LSAT Prep: Correlation vs. Causation

LSAT Blog LSAT Prep Correlation vs. Causation
The world is full of people taking correlational relationships to be causal ones.

Here are two examples I've come across recently for you to dissect:

1. An advertisement in the New York City subway consists of the following:

So, the evidence is the correlation (in yellow):

"Kids of teen moms are twice as likely not to graduate than kids whose moms were over age 22."

And the conclusion is the text in the top-right:

"I'm twice as likely not to graduate high school because you had me as a teen."

(Note the "because" in the conclusion, which suggests that there's a causal relationship between these two characteristics.)

What potential confounding factors is the advertisement failing to consider as alternate causes?

2.  An article in The Atlantic titled "The Case for Getting Married Young" states:

Unmarried twenty-somethings are more likely to be depressed, drink excessively, and report lower levels of satisfaction than their married counterparts. For example 35 percent of unmarried men say they are "highly satisfied" with their lives compared to 52 percent of married men; among the women that report being "highly satisfied" with their lives, 29 percent are cohabitating, 33 percent are single, and 47 percent are married.

This paragraph is promoted as evidence for the implicit conclusion that getting married young can lead to greater happiness.

Does this necessarily mean that getting married young causes twenty-somethings to feel highly satisfied with their lives? What is the author failing to consider in using this survey as part of his evidence?


Please leave your thoughts on both of these examples in the comments!


  1. Both of examples neglect to consider the possibility that: the proposed cause and effect are both effects of a third common cause. For example, lack of intellectual curiosity might lead one to have baby young and not pay much attention to the intellectual development of the child. Irrational fear of any sort of commitment might lead people to remain single and assume less responsibility, which is arguably a precondition to accomplish anything that amount to satisfaction.

  2. I think the first one is well-put. No major fallacy.

    1. Even the second one. Note the word "can"

  3. In the yellow highlighted area, It can be understood that the women, if she has a child, will only be graduated if her age is over 22.

  4. Obviously, Example #1 targets subway riders who've never taken the LSAT, while Example #2 is strikingly similar to those given in "A Rulebook for Arguments", Steve's recommended text for all LSAT test-takers. Anyone who can't instantly spot the flawed reasoning in both examples should read Chapter V, Rules 18-21 in that book. Understanding the arguments' weaknesses is perhaps the most essential skill you can develop toward mastering the LR sections on the LSAT. (If only the LR questions could be this easy!)

  5. #1 There could be be other factors, such as a reading disability, why a child may not graduate other than having been born to a a young teen.
    #2 Twenty somthing married couples can be depressed too.

    1. I was twenty-something when I got married and suddenly my wife ran off with some guitar player.

      Boy was I depressed.

  6. #1 - is failing to take into account the subjective socioeconomic factors, whether the child grows up in a single-parent family, whether there are substance issues involved, many immigrants have children younger than north americans and they generally dont have access to all the resources that many citizens do

    #2 - the married portions of the study may be at a better place financially, which is why they were able to get married in the first place, living in a two-income household they have better methods of support

  7. I don't think that the teens reading the poster in the subway are too concerned with logic fallacies.
    But good point for the LSAT studying people.

    1. I don't think the teens can even read!

  8. The odds of children graduating high school is directly proportional to the age of the teacher.

    Also suppose the teen mom graduates high school while she is pregnant? Doesn't that mean that the baby participated in the graduation?

    Why am I asking these questions?

  9. First of all, that baby is one ugly baby!

    They don't need a babysitter because nobody is going to kidnap that baby.

  10. They do not have flawed reasoning. They both are statistical and avoid using extreme words that may imply some kind of causal relationships.