"Like a bad teacher or parent, who keeps telling a child that they have little talent, are lazy, never get anything right and will never be successful, should not political spokespersons wonder why within the profession there are some who do not develop their talent, do less than they could and have poor self-esteem?" Mr McGinn asked.
Mr McGinn said low morale reflected the public's poor perception of the profession. It was little wonder recruitment was becoming difficult.
But despite their "unjustified treatment", teachers had delivered one change after another. They were at the heart of the success yet they needed more staff development, time to reflect and develop current practice and for curriculum development.
"It is perhaps no greater tribute to teachers that they continue to put pupils first while their own pay and conditions of service continue in relative decline," Mr McGinn said.