God has revealed himself to a select few in recorded and oral history. Do miracles occur? Absolutely. This is doctrine.
In “testing” for miracles one come dangerously close to approaching a desire for the scientific proof of God. This will never happen. He that is above and beyond all that exists requires faith for salvation. Scientific “proof” reduces God to science and eliminates faith.
He will come again and all will see and science will have no meaning.
This is not exactly a Catholic understanding (though it is one that many in the Protestant tradition would affirm).
Actually, it is a *de fide *teaching of the Church that the existence of God is knowable through natural reason, and hence, God’s existence is a kind of scientific knowledge. It is not, however, an empirical sceince (dealing only with matter), but rather belongs to the science of philosophy (the most important of the natural sciences). To accept God’s existence does not require faith necessarily. Faith involves accepting certain propositions which we cannot independently prove on God’s on authority as being revealed. Hence, anything that we can prove through natural reason does not necessarily require faith (though it can involve faith for those who do not understand the proofs).
That being said,
TheAtheist asks what is a miracle? A miracle is a supernatural intervention in the natural world. Can miracles be scientifically tested? Most certainly. Essentially a miracle could have no known/possible scienfic explanation, and so when a supposed miracle occurs, the Church has experts in the sciences come and investigate the claims to see if some possible explanation can be found.
People speak of miracles very loosely these days (and I suppose have always done so), which might only help to add confusion. People say, “Oh, it was a miracle that I found this job, etc” technically speaking, these kinds of these have natural explanations and are not technically miracles. Although they may be from God (and hence part of God’s Divine Providence), they are not actually supernatural interventions (which alter the manner in which the natural laws would normally proceed).
How does one determine causality? Let me give an example that one of my Theology professors gave to me. Say for instance that teh desk in my room began to float in the air. Is this a miracle? I don’t know yet. I feel under the desk to make sure nothing is pushing it up, and I feel over the desk to make sure nothing is suspending it. I bring in equipment to determine if there are any strong magnetif feilds at work that could accomplish such a feat. I test and I test, and consult experts, and still can find nothing. Do I now conclude this is a miracle? If I had no other information, I would most certainly not make this conclusion. Unexplained phenomena do not a miracle make. A miracle is supposed to be a sign which proves the validity of a certain message. So, if before the desk started to float, I heard a voice that sounded like God say “Give your next paycheck to the poor.” Then I might conclude that the dest floating was a miracle sent from God to prove that the message was really from Him.
The entire purpose of miracles is to provide us with proof, so to say that one woudl not test them, is contrary to the very nature of miracles.