[akiselev]

For something to be predictive in a scientific sense, it has to be repeatable. There is so much variety in individuals and their environments that most social sciences have little repeatability - they mostly study affluent western college students who have time to volunteer for college psychology studies. However, if you're mostly an affluent western college student, chances are that you can take some value out of the studies because they're selected for your environment rather than humanity as a whole (which is what they purport to do by claiming to study 'psychology' rather than western college students specifically).

Closest analogy off the top of my head is psychiatric drugs: their efficacy is generally bottom of the barrel except for some group with factor X (each drug has their own unique factor X). For the vast majority of these drugs, we have no method of screening for whether a person has factor X - we don't even know what it is most of the time - so doctors have to go through a process of trial and error with patients until they find the right drug or combination. Once they do, it's like a night and day difference for the patient, yet if we applied the same standard of evidence for psychiatric drugs that we do for blood pressure pills, we'd never make any progress. A lot of the drugs look like they don't work in phase III and we have no way to predict which drug which help which patient but the patients figure it out with their doctors because they have actionable data, even if it isn't predictive in general.