What makes a Catholic miracle true?

Answer 1

The web definition of miracle is: "a surprising and welcome event that is not explicable by natural or scientific laws and is therefore considered to be the work of a divine agency." What makes it true is God. If you are asking what makes it true to us, then it is the witness of the Church. The greatest Catholic miracle, be very definition, is the rising of Jesus from the grave; which is true from the power of God, and is witnessed by the members of the Church and history.

from Modern Catholic Dictionary by John A. Hardon, S.J. Doubleday & Co., Inc. Garden City, NY 1980

Miracle. A sensibly perceptible effect, surpassing at least the powers of visible nature, produced by God to witness to some truth or testify to someone's sanctity.

Answer 2

The Catholic Church accepts a miracle as true if there is no apparent natural cause. Claims of miraculous cures are first attested by doctors to say that the cure can not be explained by natural science.

The great British philosopher David Hume (1711-1776) deals with the broader perspective of whether Catholic miracles, or indeed any miracles, are true. He says (Enquiry Concerning Human Understanding, Of Miracles):

1. History does not provide us with cases of miracles that are attested to by a sufficient number of credible witnesses. Neither have they occurred in circumstances where all doubt as to fraud can be ruled out.
2. Human beings are naturally credulous because they find it agreeable to hear and relate remarkable stories.
3. The testimony for miracles that favour one system of religion is contradicted by the testimony for miracles favouring others.

Many of the most awe-inspiring Catholic miracles are said to have occurred in late antiquity or during the Dark Ages. Once again, David Hume says that reports of miracles become less and less frequent as we approach the enlightened ages.