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Be a Skeptic: Ask Questions

Neil deGrasse Tyson

Lesson time 12:13 min

Asking questions is a tried-and-true component of scientific thinking. Neil talks about the processes behind informed skepticism as well as how to evaluate incoming scientific data.

Neil deGrasse Tyson
Teaches Scientific Thinking and Communication
Renowned astrophysicist Neil deGrasse Tyson teaches you how to find objective truths and shares his tools for communicating what you discover.


[MUSIC PLAYING] - So imagine someone comes up to you with some crystals, and they tell you that there's sort of a crystal energy embedded within them, and if you rub them together, this energy field will release, and it will enter your body and cure you of your ailments. All right, i have several things to say about that. One, it is equally as intellectually lazy for you to say, great, give them to me, how much, here's my money, I'll use them tonight, as it is to say, this can't possibly be true, get out of here, you're a charlatan. Both of those are equally intellectually lazy. If you're just taking what the person says, giving them money, that person could be exploiting your ignorance of the natural world and how it works. If you are rejecting what the person says, you didn't give yourself a chance to probe whether or not what the person said could be true. So what you need to do at this point is start asking questions. Where are these crystals from? What are they made of? What frequency of energy is generated when you rub them? On what ailments has this been tested? Can you show me those test results? Tell me about them so I can look them up. Let's look them up together. Was that research result verified by others? Is there a kind of disease that it does cure better than another disease that it maybe doesn't? You start asking questions. If only one experiment found that result or two or even only three, it's susceptible, because you could have been biased. You could have done an experiment that didn't really test what you were looking for, but masqueraded as though it was. There is all manner of things that could go wrong. I was observing the universe from a mountaintop in the Andes for my PhD thesis, and there was a 5 and 1/2 or 6 magnitude earthquake in the mountain. This is the Ring of Fire, the Andes Mountains that connects with the Rockies and up through the Aleutian Islands and down through Japan. It's a continental plate that's shifting, and on the edges of that plate, you have tectonic activity, which includes, by the way, the San Andreas fault is part of this. So I'm there in the Andes Mountains, and I'm getting spectra of stars. This is where you get light from a star, break it up into its component colors, and analyze it, and in there is a trove of information, what color the star is, what the chemical composition is, how is it moving, how is it rotating. And this has to be precisely calibrated, which it was until the earthquake. Unknown to me at the time, the earthquake shifted the platform on which the spectrograph was located. I started taking data again, once we recognized that the structure was safe, the telescope dome. And I noticed it looked really different. I was still getting spectra, but it was wacky spectra. I could have said to myself, wow, the star changed in the last few minutes, and I've just made a discovery. Or, I said, wait a minute, we just had an earthquake. I wonder if something got knoc...

About the Instructor

With a hit talk show and bestselling books, Neil deGrasse Tyson is one of the most popular figures in modern science. Now the influential astrophysicist teaches you how his mind works and how he connects with audiences. Learn to think like a skeptic, open your own mind through scientific literacy, distill data, and navigate bias to discover objective truths—and deliver your ideas in ways that engage, excite, and inspire.


Students give MasterClass an average rating of 4.7 out of 5 stars.

I loved this. No matter how many time I listen to this I always find what Tyson says so captivating and motivating.

Lots of good, interesting information … I appreciated his humor, too … but happily I learned a lot, too, and will explore some areas further. Thanks!

This class helped me with the ability to communicate with other in a more profound level.

As a venture Capitalist and business student Neil Tyson has made me even more curious today and the torch has been passed!



Thank you.. Ones makes one's point with evidence, but if it's not accepted, one can stop. One doesn't have to continue driving the nail in. We agree to disagree. Breathe.

A fellow student

Well, when Fox News stated that you can tell if you have Covid by holding your breath for 10 seconds... that was a bit much on faith. "We are done here". ???? Ok this tells me a lot of your personality. Listening to you will be like listening to Trump for now on. Perhaps some bit of knowledge will come from this but probably not much more than watching a series of Ramond.

A fellow student

In the previous lesson you spoke of how Uranus and Pluto were discovered. In that lecture you sated that when information was excluded from one observatory, due to calibration, that Pluto was then found to be in the correct place. This type of science is a P-type violation in scientific method. I understand that it worked, but it is still a violation.

Michele B.

I sell crystals for a living, we do get people that want the metaphysical meaning. I always figured if you can have a crystal radio or a memory chip that uses crystal, there is more to the crystals and people haven't tested them appropriately yet. On the other hand, when it comes to the healing stuff, I defiantly believe its a placebo effect. It's good for people to believe things but some common sense would be nice. I am not going to rain on their parade but I won't lie either.

A fellow student

At about 9:40+ you say I'm done with this guy. I find that interesting because he is being a skeptic as you say to do and in turn you dismissed him for what you are saying to do.

Bernardo F.

Sure it is hard to deal with this kind of people. Nowadays is even becoming more evident: people saying that the SARS-CoV2 was made in a laboratory, sharing posts claiming that an alkaline diet can cure it, doubting on vaccines, ignoring climate change... I understand that we live in a free planet and everyone can believe what they want; however, ignorance is creating problems. I mean, if it was just a decision whose consequences arrived to the one who made that decision, that would be ok. But even authorities are making those decisions, affecting a huge ammount of people. Is that acceptable?

Hana N.

After the lesson, I found my self struggling with the visualisation for the question "At what point do research results achieve the status of an objective truth?". I do really like the story about the person who came to you and stated that he didn't believe that human landed on the moon. Do you have any example like that for the process of achieve the status of the objective truth?

M S.

I find the episode about the Moon being illogical. Neil asks a man not to believe to the authority, yet, gives an official website, which represents an even higher level of authority!

Ryan D.

I enjoyed Neil's approach to dealing with someone who refuses to believe the evidence given to him. Neil gave him evidence to back up the claim that the man disputed, but the man wasn't willing to believe it. The problem was not with Neil's argument or evidence, but with the man himself. It shows that he was not a "proper" skeptic, according to Neil's definition. Instead of asking questions about something he was unsure of and then recognizing the valid evidence presented, he rejected the truth and opted for his own version. He was not willing to change his mind or allow for information that ran contradictory to what he believed. Neil realized this and stopped engaging with him, for he knew that the man would not believe what he was shown - this prevented Neil's time from being wasted.

Bart B.

Not true completely to me : truth is intrinsic . That means it never need to rely on a social platform. When truth requires an agreement from others to become accepted as truth , It is not intrinsic or unbiased . But I know , truth is what makes other believing the same . Unfortunately that is not truth but more intrinsic value.