Former coach Mickey Arthur, who was sacked before the first of the back-to-back Ashes series in England, cast doubt on the longevity of some of the players, including 32-year-old captain Michael Clarke, who is managing a back condition.
"I read Mickey Arthur's comments about the need to rebuild, and I don't really want to get into it because I don't want to start another furore. But I think he's wrong," Harris said in a column published by Melbourne's The Age newspaper on Friday.
"If you're older and you're good enough to play at this level, then you should be picked.
"If you nick off all your old blokes, who are the younger ones going to learn from?"
Australia's selectors have traditionally been the whipping boys of a feisty local media, but were universally slammed for dumping opening batsman Simon Katich at the age of 35 after he suffered an injury during the 2010-11 Ashes series.
His anointed replacement Phillip Hughes, 13 years his junior, failed to cement his place despite being handed multiple chances.
A litany of injuries has forced Harris to take time to accumulate his 19 test appearances, but his excellent form in the Ashes, as the leading wicket-taker in the northern series and 12 wickets Down Under, has justified selectors' patience with his fitness troubles.
Harris is still battling to recover from a knee injury but said his surgeon was "shocked" at how well he was progressing.
"I don't know what's going to happen with my knee," he said.
"I play every test like it's my last. I know the end is close but whether it's next week after the Melbourne test or whether it's in two years, I don't know."
Australia play England in the fourth test in Melbourne starting on December 26.
(Writing by Ian Ransom; Editing by Greg Stutchbury)
