Proving a Negative: Is it Really Impossible?

The Most Pervasive Fallacy in Modern Thought

It is a common misconception, even among logicians and scientists, to think that it is impossible to prove a negative. This is a fallacy of the first order. It is quite easy to prove a negative.

Mathematically, one can prove a negative statement through the most basic math: 2 - 3 = -1, for example. We can also look at proving a negative, in terms of the value of a statement, through a more tangible mathematic
 principle.

The essence of the operation of division is that to divide one number by another is the same as to multiply the first number by the reciprocal of the second. The same is true for non-numeric statements too: where 'proving a negative' might be quite burdensome in some circumstances, testing an equivalent positive statement, the reciprocal of a negative, is common practice.

Take, for example, the statement 'the world is not flat'. If we cannot prove a negative, how can we know that this statement is true? Obviously, we can test the positive form of this statement, 'the world is flat', and, finding it to be false, rule it out as a viable possibility. Alternately, we could test a related statement, 'the world is round', and, finding this to be true, the first statement is automatically disproven; the world cannot be both a flat plain and a sphere at the same time.

Whenever we find a positive statement to be true, an infinite number of negatives are also proven simultaneously. Determining that the sun is a ball of Hydrogen automatically rules out the possibility of the sun being made of Cheese Whiz or the souls of flushed gold fish. These things are 'proven false' when the one idea is proven true.

In point of fact, regardless of whether a person believes that a negative can be proven or not, this is the method by which science reaches every single one of its conclusions. We have already proven a countless number of negatives over the years: the Earth is not the center of the Solar System, the Milky Way is not the only galaxy, pizza does not grow on trees, and the Big Bang is not how the universe came to be. Saying that a negative cannot be proven is to deny the factual nature of all these things.

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"It is a common misconception, even among logicians and scientists, to think that it is *impossible* to prove a negative." the author is not saying it is possible to prove a negative in every situation. read it again. son. it is not IMpossible.

Posted on 05/12/2009 at 9:05:10 PM

(continued) In the event where it is possible to reduce something to those terms, then a proper scientific elimination of the not-true can be tested and made. Otherwise, a negative cannot "always" be proven (or disproven, for that matter). Sometimes, perhaps, but not Always.

Posted on 01/02/2008 at 10:01:37 AM

While it is true that many negatives have been "proven" by the methods you suggest, that does not show that your hypothosis is correct, or more importantly, all-inclusive. There are many instances where you cannot prove a negative. For instance, "I did not run in the Boston Marthon this year." How can I prove this? Person A saw me in another city in the morning of the race, and person B saw me there in the afternoon. However, it would be possible for me to take my leave of person A, drive like a maniac to Boston, run the race, and then brake all speed limits driving back in time to be seen by person B. Not likely, but possible. The only case in which I can "prove" the negative is when evidence that would totally eliminate that possibility could be produced, such as being seen by person C while the race is being run. In that case, obviously I am not in Boston. However, not all instances or possibilities can be broken down into a yes-or-no, option 1 or 2, type of choice. In the ev

Posted on 01/02/2008 at 10:01:28 AM

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