Does a Possibly Make a Probably?

We all make mistakes in our thinking – fallacies. Confusing something that is possible with something that is probable is the possibility fallacy. The following report is a fictional example of this fallacy.

Special Report: Moon Landing Hoax

In 1969, NASA announced they landed a man on the Moon. However, there is growing evidence that this was a hoax.

It started when veteran photograph analyzer “Allan” began to question whether it was possible to land on the moon. “I found we couldn’t have done it,” he says. “The technology just wasn't there in 1969. Computers were merely glorified calculators.”

“But what about the pictures of astronauts on the moon?” you say. Allan and his team studied the Apollo photographs and concluded, “There are literally tons of problems. Our discoveries suggest these pictures were actually taken in a Hollywood studio.”

No Stars
Photo A

For example, look at Photo A. Where are the stars? “On the moon there isn't any atmosphere, so you should see more stars than on Earth.” But you can't see a single star!

"C" on Rock
Photo B

Now look at Photo B. Do you see the “C” someone drew on the rock? This probably meant the rock went in a certain place on the stage – they just forgot to turn it upside down.

Another question Allan asks is, “How is it possible they took so many pictures? The average temperature on the moon during the day ranges from 260° F to 280° F. How did the film in the cameras survive? At that temperature photographic film would melt.”

Why did NASA fake the moon landings? Allan says the answer is simple. “We were in the Cold War with Russia, and we wanted to show the world that we were better.”

Did This Report Convince You?

This report shows that it is possible the NASA moon landing was a hoax. (1) Maybe we can’t see the stars because it was all faked. (2) Maybe there’s a “C” on the rock because it was a studio prop. (3) Maybe the film would melt if it were taken to the moon. So, it is possible that NASA astronauts didn’t land on the moon.

But remember, a possibly doesn’t make a probably. There is lots of evidence that NASA didland on the moon. Imagine a balance scale: on one side, we put evidence that NASA did land on the moon and on the other side we put evidence that NASA didn’t.

The evidence that NASA did land on the moon includes:

  • All the photos and videos are evidence. There may be some unexplained things in the photos, but the existence of the photos does support the moon landings.
  • Today scientists can study moon rocks the astronauts brought back. These rocks are different from anything found on Earth.
  • Thousands of scientists worked on the Apollo program. None of them say it was a fake.
  • NASA has explained all the anomalies found in the photos ([url=http://www.thursdaysclassroom.com/index_01apr01.html]http://www.thursdaysclassroom.com/index_01apr01.html[/url]).

Difference between Possible and Probable

All of us can confuse these important ideas: (1) what is impossible, (2) what is possible, and (3) what is probable. Let’s explain the difference.

1. Something is impossible if there is no way that it could be true.

Jack realized he’d made a revolutionary discovery. When you add two plus three underwater, you always come up with seven. Every math textbook must be rewritten!

2. Something is possible if there is a chance that it could be true.

Little Girl : Mom, is it possible the hospital switched me at birth and I’m really a princess?

Mother : Yes, but it’s not likely. Now eat your asparagus – even a princess must eat her asparagus.

3. Something is probable if it is more likely true than not true. We must weigh the evidence and decide.

Annoyed Dairy Farmer: Dulcy got out of her pen again, and I can’t find her – she’s probably on the other side of the moon.

Calm Wife: No, she always goes for my strawberries – that’s where you’ll probably find her.

If someone chooses to believe a possibility while ignoring evidence that supports an obvious probability, he is using the possibility fallacy .

Our cure for this fallacy is to look at the evidence as if we were holding a balance scale. We look at the evidence, and we filter out the possibilities that are probably not true. This is hard for people like us! We never want to throw away our favorite possibilities. But we need to get this right; so many choices in life can depend on judgments like this.

Exercises

In the examples below, indicate whether what is said is (1) totally impossible, (2) possibly true, or (3) probably true. No evidence is given; simply use your knowledge of history, science, or the Bible.

  1. Moses and King David were great friends. They often went out for a milk shake at Checker’s drive-in.
  2. Abraham Lincoln decided to grow a beard after a little girl wrote him a letter saying he’d look better with one.
  3. The tallest mountain in the lower forty-eight states is west of the Mississippi.
  4. Iowa Farm Boy: “Mom! Dad was out plowing the cornfield, and the tractor almost fell in a new volcano that’s forming out there! Call the fire department!”
  5. NASA’s Opportunity rover has found evidence of water on Mars.
  6. Homeschooling Today magazine is actually a covert CIA operation used to send coded messages to agents in Argentina.
  7. Honeybees never sting when they’re foraging for nectar.
  8. Grandpa, with four-year-old grandson on his knee: “When I was your age, I did mountain climbing. I remember the day I summited on Everest alone. . . .”
  9. Read the following example and choose whether A or B is the wiser choice based on the evidence in the story.

Advertisement: “Invest in our lead teacups – this is how the super-rich protect their wealth! We know the price of lead teacups hasn’t changed for two hundred years, but this is only a trick. We’ve studied the market, and we have secret information that the price of lead teacups will soon go through the roof!”

  • A. I should invest because it is possible lead teacups will increase in value.
  • B. I should not invest because lead teacups will probably not increase in value.


"Moon Landing Hoax" from Logic in 100 Minutes DVD

Answers

  1. Impossible. The Bible says Moses was dead before King David was born.
  2. Probably true.
  3. Probably true.
  4. Possible. It’s always possible a new mountain will form in Iowa.
  5. Probably true. NASA is a reputable institution.
  6. Possible.
  7. Nathaniel: “Probably true.” Hans: “Impossible. I’ve been stung in the eye by one of Nathan’s bees when I wasn’t near the hives.”
  8. Impossible. It is not reasonable that a four-year-old could climb Mount Everest alone.
  9. B. If the price of lead teacups hasn’t changed for the past two hundred years, it’s not likely it will today.

First appeared in Homeschooling Today magazine, September-October 2004.

Facebook Comments

Site Comments

1 • Ted Kalal • May 26, 2008 • 3:49 PM

Some observations:

1. Check out this moon launch of the Luinar Lander. See how it takes off without any exhaust and notice how the camera that is taking the launch video pans up just at the right time to capture more of the take off. Who or what was panning the camera up? (http://www.fotosearch.com/DVA003/023-0035/) See the rocket engine in this NASDA photo.  There is an engine that cannot be seen in the launch film.

2. The Lunar Lander had four legs.  Four legged things wobble on non flat surfaces.  Didn’t they think of this way back in 1969?

3. The Mars machine has three legs.  Apparently the leg designer improved the reliability of the Mars machine by eliminating one leg AND he must have had some cow milking experience because milking stools have three legs. I believe the Mars machine is there alright.  It’s not going to come back, I believe that’s the plan, because launching it still doesn’t work. Hmmmm . . .  39 years later and they discover three legged stools.

ted

2 • Mike Heinemeier • July 01, 2008 • 10:09 AM

1. The Lunar lander blasted off in non atmosphere and the exhaust gases would not be visible. You can see the blast from the dust movement.

2. The blast from the exhaust moved the camera up slightly during takeoff. If there were someone operating the camera they didn’t do a very good job of panning up as it was only an inch of movement and didn’t follow the lander for more than a second or two.

3 • jim • September 24, 2009 • 2:24 AM

the space station is 250 miles from earth, them moon is 250,000 miles away from earth, have you ever been to the smithonian , and see the capsule they returned on, about the size of a cadillac. Give me a break…From the space station they dont even get close up pics of the moon. They didnt even send a rat or monkey up there, so dont be mad PETA

4 • david quiles • July 06, 2010 • 10:18 AM

it’s impossible to take a picture under the sun and have the stars visible. The stars need a long exposition (minutes) to make something in the film, the sunlight just need a very small fraction o time to make it. If you make the exposition for the stars, the lunar surface and the astronauts should have been overxpossed, totally white with a big glow. If the astronauts resisted the temperatures, so the film did.

5 • Drew • August 26, 2010 • 12:09 PM

Hi Nathaniel!
I feel like there’s a missing element or type in your progression, one which shows up in a couple of your examples and exercises.
I think the term “plausible” is a relevant middle ground between identifying that which is merely possible (but perhaps highly unlikely) and probable (a word which evokes a very high degree of likelihood).
In the case of the nissing cow, while i agree that the mother’s testimony to the cows penchant for getting into her strawberries would still make that answer the most probable, i would think that these two possibilities would be far from the only possible answers. For instance, knowing a cow’s love for clover, she could be on another side of the barn where she might have found a section of grass with a particularly nice patch of the tasty stuff. THAT possibility and others like it could be among a group of PLAUSIBLE explanations—-that is, explanations that represent a significantly greater degree of plausibility than the farmer’s unlikely (fanciful, hopefully facetious, pretty much IM-possible) suggestion.
Further, in Exercise/Example #2 Lincoln’s decision to grow a beard could have many explanations, not limited to a handful of very PLAUSIBLE explanations—-for instance, Abe just got tired of the whole irritating process of shaving; Abe thought he might look more distinguishes and evoke a greater degree of wisdom and authority with a beard; Mary Todd could have expressed a hitherto secret “thing” for men with beards…etc.  These, among others, must all be admittted to being PLAUSIBLE explanations—-and i guess i would consider them no less plausible than the little girl story.  In fact, with the historical penchant for legends to grow around the bios of national and world leaders, the little girl story might justifiably to some people sound a bit….mythical… or at least certainly not worthy of the designation “probable” (or highly likely) when compared to one or two of the other plausible scenarios.
In many examples like this one, it’s sometimes true that none of the various plausible scenarios stands out as being the most likely…and we are often left to admit that we’re not sure which one is more probable.
I think an improved (more precise and maybe more useful) progression might be evaluating explanations for events by identifying the differences between moving from the impossible, to the possible, to the plausible, to the probable.

All of that said, i still wouldn’t consider the idea that there wasn’t any moon landing to be either evidentially compelling or even remotely plausible!

Just FYI, while i’m not a christian, i found your Tree of Logic posting very helpful! (and i’m not someone who would be a priori against home schooling—with appropriate guidelines)

Thanks for the thought-provoking site!
Drew

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