We offer you such articles because our writers glimpse greater problems that are too often overlooked.

Serious choices are at hand whenever there is violence in the world. It does us no good if the media and the intellectuals stagger each other with repetition. America, the sleeping giant, is up and thinking about preparation. The media has clamored about censorship and community, about exclusion and newfound patriotism. Their ears are tuned mostly to each other: the BBC reads the Spectator, and NPR watches CNN. Yet serious decisions call for serious and different ideas: our best hope in the Middle East, or Korea, or Ireland, as in our daily lives, is to hear the voices of people who understand the question with new sharpness. What we promise you is their voices: the most articulate and relevant available.

Hopefully, our writers will ask questions you haven't thought about before. We hope they will show you something unique: because the twenty-first century world demands a broader awareness to make sense of the endless variety. We hope to address the serious, but we also hope to brighten eyes with vivid curiosity. The best way to effect social change may be to change day-to-day life. Our writers will take you to the opera in Kyrgyzstan, to war-torn Zimbabwe, through the reckless games of World War II soldiers on the Pacific front. We choose the best in storytelling because the personal experiences of these places are compelling. We share the variety with you because the experiences of another place or generation helps when one is eager to see past the constrictive categories of the mind.

An earlier generation believed that educated people would be at home anywhere in the world. We want to bring that world to you. Topic is for the reader who hates to lose any part of that world to time. Topic is for anyone who wants to engage the world and try to understand it. We invite you to enter each Topic, for if you let this diverse world start to surround you, it may also transform you in the process.