A simple idea underpins science: trust, but verify". Results should always be subject to challenge from experiment. [But] modern scientists are doing too much trusting and not enough verifying-to the detriment of the whole of science, and of humanity. Too many of the findings that fill the academic ether are the result of shoddy experiments or poor analysis. A rule of thumb among biotechnology venture-capitalists is that half of published research cannot be replicated. A leading computer scientist frets that three-quarters of papers in his subfield are bunk. In [2010] roughly 80,000 patients took part in clinical trials based on research that was later retracted because of mistakes or improprieties. One reason is the competitiveness of science. As their ranks have swelled, to 6m-7m active researchers on the latest reckoning, scientists have lost their taste for self-policing and quality control. The obligation to "publish or perish" has come to rule over academic life. Competition for jobs is cut-throat. Every year six freshly minted PhDs vie for every academic post. Nowadays verification (the replication of other people's results) does little to advance a researcher's career. And without verification, dubious findings live on to mislead. Careerism also encourages exaggeration and the cherry-picking of results. Failures to prove a hypothesis are rarely even offered for publication, let alone accepted. "Negative results" now account for only 14% of published papers, down from 30% in 1990. Yet knowing what is false is as important to science as knowing what is true.