Skeptikkojen haasteet

Skeptikkojen haasteita vastaan on esitetty kaksi perusargumenttia: 1) Jos joku voittaa haasteen, skeptikot saattavat riitauttaa asian, jotteivat joutuisi maksamaan ja 2) Haasteeseen osallistumisen kustannukset (esimerkiksi testikulut) saattavat tulla kalliimmaksi kuin itse voittosumma.

Tässä on hyvä esimerkki, miten tämän tyyppiseen haasteeseen vastaamisessa saattaisi käydä. Spiritualisti ja tiedemies Alfred Russel Wallace vastasi haasteeseen, jossa piti todistaa Maan kaarevuus. Se onnistui, mutta lopulta kaikkien käänteiden jälkeen koko homma maksoikin Wallacelle enemmän kuin tuotti ja aiheutti enemmänkin mielipahaa.

"In 1870, a Flat-Earth proponent named John Hampden offered a £500 wager (equivalent to about £42000 in present-day terms[147]) in a magazine advertisement to anyone who could demonstrate a convex curvature in a body of water such as a river, canal, or lake. Wallace, intrigued by the challenge and short of money at the time, designed an experiment in which he set up two objects along a six-mile (10 km) stretch of canal. Both objects were at the same height above the water, and he mounted a telescope on a bridge at the same height above the water as well. When seen through the telescope, one object appeared higher than the other, showing the curvature of the earth.

The judge for the wager, the editor of Field magazine, declared Wallace the winner, but Hampden refused to accept the result. He sued Wallace and launched a campaign, which persisted for several years, of writing letters to various publications and to organisations of which Wallace was a member denouncing him as a swindler and a thief. Wallace won multiple libel suits against Hampden, but the resulting litigation cost Wallace more than the amount of the wager and the controversy frustrated him for years."