LAWRENCE KRAUSS: One of my favorite quotes, which I've used in my writing, comes from the former publisher of The New York Times who said, "I'd like to keep an open mind, but not so open that my brains fall out." And that's the key point. We have to skeptically assess the information we receive, we can't be gullible because when we get a lot of information it's absolutely certain that some of that information is wrong and so we have to always filter what we get and we have to ask ourselves the following question: how open does my brain have to be to accept that information? Does it have to fall out? And by that I mean, when someone tells you something you have to ask: is this consistent with my experience? Is it consistent with the experience of other people around me? And if it isn't then probably there's a good reason to be skeptical about it—it's probably wrong. If it makes predictions that also appear to be in disagreement with things that you observe around you, you should question it. And so we should never take anything on faith. That's really the mantra of science, if you want, that faith is the enemy of science. We often talk about a loss of faith in the world today; you don't lose anything by losing faith. What you gain is reality.
And so skepticism plays a key role in science simply because we also are hardwired to want to believe, we're hardwired to want to find reasons for things.  In the savanna in Africa, the trees could be rustling and you could choose to say, 'Well there's no reason for that,' or, 'Maybe it's due to a lion.' And those individuals who thought there might be no reason never lived long enough to survive to procreate, and so it's not too surprising we want to find explanations for everything and we create them if we need to, to satisfy ourselves, because we need to make sense of the world around us. And what we have to understand is, what makes sense to the universe is not the same as what makes sense to us and we can't impose our beliefs on the universe. And the way we get around that inherent bias is by constantly questioning both ourselves and all the information we receive from others. That's what we do in science and it works beautifully in the real world as well.
When you're presented with questions or answers about any problem there are a few questions you can ask yourself, that you should ask yourself right away. First of all, you can ask yourself, 'Do I like this answer?' And if you do you should be suspicious because you're much more likely to accept something that appeals to you whether it's right or not. So if you inherently like something in some sense that's a reason to be almost more suspicious of it, if you're a scientist. But then you can ask the question, when you're presented with information, is that information consistent with what I know already based on data I've taken about the world around me? And by data, it's not just scientists. If you're a child—all children do this—you put your hand in a flame, okay, the second time you know not to because you have the data that it hurt the first time. And if someone that tells you, 'That flame isn't going to hurt,' you have the data to assess that that's probably wrong. So you want to ask yourself: is that information consistent with what I know to be true already?
And the other thing to do, especially if you get information from a source you don't know, is to look at many different sources and compare them and see if they all agree. If they all agree it doesn't guarantee it's right but if there's vast disagreement between the different sources then it's highly likely that you can't at least rely on that information to be true. It's the same way science works: science doesn't prove what's absolutely true, what it does is prove what's absolutely false. What doesn't satisfy the test or experiment we throw out. What remains may not be true but we shrink it down, as Sherlock Holmes would say, and what remains after all of that is done is likely to be true. So many sources, question what you see and whether it's consistent with what you already know, and be suspicious of your own likes and dislikes when you accept information. That's probably the reason we shouldn't, when we turn it to the Internet, go to echo chambers and just read the sources that we like.
Now having said that, if you look at many sources you could also quickly decide which ones are not reliable and throw them out. If they're not reliable in one case then you should be highly suspicious of them in the future. So we all turn to different sources that we think are more or less reliable based on our past experience. Try that and I think it's one great way to filter out a lot of the nonsense on the Internet.When I talk about being skeptical it is important to recognize that you could be surprised and something that you don't think is sensible can end up being a sensible. That's the way we learn things in physics. So when someone presents you with an idea that may seem strange it's reasonable to be skeptical of it, but it's worth pursuing long enough to see if it might make sense and to listen to arguments that might be convincing that might cause you to change your mind. In fact there's a great school of pedagogy that says: the only way we actually learn anything is by confronting our own misconceptions. So once again, while it's reasonable to be skeptical of external information, if you're always skeptical of your response to information and what your misconceptions are and what your prejudices are, then you will both guide yourself not to accept nonsense but also you will be willing to realize that sometimes what you think is skepticism is really myopia.