Which events do we choose? In the first place, the event must be extraordinary. But there are many extraordinary happenings (., numerous stones dropping from the sky in Texas) that do not qualify as miracles. Why not? First, because they could be caused by something in nature, and second, because the context in which they occur is not religious. They qualify as mere oddities, as "strange happenings"; the sort of thing you might expect to read in Believe It or Not, but never hear about from the pulpit. Therefore the meaning of the event must also be religious to qualify as a miracle.
Suppose that a holy man had stood in the center of Houston and said: "My dear brothers and sisters! You are leading sinful lives! Look at yourselves—drunken! dissolute! God wants you to repent! And as a sign of his displeasure he's going to shower stones upon you!" Then, moments later—thunk! thunk! thunk!—the stones began to fall. The word "miracle" might very well spring to mind.
Not that we would have to believe in God after witnessing this event. But still, if that man in Texas seemed utterly genuine, and if his accusations hit home, made us think "He's right," then it would be very hard to consider what happened a deception or even an extraordinary coincidence.
This means that the setting of a supposed miracle is crucially important. Not just the physical setting, and not just the timing, but the personal setting is vital as well—the character and the message of the person to whom this event is specially tied. Take, for example, four or five miracles from the New Testament. Remove them completely from their context, from the teaching and character of Christ. Would it be wrong to see their religious significance as thereby greatly diminished? After all, to call some happening a miracle is to interpret it religiously. But to interpret it that way demands a context or setting which invites such interpretation. And part of this setting usually, though not always, involves a person whose moral authority is first recognized, and whose religious authority, which the miracle seems to confirm, is then acknowledged.
Abstract discussions of probability usually miss this factor. But setting does play a decisive role. Many years ago, at an otherwise dull convention, a distinguished philosopher explained why he had become a Christian. He said: "I picked up the New Testament with a view to judging it, to weighing its pros and cons. But as I began to read, I realized that I was the one being judged." Certainly he came to believe in the miracle-stories. But it was the character and teaching of Christ that led him to accept the things recounted there as genuine acts of God.
So there is not really a proof from miracles. If you see some event as a miracle, then the activity of God is seen in this event. There is a movement of the mind from this event to its proper interpretation as miraculous. And what gives impetus to that movement is not just the event by itself, but the many factors surrounding it which invite—or seem to demand—such interpretation.
But miraculous events exist. Indeed, there is massive, reliable testimony to them across many times, places and cultures.
Therefore their cause exists.