Which principle underlies the effectiveness of systematic desensitization?

You can't enjoy life if you are surrounded by things that induce anxiety is the principle behind the effectiveness of systematic desensitization.

"Systematic desensitization" is a kind of behavioral therapy which is mainly based on the principle of "classical conditioning".This therapy is mainly for those who faces phobia of being anxious.

This aims in removing the fear response of a phobia and will be substituted to relaxation response.In this therapy, the client imagines a situation and keep on picturing it in his/her mind until  it fails to evoke his/her anxiety that will be indicating the success of this therapy.The number of sessions required depends upon the severity of phobia. Other given principle are not the based on this therapy.

a factory opens that mass-produces light bulbs.

explanation:

not sure if that's an answer to your questions but this is an example! : )