The distinction between ideas and activities that represent science and those that represent nonscience is usually clear; no one confuses physics with art or chemistry with poetry. Nevertheless, there are ideas and activities related to bodies of knowledge that are not characterized clearly as science or nonscience and sometimes are claimed by their proponents to be science but are considered by most scientists to be pseudoscience. For example, the National Science Foundation (2002) conducted a poll on the different forms of pseudoscience accepted by Americans:

• Thirty percent believe that unidentified flying objects (UFOs) are space vehicles from other civilizations.
• Sixty percent believe in extrasensory perception (ESP).
• Forty percent think astrology is scientific.
• Thirty-two percent believe in lucky numbers.
• Seventy percent accept magnetic therapy as scientific.
• Eighty-eight percent agree that alternative medicine is a viable means of treating illness.

Most scientists reject these beliefs, which are variously called pseudoscience, voodoo...