A weakness of the psychodynamic approach is that many of the concepts cannot be empirically tested. For example, concepts such as the id and the Oedipus complex are said to occur at an unconscious level, so they cannot be proven or disproven to exist. According to Popper, this is a weakness because the psychodynamic approach does not meet the scientific criterion of falsification. Therefore, the psychodynamic approach cannot be considered scientific and is therefore regarded as a pseudoscience