The thesis of cognitive behavior therapy (CBT) is something like

Depression is caused by distorted thought patterns, called cognitive distortions.

Some categories of distorted thought patterns are:

  • All or nothing thinking “I got a question wrong on the test so I’m a failure”
  • Discounting the positive / mental filter
  • Should statements
  • Jumping to conclusions / mind reading
  • Labeling Seeing failings as character deficits rather than bad actions
  • Over-generalization
  • Emotional reasoning (assuming that your emotions are accurate) (e.g., “I feel bad, so I must be bad.“)