A researcher's theory predicts every score will land between 40 and 60. Six results come back: 44, 38, 52, 47, 55, 49. The researcher argues that five of six confirm the theory, so it is strongly supported. Why does Popper's criterion make the single 38 more informative than all five hits combined?

A. Because the theory forbade any score outside 40-60, and 38 happened.

A theory predicting 40–60 says nothing about the five results that fell there, one predicting 30–70, or nothing at all, would have accommodated them equally well. Those five could not discriminate a good theory from a loose one; the 38 could. Watch for the rescue: widen to 35–60 and the theory has stopped forbidding anything.