Recent high-profile intelligence failures - from 9/11 to the 2003 Iraq war - prove that cognitive bias in intelligence analysis can have catastrophic consequences. This book critiques the reliance of Western intelligence agencies on the use of a method for intelligence analysis developed by the CIA in the 1990s, the Analysis of Competing Hypotheses (ACH). The author puts ACH to the test in an experimental setting against two key cognitive biases with unique empirical research facilitated by UK's Professional Heads of Intelligence Analysis unit at the Cabinet Office, and finds that the theoretical basis of the ACH method is significantly flawed. Combining the insight of a practitioner with over 11 years of experience in intelligence with both philosophical theory and experimental research, the author proposes an alternative approach to mitigating cognitive bias that focuses on creating the optimum environment for analysis, challenging current leading theories.