Elliot Lewis

Logical fallacy and appeals to the emotional in decision making is something I have re-learned in a new way and I like it!

Wason Selection Task, Four Card Problem

If you have four cards, each with a number on one side and a letter on the other. You are presented with A, B, 1 and 7. You are told that “if there is an A on one side, there is a 7 on the other”, you must decide which cards to turn over to prove the statement true.

Now you choose A, because that’s obvious. What next? You might want to choose 7, because you want to know if 7 has an A. But who cares? The question was “if there is an A..” and there may be a C with a 7, and that is no contra to the rule. Just as, you wouldn’t care to look under the B, because that’s also irrelevant. You would however want to know if there was a 1 under an A, so you ought to check the 1.

Humans aren’t designed with inbuilt propositional logic calculators. We are social beings who think in faces and emotions. If the question were poses as each card has an age and a drink, presented with 12, 35, beer and water, you would immediately dismiss both the 35 and water cards as something that cannot disprove the statement.

So chosing A (or 12) is natural as we’re interested in the Modus Ponens, we want to affirm the rule. You would then be wrong to choose the water or 7, because this is trying to affirm the consequent, which can only prove that “people over the legal drinking age can only drink beer” or “only a 7 can have an A”.

How to Deny the Consequent and Influence Zeroth Order Logic

So, maybe I’m too autistic to have understood this before, but it turns out that people don’t believe you when you just tell them numbers and expect them to believe you. Trust, as I’m told is a function of credibility plus reliability plus intimacy. To get over the hurdle of convincing people that something is true, to influence them to see your solution to a problem, they have to intuitively feel it as well as know it. By rationalising it as childred can’t drink beer, only then can you feel instinctively that it doesn’t matter what the 7 has. If only it were as simple to do the same for the Monty Hall problem.

When we are testing our hypothesis and working through problems, it’s very instinctive to keep following the “what is right” route when interrogating and testing ideas. By continuing to chase positive responses, we end up inadvertently asking for to affirm the consequent. That is, if I pose the problem “find the rule behind the sequence: 2, 4, 6” you may persist with “8, 10, 12” and “5, 6, 7” which are all correct. But you don’t necassarily think to the contra and test for “6, 4, 2” which would be a confirmation of the negative to prove that the sequence is “numbers which increase”. Unless you’re already primed to break the logic, your inclination is to look for a confirmation that the 7 card has an A behind it.