A prophecy is a religious prediction, often imparted by a god and recorded in a holy scripture.
Prophecy in the Bible
Prophecy as an argument for God
Theists often claim the fulfillment of prophecies as evidence for the existence of God. Such a claim, if substantiated, would indeed constitute evidence for the existence of something extraordinary, and possibly supernatural. However, a valid prophecy must meet several criteria:
- It must actually be a prophecy. Not a documentation of events that is misinterpreted as a prophecy after a similar event occurs later.
- It must be written before the events that it predicts.
- The predicted events must actually occur.
- The prediction must be both falsifiable and verifiable.
- It must not be overly vague.
- It must not predict a likely event.
- It must not be self-fulfilling.
A prophecy must be written before the events it predicts
This may seem obvious, but it is necessary. A passage like "And I saw two armies arrayed, and the northern army destroyed the southern one" might be a simple eyewitness report of a battle. But if it were discovered years after the event, it might be mistaken for a prophecy.
Similarly, the prophecy must not be altered after the fact. In the example above, a later editor might take World War II to be the fulfillment of the prophecy, and might alter the prophecy to read "And I saw Russian and German armies arrayed, and the Russian army conquered Germany". Since this second version was written after the events that it purports to predict, it cannot be considered a prophecy.
The prediction must be both falsifiable and verifiable
If a prophecy claims that world peace will be brought by someone, but then, when it does not occur, one can come back and make the claim that it never said it would happen in this world, it is unfalsifiable since there is no way, if a "next world" does not exist, to demonstrate that fact. An unverifiable prophecy would be one such as "Building X will be holy, and will represent the promise that a given war will never happen again". There is no observation that can be made either with human senses or scientific instruments that can demonstrate that. It is unverifiable.
The prophesied events must actually occur
Again, this requirement may seem too trivial to mention, but if the predicted events never occur, then the prophecy fails.
If the prophecy does not impose any time constraints on the prediction, then believers can, of course, claim that the prophecy has not yet been fulfilled.
The prophecy must not be overly vague
If a prediction is vague enough, then any number of events can match it. A prophecy like "Two powers shall strive, and an empire shall fall" could mean any number of things: two countries going to war, and one of them being defeated; or two countries going to war and destroying a third country; or even two supermarket chains competing for customers, and one of them going out of business.
If the prophecy is vague, and can apply to various situations, it becomes difficult or impossible to tell which one, if any, the prophet had in mind. This is to the prophet's advantage, since it becomes difficult to discredit him.
Anyone can predict that the sun will rise tomorrow, or that there will be a stock market crash, or an earthquake, or a war. These things happen fairly often, and predicting them does not require supernatural powers. Likewise, we can all extrapolate current events: if a hurricane is bearing down on Florida, it does not take a prophet to foresee that a town in its path might be destroyed.
A prophecy can be made less likely by adding details: "there will be an earthquake" is mundane. "San Francisco will be damaged by an earthquake within the next five years, in the summer" is much more impressive: the odds are very good that there will be an earthquake somewhere, at some point in the future, but the odds that San Francisco specifically will be affected, and in the time period and time of year specified, are much lower.
Additionally, it doesn't do justice to predict 7,000 events that each have a probability of 1/7,000 or even 1/20,000 under a naturalistic universe and then claim victory when one holds true. That is an example of the so-called multiple testing fallacy.
A self-fulfilling prophecy is one that contains the seeds of its fulfillment. Perhaps the best-known one is the tragedy of Oedipus: the delphic oracle's prophecy that Oedipus would kill his father and marry his mother set in motion a sequence of events that resulted in the prophecy coming true.
The May 26, 2007 episode of The Non-Prophets began with a "prophecy" that in 2007, there would be a radio show in Austin, hosted by Denis Loubet and Matt Dillahunty. If such a prophecy had actually appeared in a holy book, and people wanted it to come true, then no doubt there would today be many people named Denis and Matt, and many towns called Austin, named by people trying to make the prophecy come true.
The Bible (specifically Daniel) predicts that the nation of Israel would be reborn, and its creation in 1948 is often taken as the fulfillment of that prophecy. But of course this happened because people worked to make it happen, in part because of the prophecy. Most scholars believe the Israel that was "predicted" (Daniel was written after the fact) was the Israel created under the Maccabees.