In the end, it is ideas for which people kill each other.

Ideas have consequences, and totally erroneous ideas are likely to have destructive consequences.

One cannot prevent people from thinking what they please.

The only thing more dangerous than an idea is a belief. And by dangerous I don't mean thought-provoking. I mean: might get people killed.

Every thinker puts some portion of an apparently stable world in peril and no one can wholly predict what will emerge in its place.

In a war of ideas it is people who get killed.

Man is always ready to die for an idea, provided that idea is not quite clear to him.

It's the thinking that gets you killed.

Between any thinker and the truth, are all their opinions.

In a war of ideas it is people who get killed. 

Voltaire got it right long ago: ‘Those who can make you believe absurdities can make you commit atrocities.’ So did Bertrand Russell: ‘Many people would sooner die than think. In fact they do.

Fights over ideas are the most vicious of all. If it were merely food, or water, or shelter, we would work something out. But in the realm of ideas one can become idealistic.

The problem is that most people, most of the time, are desperate to believe ridiculous and divisive ideas for patently emotional reasons,and while rarely explicit what they're really worried about is death

For we all of us, grave or light, get our thoughts entangled in metaphors, and act fatally on the strength of them.