This is such an exaggerated claim. * Plenty of studies inherently cannot survive 20 years. Send out a survey and ask people "on a scale of 1 to 10 how happy a

This is such an exaggerated claim. * Plenty of studies inherently cannot survive 20 years. Send out a survey and ask people "on a scale of 1 to 10 how happy are you". These results will not match the results in 21 years simply because the population you are studying is different. This example is simplified, but explains why many results change over time. * Plenty of studies have survived 20 years, and those that study psychology are really clear about which knowledge is foundational and which is on more questionable ground. The Big Five personalty traits is about 40 years old and has been found to be consistent across cultures. A ton of psychological research around psychological responses has survived the test of time. * Psychologist often relay on more questionable data than other scientists because it's much cheaper and easier for psychologist to collect questionable data than other sciences. This allows for a wider exploration and makes research much more accessible. Anyone reading a paper with this type of data will be naturally skeptical. I am specifically referring to data collected from self-reported questionnaires, often collecting a sample that generalizes poorly over interesting populations.