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Monday, 16 April 2012

The Principle of the Excluded Middle

Aristotle (right, as imagined by Rembrandt) is often blamed for the prevalence of black-and-white thinking in Western culture. But the problem stems not from what Aristotle said, but what people think he said. The Principle of the Excluded Middle, as originally formulated by Aristotle himself, makes perfect sense. It argues that, if a statement X is demonstrated to be false, then the negation of statement X must necessarily be true. The operative word is ‘negation’... not ‘opposite’.

I mentioned the Bible’s Excluded Middle on a previous occasion. If you start with statement X = ‘Everything in the Bible is true’, and find something in the Bible that is demonstrably false, then you have proved that statement X is false. All this means, in strictly Aristotelian terms, is that the negation of X must be true: ‘Not everything in the Bible is true’. But far too many people imagine they have proved the opposite of X to be true: ‘Everything in the Bible is false’. It’s not just the Bible-hating atheists who take this view -- many Biblical literalists do as well. That’s why they get so upset if anyone suggests that pi is anything other than three.

For a more Fortean example, there is an analogous situation in the case of UFOs. In this case, statement X might be ‘All UFO reports can be attributed to sightings of extraterrestrial spacecraft’. If this statement is proved to be false, then all the Excluded Middle says is that its negation must be true: ‘Not all UFO reports can be attributed to sightings of extraterrestrial spacecraft’. But again there is a tendency to apply the erroneous logic that the opposite statement must be true: ‘No UFO reports can be attributed to sightings of extraterrestrial spacecraft’. And again, it’s not just the skeptics who think along these lines, but the UFO enthusiasts as well... hence their outrage when any specific report is ‘explained away’ as a weather balloon, the planet Venus or a flock of pelicans.

When Aristotle formulated his Principle of the Excluded Middle, he was talking about a statement and its negation, not a statement and its opposite. But the ancient Greek philosophers did have something to say on the latter subject. It’s called the Dialectic Principle, and in this case the statement is called the ‘thesis’ and its opposite is called the ‘antithesis’. According to the Dialectic Principle, the two sides should engage in a sober and rational dialogue, and come to some mutually agreed compromise called a ‘synthesis’ (don’t laugh -- the ancient Greeks really thought this might happen).

In the case of ufology, the thesis would be ‘All UFO reports can be attributed to sightings of extraterrestrial spacecraft’ and the antithesis would be ‘All UFO reports have mundane explanations’. If ufologists and skeptics were as enlightened as the ancient Greek philosophers, they would engage in a meaningful dialogue—without spelling mistakes, bad grammar and whole sentences in capital letters—and come to a synthesis from which the state of human knowledge could move forward. But the real world doesn’t work like that.

Forteans, of course, are an exception to the general rule -- we are at our most comfortable in the ‘excluded middle’ between thesis and antithesis. Charles Fort himself referred to the dialectic principle in Lo!, and even attributed it to Aristotle: “I am thinking of an abstraction that was noted by Aristotle, and that was taken by Hegel for the basis of his philosophy: That wherever there is a conflict of extremes, there is an outcome that is not absolute victory on either side, but is a compromise, or what Hegel called the union of complementaries.”

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