What is “evidence” in psychotherapies?

editorial. 2019 Sep 9;18(3):245–246. doi: 10.1002/wps.20654Scott O Lilienfeld1,2,✉PMCID: PMC6732681PMID: 31496105The concept of evidence‐based medicine (EBM), whichoriginated in the early 1990s at McMaster University (Canada) and spread to the UK and North America, heralded an effort to place medicine on firmer scientific footing. EBM's overarching goals were twofold: to establish hortatory (“thou shall”) standards, guiding practitioners toward scientifically‐supported interventions, and minatory (“thou shall not”) standards, guiding them away from scientifically‐unsupported interventions.Soon, EBM found its way into the field of psychotherapies. Evidence‐based psychotherapies are commonly conceptualized as a three‐legged stool. One leg comprises the best available evidence bearing on the efficacy (beneficial effects in rigorously controlled conditions) and effectiveness (beneficial effects in real‐world conditions); the other two comprise clinical expertise and patient preferences/val...