Jesus is not asking whether their eyes and ears work. They did. That is the point. They had seen the loaves multiply and heard His teaching, yet they were acting as though none of it had happened. Gill puts it this way: "they had bodily eyes, and with them saw the miracles he wrought, and yet took little notice of them."

The last question, "do ye not remember?", turns from seeing to memory. It sets up the two questions that follow, about the baskets of fragments (Mark 8:19-20). Gill suggests they had let slip both His explanations of the parables and the miracles of the loaves.

The disciples say nothing to these questions directly, but Jesus immediately tests their memory. When He asks about the five loaves, "They say unto him, Twelve" (Mark 8:19). When He asks about the seven, "they said, Seven" (Mark 8:20). They remembered the numbers exactly. What they had not grasped was what the numbers meant, so Jesus asks, "How is it that ye do not understand?" (Mark 8:21).

Jesus' words echo the language of the prophets. Jeremiah called Judah a "foolish people, and without understanding; which have eyes, and see not; which have ears, and hear not" (Jeremiah 5:21). Earlier in Mark, Jesus had used similar words about "them that are without," who would see and not perceive, hear and not understand (Mark 4:11-12).

In Bible language, to "see" and "hear" often means to take something in and respond to it, not just to notice it. Gill thinks the question perhaps means both kinds of eyes: the eyes of their understanding had been enlightened by Christ, "and yet saw things but very darkly."

These questions show Jesus refusing to let His closest friends drift into the blindness of outsiders. In Mark 4:11-12 the language of seeing without perceiving described those outside. Now Jesus asks it of His own disciples. Being in the boat with Him did not by itself mean seeing what He was showing.

Mark places a healing right after these questions. A blind man at Bethsaida receives his sight in two stages: first he sees "men as trees, walking," then "every man clearly" (Mark 8:24-25). Matthew Henry sees in that cure a picture of how Christ heals those who are spiritually blind: "at first, their knowledge is confused." The disciples are partway there, and Jesus is not finished with them.