This article was originally posted on RealClearScience.

There exists the distinct possibility that monkeys live on Mars. In the year 2015, it is not possible for scientists to completely rule out the scenario. So, imagine a hypothetical conversation between the monkey-on-Mars believer (we’ll call him “Monkeyman”) and an astrobiologist.

***

MONKEYMAN: I believe there are monkeys on Mars.

ASTROBIOLOGIST: There probably aren’t.

MONKEYMAN: NASA has not thoroughly investigated this issue. Haven’t you seenPlanet of the Apes? I think there is a technologically advanced monkey civilization living on Mars. I’m afraid they may be planning to come to Earth someday. Can you prove me wrong?

ASTROBIOLOGIST: We have a lot of photographs of Mars. We haven’t seen any monkeys.

MONKEYMAN: Of course you haven’t seen any monkeys. They live deep underground. It’s a technologically advanced society.

ASTROBIOLOGIST: There is very little reason to believe that life exists on Mars, let alone monkeys. We have sent eight landers to Mars, and we have not detected any signs of life — plant, animal, or microbial. Besides, there is no liquid water on Mars, and our understanding of biology is such that it seems liquid water is essential to life. Though I wish it wasn’t the case, Mars probably never had life on it.

MONKEYMAN: You’re assuming too much. We only know about life on Earth. It is possible life elsewhere has evolved not to need water. Besides, these monkeys are so technologically advanced, that they probably could harvest comets for any water they might need.

ASTROBIOLOGIST: A technologically advanced civilization would emit some form of detectable electromagnetic radiation, such as radio and TV waves. If such a civilization existed on Mars, we would have detected the signals by now.

MONKEYMAN: Are you not listening to me? These monkeys are very advanced. They know we’re listening to them. So, they have devised a system of communication that is undetectable. Perhaps they use telepathy.

ASTROBIOLOGIST: I think we’re losing touch with reality. Every time I provide evidence that you are wrong, you dismiss it and find an excuse to hide the monkeys somewhere else where scientists haven’t looked. You are making claims that are essentially unanswerable. That’s not how science works. Extraordinary claims require extraordinary evidence. So the burden of proof is on you, not NASA.

MONKEYMAN: Look, I’m just asking questions. If there aren’t any monkeys on Mars, then all NASA needs to do is show me the evidence. Where’s the evidence?

ASTROBIOLOGIST: I just gave it to you.

MONKEYMAN: That proves nothing. Why aren’t you being honest? What are you hiding? Who’s paying you? You’re just a shill. You’re a disgusting traitor to humanity.

ASTROBIOLOGIST: *Blank stare*

***

Does this conversation sound familiar? It should. While no sane person believes there are monkeys on Mars, plenty believe in other scientific conspiracy theories, namely ones involving vaccines, GMOs, and climate change. Though the topics are different, the same flawed logic and gross misunderstanding of science underlie the conspiracists’ claims.

The debates often start off reasonably enough. Good questions are asked, and competent answers are provided. However, the answers are ignored, and increasingly unreasonable questions are asked. That’s when the conversation quickly goes downhill. Conspiracy theorists refuse to read reputable peer-reviewed scientific literature, instead relying on dodgy websites for information. Worse, the inability of the scientist to provide 100% proof — because providing such proof is impossible in science — results in the conspiracy theorist insisting that all beliefs are equally likely. Eventually, frustration sets in on both sides, and the conspirator often makesad hominem attacks and accusations of fraud.

Sadly, this is why so many scientists refuse to engage with the public. Many conspiracy theorists have no real interest in learning the truth.