Teaching statements are justified as a mechanism to evaluate classroom ability but are poorly suited for that purpose. Indeed, it is hard to imagine how someone could ever get one wrong. How horrible would a teaching philosophy have to be for it to be a principal factor in precluding an applicant from securing a job or being promoted?
The most intractable problem with teaching philosophies is that they are literary exercises, and it is an open question as to whether someone who writes an inspiring one is actually a good teacher. Authors of impressive statements have demonstrated that they are good at the keyboard, not necessarily in the classroom.
via chronicle.com