Psychometric validity is one of the central concepts in psychological assessment. It is a characteristic the presence of which signifies that an assessment and the inferences drawn from the results of the assessment were executed properly and warrant endorsement. However, psychometric validity is also a concept surrounded by controversy. This controversy is largely philosophical and brings to bear classic debates in the philosophy of science over scientific realism and empiricism. Much of the current debate over psychometric validity is simply a debate over what constitutes measurement in the psychological sciences and what are reasonable aspirations for those who construct and administer psychological tests.