A method for detecting software defects includes selecting from a target program comprising a plurality of modules a first module for evaluation and isolating the first module. The method also includes iteratively performing the following steps until the first module has been reduced such that a validation program is able to determine whether the first module contains a defect: generating an environment surrounding the first module, the generated environment preserving at least one external constraint on the first module; reducing the size of the first module; and reducing the number of program states associated with the first module.