IMAT 2015 Q3 [Conclusion | Intelligent Life]

Now, it might be thought an amazing coincidence if Earth were the only planet in the galaxy on which intelligent life evolved. If it happened here, the one planet we have studied closely, surely one would expect it to have happened on a lot of other planets in the galaxy – planets we have not yet had the chance to examine. This objection, however, rests on a fallacy: it overlooks what is known as an ‘observation selection effect’, so it wouldn’t be such a coincidence. Whether intelligent life is common or rare, every observer is guaranteed to originate from a place where intelligent life did, in fact, arise. Since only the successes give rise to observers who can wonder about their existence, it would be a mistake to regard our planet as a randomly selected sample from all planets.

Which one of the following best expresses the main conclusion of the above argument?

A. Our planet is not a randomly selected sample from all planets.

B. However common intelligent life is, every observer will certainly originate from a place where intelligent life did, in fact, arise.

C. If life had evolved here on Earth, it would probably have happened on a lot of other planets in the galaxy.

D. There would be no amazing coincidence if we discovered that Earth were the only planet in the galaxy on which intelligent life evolved.

E. It would be an amazing coincidence if Earth were the only planet in the galaxy on which intelligent life evolved.

Key Steps

  1. Read the question (do this for every question!)
  2. Read the passage
  3. In your own words, make a conclusion for the passage. What is the author’s main idea?
  4. Find a sentence in the text that matches the conclusion you made, and underline it.
    -Keep an eye out for giveaway words and phrases
  5. Find an answer that matches the underlined sentence.

A Our planet is not a randomly selected sample from all planets.

This is an irrelevant option choice. We are looking for other planets besides Earth that may have evolved life. The fact that it is randomly selected or not, does not change the argument. You are only trying to prove the fact that there is more life (planets) with intelligent life, you are not running trial experiments. Therefore A is incorrect.

B However common intelligent life is, every observer will certainly originate from a place where intelligent life did, in fact, arise.

This is a supporting point to the conclusion. It shows us that it is actually not such a crazy idea to believe that there are no other planets with life and that ours is unique because it shows that observers are guaranteed to have originated from places of intelligent life. Since we are observers, we come from intelligent life, but it means that we cannot assume there are more out there because we cannot observe them at the moment. Therefore B is incorrect.

C If life had evolved here on Earth, it would probably have happened on a lot of other planets in the galaxy.

This is another example of the Observation selection effect. We say in our head that because we exist, there must be other beings on other planets, but there is no basis for this besides the mere fact we tell ourselves. The author is trying to prove that the idea of there no being other intelligent life should be less surprising. Therefore C is incorrect as it is opposite to what the author is trying to show us.

D There would be no amazing coincidence if we discovered that Earth were the only planet in the galaxy on which intelligent life evolved.

This is what the author is trying to prove. The author introduces the argument by providing the opposition view (‘it might be thought that’) and then goes into the evidence to show us why it is actually not that surprising if we discover that there is no highly intelligent life on other planets. The main support is the ‘observation selection effect’, which states that observers are guaranteed to originate from a place where intelligent life arises. This says that because we are observers, we are going to believe that it is possible for this to occur in other places even if we are not sure. So since we are observers, we cannot assume that there is intelligent life on other planets and therefore it would not be an amazing coincidence if Earth was the only planet in the galaxy on which intelligent life evolved. Therefore D is correct.

E It would be an amazing coincidence if Earth were the only planet in the galaxy on which intelligent life evolved.

This answer choice can be discarded by reading the first sentence in the text. It uses the sentence ‘it might be thought an amazing coincidence if Earth were the only planet in the galaxy on which intelligent life evolved, but the use of this wording clearly shows a refute to come later in the passage. The author then refutes this by saying that it would not be an amazing coincidence because there is something called the observer’s effect, stating that only planets with intelligent life can observe. This would make it not a great coincidence that Earth is the only planet where intelligent life can evolve because only planets with this life can give arise to technology, and without it, there are no observables. Therefore E is incorrect.