Robert K. Merton made important refinements to functionalist thought. He fundamentally agreed with Parsons' theory but acknowledged that Parsons' theory could be questioned, believing that it was over generalized. Merton tended to emphasize middle range theory rather than a grand theory, meaning that he was able to deal specifically with some of the limitations in Parsons' thinking. Merton believed that any social structure probably has many functions, some more obvious than others. He identified three main limitations: functional unity, universal functionalism and indispensability. He also developed the concept of deviance and made the distinction between manifest and latent functions. Manifest functions referred to the recognized and intended consequences of any social pattern. Latent functions referred to unrecognized and unintended consequences of any social pattern.