What does John 19:4 mean?

Pilate is not stupid. He's seen enough to know that Jesus' message is not an immediate threat to Roman rule (John 18:36–38). He can also tell Jewish religious leaders are pursuing a personal vendetta (Matthew 27:18). However, they've also brought an agitated crowd (Matthew 27:20–23). History tells us Pilate's governorship was strained. He was criticized for brutal tactics, and deliberately antagonizing the Jewish people. At this point, he was likely under a strict warning that major unrest would result in losing his position. Rather than simply tell the mob to disperse, Pilate is looking for middle ground.

Even though the Jewish leaders want Jesus killed, Pilate would prefer not to do their dirty work for them. Having Jesus brutally whipped and humiliated, awful as it is, seems to be Pilate's attempt to spare Jesus' life. Now, he prepares to present a maimed, mocked, and apparently defeated Jesus to the crowd. In a modern setting, his words might have been, "take a look, now, and see how much I've already done to an innocent man."

The meaning of Pilate's declaration is really a question: "isn't this enough?" As John's account continues, we see the mob settle for nothing less than death.