Personality and Individual Differences
“Explain This Person” Courtroom
One fictional behaviour, eight explanations that all fit it, and a jury that has to work out which of them could ever have been wrong.
Fictional case — there is no correct answer
Learning objective
By the end you should be able to tell an explanation that fits from one that predicts, and say what evidence would choose between two accounts that both fit.
About 25 minutes. Nothing you do here is saved or sent anywhere.
How this is scored
Not on picking the right explanation — there isn't one. The verdict responds to whether you requested evidence that discriminates, whether your confidence is proportionate to what that evidence can support, and whether you kept compatible explanations alive instead of forcing a single cause. Converging confidently on one answer is scored down.
The case
Priya is fictional. Her behaviour was written to be compatible with every explanation offered below — which is not a trick, but the ordinary condition of explaining somebody from the outside.
The jury room
Key terms
- Fit and prediction
- Whether an account can accommodate what has already happened, and whether it commits itself to something not yet observed.
- Underdetermination
- More than one account remaining compatible with all the evidence available.
- Compatible and competing
- Two accounts that could both be true, as against two that cannot. Only the second pair can be chosen between.
Rate, investigate, decide
Rate every explanation on how plausible you find it, then request the evidence you would want. Watch what the evidence does — and what it cannot do.
Before you can return a verdict
Where each explanation stands
| Explanation | Your rating | After evidence | Distinctiveness |
|---|
Request evidence
What came back
The verdict on your verdict
| Pair | Relationship |
|---|
What this demonstrates
Fitting is cheap; predicting is not
All eight explanations accommodate the behaviour, because all eight were written to. That is not a flaw in the case — it is what most behaviour is like. What separates them is not how comfortably they fit what you have already seen but how much they commit you to about what you have not: an explanation that predicts the same as every rival cannot be tested against any of them, however true it happens to be.
Underdetermination is the normal situation
The evidence available does not select one explanation, and no amount of thinking harder about it will. This is not a failure of reasoning; it is a property of the evidence. The useful response is to say precisely what would settle it — which is why the six-month follow-up is on the list and marked unavailable.
Compatible is not the same as competing
A great deal of argument about why people do things is conducted as though every explanation excluded every other. Most do not. A person can have a strong achievement motive, high self-efficacy in this domain, values that made the silence uncomfortable, and be responding to a real incentive — all at once, and all truly. The diagram joins only the pairs that genuinely pull in opposite directions, and there are fewer than students expect.
Confidence should track the evidence, not the story
A coherent narrative feels like knowledge. The test is whether your confidence would have been lower had the evidence come out differently — and for explanations that predict nothing distinctive, the answer is no, because no result could have disturbed them.
For teaching elsewhere: take this activity as one self-contained block of HTML, on the clipboard or as a file. Either way it is styled so that it will not disturb the page you put it into.