Pseudomathematics

One common type of approach is claiming to have solved classical problems which have been proved to be mathematically impossible. Common examples of this include the following constructions in Euclidean geometry—using only compass and straightedge:

• Squaring the circle: Given any circle drawing a square having the same area.
• Doubling the cube: Given any cube drawing a cube with twice its volume.
• Trisecting the angle: Given any angle dividing it into three smaller angles all of the same size.[4][5][6]

For more than 2,000 years, many people had tried and failed to find such constructions; in the 19th century, they were all proven impossible.[7][8]^:47

Another common approach is to misapprehend standard mathematical methods, and to insist that the use or knowledge of higher mathematics is somehow cheating or misleading (e.g., the denial of Cantor's diagonal argument[9]^:40ff and Gödel's incompleteness theorems).[9]^:167ff[1]

The term pseudomath was coined by the logician Augustus De Morgan, discoverer of De Morgan's laws, in his A Budget of Paradoxes (1915). De Morgan wrote:

The pseudomath is a person who handles mathematics as the monkey handled the razor. The creature tried to shave himself as he had seen his master do; but, not having any notion of the angle at which the razor was to be held, he cut his own throat. He never tried a second time, poor animal! but the pseudomath keeps on at his work, proclaims himself clean-shaved, and all the rest of the world hairy.[10]

De Morgan gave as example of a pseudomath a certain James Smith who claimed persistently to have proved that π is exactly 3+1/8.[3] Of Smith, De Morgan wrote: "He is beyond a doubt the ablest head at unreasoning, and the greatest hand at writing it, of all who have tried in our day to attach their names to an error."[10] The term pseudomath was adopted later by Tobias Dantzig.[11] Dantzig observed:

With the advent of modern times, there was an unprecedented increase in pseudomathematical activity. During the 18th century, all scientific academies of Europe saw themselves besieged by circle-squarers, trisectors, duplicators, and perpetuum mobile designers, loudly clamoring for recognition of their epoch-making achievements. In the second half of that century, the nuisance had become so unbearable that, one by one, the academies were forced to discontinue the examination of the proposed solutions.[11]

The term pseudomathematics has been applied to attempts in mental and social sciences to quantify the effects of what is typically considered to be qualitative.[12] More recently, the same term has been applied to creationist attempts to refute the theory of evolution, by way of spurious arguments purportedly based in probability or complexity theory.[13][14]

• 0.999... often claimed to be distinct from 1
• Indiana Pi Bill
• Eccentricity (behavior)
• Invalid proof
• Pseudoscience
• Recreational mathematics

• Underwood Dudley (1987), A Budget of Trisections, Springer Science+Business Media. ISBN 978-1-4612-6430-9. Revised and reissued in 1996 as The Trisectors, Mathematical Association of America. ISBN 0-88385-514-3.
• Underwood Dudley (1997), Numerology: Or, What Pythagoras Wrought, Mathematical Association of America. ISBN 0-88385-524-0.
• Clifford Pickover (1999), Strange Brains and Genius, Quill. ISBN 0-688-16894-9.
• Bailey, David H.; Borwein, Jonathan M.; de Prado, Marcos López; Zhu, Qiji Jim (2014). "Pseudo-Mathematics and Financial Charlatanism: The Effects of Backtest Overfitting on Out-of-Sample Performance" (PDF). Notices of the AMS. 61 (5): 458–471. doi:10.1090/noti1105.