The removal of pluto from the class of planets and homosexuality from the class of psychiatric disorders: a comparison

The controversies over psychiatric classification in the past 30 years have garnered considerable attention. The existence of rancorous debates about how to classify is associated with claims that the developers of psychiatric diagnostic systems inappropriately clothe themselves in the aura of science without being scientific [1,2]. Although this article will not solve the problem of what counts as a "legitimate" scientific approach, it will make some claims about the role of debate between competing perspectives in the process of developing scientific classifications.The purpose of the article is to draw comparisons between two different, yet surprisingly similar controversies, namely, whether Pluto is a planet and whether homosexuality is a psychiatric disorder. In our opinion a compelling argument can be made that Pluto never should have been classified as a planet to begin with and that homosexuality never should have been labeled a psychiatric disorder, and that the decisions to re-classify them were correct.Let us discuss Pluto first. Pluto's existence and location was predicted by Percival Lowell based on discrepancies between the observed and predicted orbit for Uranus. Astronomers, however, made a mistake when predicting the orbit of Uranus. In their calculations they plugged in an incorrect size for Neptune's mass. If they had plugged in the correct size, the difference between the predicted and the observed orbits of Uranus would not have been so great [3]. It was mere accident that in 1930 Clyde Tombaugh, the discoverer of Pluto, found an object where Lowell said it should be.With respect to homosexuality, in the late 19th century there were active debates about whether same-sex attraction was a vice, a medical condition, or a harmless variation in behavior [4]. Its inclusion in psychiatric taxonomies was initially related to the scientifically discredited assumptions of degeneration theory - which began life as a theological concept but was naturalized