First, some linguistic terminology and notations need to be introduced. Phonetic transcription (representing each distinct speech sound with a separate symbol) is shown with the IPA enclosed in square brackets [ ], and phonemic transcription (representing a small set of speech sounds that a particular language distinguishes) is enclosed within virgules or forward slashes / /. In articulatory phonetics, "aspiration" is an articulation that involves an audible release of breath. For example, the /t/ in tore [tʰɔər] is "aspirated" with a noticeable puff of breath, but the /t/ in store [stɔər] is "unaspirated." The IPA diacritic for aspiration (the word deriving from the Roman name for a Greek "rough breathing" diacritic, spiritus asper) is a superscript "h", [ʰ] (e.g., tʰ dʰ), and normal unaspirated consonants are not explicitly marked. "Voice" or "voicing" distinguishes whether a particular sound is either "voiced" (when the vocal cords vibrate) or "unvoiced" (when they do not). Examples of IPA phonation diacritics include voiceless , voiced , breathy voiced , and creaky voiced .
The initial Chinese sound, a tenuis unvoiced alveolar plosive represented by the IPA symbol [t̥], exists in English -- but never as an initial. You can find it instead in words such as "stop" or "pat". An initial t, as in "tap", is in English pronounced as /tʰ/ -- that is, an aspirated version of Ḍ [t], its complementary allophone. The natural English pronunciation of the word spelled Tao is therefore /tʰaυ/. In standard Mandarin phonology, however, [t̥] and [tʰ] are not allophonic, but represent two distinct phonemes. In fact, [tʰaυ] does not merely sound wrong, it sounds like a different word -- 桃 [tʰaυ] "peach", or 套 [tʰaυ] "cover" (distinguished by tone contour).
The alternative English spelling, Dao, results in another mispronunciation, /daυ/. The initial consonant is [d], a voiced alveolar plosive. However, [d] is not a phoneme in Mandarin, which has no voiced plosives, therefore the initial voicing of [daυ] is not significant to the Chinese listener. What is significant is that, unlike the English [t], [d] is not aspirated in word-initial position. Therefore the English-speaker's /daυ/ seems more similar to the desired Chinese [t̥aυ] than the alternative /tʰaυ/, even though both are technically equally incorrect, one because of voicing, the other because of aspiration. Only the aspiration error is phonemically important to the Chinese listener.
The linguist Michael Carr explains:
The provenance of the pronunciation with [t] of Taoism is a gap in the English phonemic paradigm for the unvoiced unaspirated [t̥] in dào [t̥au] 'way'. This Chinese /t̥/ phoneme is nearer to the pronunciation of English voiced unaspirated /d/ in Dow than the voiceless aspirated /t/ in Taos, but it is neither. The Chinese aspirated vs. non-aspirated phonemic contrast is almost the opposite of the English voiced vs. unvoiced contrast. In certain positions, English non-aspirated consonants can occur as variants of aspirated ones. Stops after initials [s-] in English *e.g., spy, sty, sky) are unvoiced unaspirated and close to the /t̥/ phoneme in [t̥au] 'way', but these are not highly voiced, and the English distinction can be analyzed as one of aspiration, with voicing redundant and predictable. (1990:60)
Since the great majority of people who first attempted to transcribe Chinese were not linguists (and even if they were, the principles of modern phonemics were not discovered for another two centuries), their endeavour was marred by a lack of systematic approach and many contemporary European misconceptions about language. Even more than two hundred years later, during the last century, when Western specialists in Chinese, who had by that time created the discipline known as sinology, designed the early forms of numerous transcriptions used today, the first mistakes of enthusiastic missionaries, envoys and business men were not fully eliminated. In fact their traces can be seen even today. (1968:50-51)
There are numerous rival systems for the Romanization of Chinese for Standard Mandarin pronunciation. Compare these transcriptions of Chinese 道 [t̥aυ]: Wade-Giles tao or tao4 (marking 4th tone), Legge romanization tâo, Latinxua Sin Wenz dau, Yale Romanization dàu, Mandarin Phonetic Symbols II dau, Hanyu Pinyin dào, Tongyong Pinyin daˋo, Gwoyeu Romatzyh or National Romanization daw, Zhuyin fuhao ㄉㄠ, and Cyrillic Palliday system дао.
Romanization systems use one of two arbitrary ways to represent the Chinese phonemic opposition between aspirated and unaspirated consonants. Take for example, Chinese unaspirated 道 [t̥aυ] "way" and aspirated 桃 [tʰaυ] "peach". Some systems, like Wade-Giles tao 道 and t'ao 桃, introduce a special symbol for aspiration; others, like Pinyin dao 道 and tao 桃, use "d" and "t". In English and other languages, "d" and "t" indicate a voiced and unvoiced distinction, which is not phonemic in Chinese.
From a theoretical perspective, both tao and dao transliterations if pronounced according to English spelling conventions are equally close to, or far from, the Standard Mandarin pronunciation of 道 [t̥aυ]. However in practice, most English speakers think the Chinese pronunciation sounds more like an English initial /d/ than an English initial /t/ because the Chinese pronunciation is unaspirated. Therefore, some argue that Dao is in that sense more "accurate" than Tao.
An inherent problem with the arcane Wade-Giles use of apostrophes to differentiate aspiration is that many English readers do not understand it, which has resulted in the frequent mispronunciation of Taoism as [taυizəm] instead of [daυizəm]. Alan Watts (1975:xix) explains using Wade-Giles "in spite of its defects" but writes: "No uninitiated English-speaking person could guess how to pronounce it, and I have even thought, in a jocularly malicious state of mind, that Professors Wade and Giles invented it so as to erect a barrier between profane and illiterate people and true scholars."
According to the Oxford English Dictionary (2nd ed.), the first recorded occurrences of the relevant words were Tao 1736, Tau 1747, Taouism and Taouist 1838, Taoistic 1856, Tao-ism 1858, Taoism 1903 [clearly wrong, at least antedated by Balfour (1881)], Daoism 1948, Dao and Daoist 1971.
Carr (1990:66) contrasts the English pronunciations of gung-ho and kung-fu to differentiate borrowings deriving from spoken and written Chinese. The OED records the first usage of gung-ho in 1942 (referring to Evans Carlson's Marines) and of kung-fu in 1966 (referring to Bruce Lee's movies). Gung-ho (Pinyin gōnghé 工合 "work together", see Cohen 1989) is more "correctly" pronounced [ɡʌŋhou] because it was first imported from spoken rather than written Chinese. Nevertheless, many English speakers read the Wade-Giles kung-ho as [kʌŋhou] (the OED gives "kung-hou" [sic]). Kung-fu (Pinyin gōngfú 功夫 "ability", meaning "Chinese martial arts") is commonly mispronounced [kʌŋfuː] instead of [gʌŋfuː] owing to confusion over Wade-Giles romanization of unaspirated k [g] vs. aspirated k' [k].
Many Anglo-Chinese borrowings besides Taoism are mispronounced because of romanization. A commonly heard example is the Yijing [ïdʒiŋ] "Book of Changes" which, owing to Wade-Giles "I Ching," is usually cacologized as [aɪtʃiŋ] taking yi 'change; easy' in false analogy (ego?) with English I. In most cases, Pinyin romanization more accurately represents Chinese pronunciations than Wade-Giles; English speakers would read the martial art "Tai Ji Quan" closer to tàijíquán [taitʃitʃʰuan] 'great ultimate fist' than "T'ai Chi Ch'üan." (Carr 1990:67-8)
More generations of English speakers have learned about China through Wade-Giles (proposed in 1859, revised in 1892) than through Pinyin (approved in 1958, adopted in 1979). The English word Taoism is unquestionably older and more familiar than Daoism. However, in academia and international politics, there have been continuous trends towards adopting pinyin, which is widely used in the Western study of the Chinese language and official in the People's Republic of China. Hanyu Pinyin has become the international standard for Chinese romanization, used by the United Nations, the International Organization for Standardization (ISO 7098), and similar associations.
While sinologists increasingly prefer the term Daoism, traditionalists continue using the well-known Taoism. Some scholars consciously adopt "Daoism" in order to distinguish the Chinese philosophy and religion from what "Taoism" embodied in the 19th- and 20th-century Western imaginations. Girardot, Miller and Liu (2001: xxxi) explain, "earlier discussions of the Daoist tradition were often distorted and misleading - especially in terms of the special Western fascination with the 'classical' or 'philosophical' Daode jing and the denigration and neglect of the later sectarian traditions."
Carr analyzes how English dictionaries gloss Taoism's pronunciation, comparing 12 published in Great Britain (1933-1989) and 11 published in the United States (1948-1987).
Pronunciations are given in various dictionary respelling systems, rather than IPA, but for purposes of discussion, they are divisible into four types: [daυɪzəm], , , and [taυɪzəm]. The first is strictly "correct," the second and third are partially so, depending upon descriptive/prescriptive policies, and the last is inaccurate. Since many, if not most, English speakers pronounce Taoism as [taυɪzəm], it can legitimately be listed as an alternate. Dictionaries are justified in glossing if they follow a convention of giving preferred pronunciation first, or as if they give common pronunciation first (and if they have some way to determine this). (1990:64)Within Carr's sample, most American dictionaries gloss , while most British ones gloss [taυɪzəm] and have been slower to add the [daυɪzəm] rectification. The respective first accurate glosses for Taoism were "douizm; tou-" (Webster's International Dictionary of the English Language, 2nd ed., 1934) and "Also Daoism and with pronunc. (dau•iz'm)" (Oxford English Dictionary Supplement, 1986).
First, publishing houses have profit concerns about changing romanizations of foreign books. There are more English translations titled Tao Te Ching than Dao De Jing, seeing as it is more familiar to native speakers. However, some academic publishers have abandoned Wade-Giles in favor of pinyin; Columbia University Press changed the titles of Burton Watson's translations from "Chuang Tzu" to "Zhuangzi" and from "Han Fei Tzu" to "Hanfeizi".
Second, libraries have independent concerns about revising legacy Wade-Giles catalogs to contemporary pinyin. After the Library of Congress converted to pinyin in 1997, librarian Jiajian Hu (1999:250-1) listed three reasons why they deemed Wade-Giles unsatisfactory and added four more.