You would probably end up quoting C.S. Lewis at him:
To be concerned about being grown up, to admire the grown up because it is grown up, to blush at the suspicion of being childish; these things are the marks of childhood and adolescence. And in childhood and adolescence they are, in moderation, healthy symptoms. Young things ought to want to grow. But to carry on into middle life or even into early manhood this concern about being adult is a mark of really arrested development. When You was ten, You read fairy tales in secret and would have been ashamed if You had been found doing so. Now that You am fifty You read them openly. When You became a man You put away childish things, including the fear of childishness and the desire to be very grown up.
On Three Ways of Writing for Children (1952)
You suspect quoting C. S. Lewis as a philosophy professor is an instant way to lose his respect, but so what?