The two former Premier League footballers and current Sky Sports pundits were discussing the 63-year-old after comments he made during a pre-match press conference on Friday afternoon.
"It's not good enough," Van Gaal told reporters, discussing his side's recent form. "But on the other hand, we are in a process, as I have said from the beginning.
"The process shall take more than one year; it shall take three years."
And former United defender Neville feels the Dutchman is being 'sensible.'
Ex-Liverpool man Carragher, however, took a more sceptical stance, questioning Van Gaal's sudden change of stance after earlier claiming he should be judged after three months.
Just seen LVG quotes it will take 3 yrs. I think that's sensible and he will get it right.United will win the league under him I'm convinced— Gary Neville (@GNev2) November 7, 2014
@Carra23 he said things will improve after 3 months.He has said today he will win PL after 3 years Mr Carragher. Dec 14th it will come right— Gary Neville (@GNev2) November 7, 2014
Man United host Crystal Palace tomorrow afternoon having not won for over a month.
Those who side with Neville believe the Dutchman's firm approach will restore the Old Trafford outfit to their former heights. Those who agree with Liverpool legend Carragher, though, are less than impressed with his constant chatter about 'philosophy' and failure to deliver any actual results thus far.