Why Astrology Is Pseudoscience-Paulthagard

Why Astrology Is a Pseudoscience

Paul R. Thagard

FROM P. Asquith and 1. Hacking, eds., Procceedings of the Philosophy of

Science Association Vol. 1 (East Lansing, Mich.: Philosophy of Science

Association, 1978), 223-34.

Most philosophers and historians of science agree

that astrology is a pseudoscience, but there is little

agreement on why it is a pseudoscience. Answers range

from matters of verifiability and falsifiability, to

questions of progress and Kuhnian normal science, to

the different sort of objections raised by a large panel of

scientists recently organized by The Humanist

magazine. Of course there are also Feyerabendian

anarchists and others who say that no demarcation of

science from pseudoscience is possible. However, I

shall propose a complex criterion for distinguishing

disciplines as pseudoscientific; this criterion is unlike

verificationist and falsificationist attempts in that it

introduces social and historical features as well as

logical ones.

I begin with a brief description of astrology. It

would be most unfair to evaluate astrology by reference

to the daily horoscopes found in newspapers and

popular magazines. These horoscopes deal only with

sun signs, whereas a full horoscope makes reference to

the "influences" also of the moon and the planets, while

also discussing the ascendant sign and other matters.

Astrology divides the sky into twelve regions,

represented by the familiar signs of the Zodiac:

Aquarius, Libra and so on. The sun sign represents the

part of the sky occupied by the sun at the time of birth.

For example, anyone born between September 23 and

October 22 is a Libran. The ascendant sign, often

assumed to be at least as important as the sun sign,

represents the part of the sky rising on the eastern

horizon at the time of birth, and therefore changes every

two hours. To determine this sign, accurate knowledge

of the time and place of birth is essential. The moon and

the planets (of which...