Actual ambiguity refers to ambiguity that occurs in the act of speaking. It arises when a word or phrase, without variation either in itself or in the way the word is put forward, has different meanings. The statement does not contain adequate information to resolve the ambiguity, resulting in a number of legitimate interpretations. Two distinct types of ambiguity are categorised as actual ambiguity: pragmatic and extraneous.
Pragmatic ambiguity arises when the statement is not specific, and the context does not provide the information needed to clarify the statement. Information is missing, and must be inferred. An example of pragmatic ambiguity is the story of King Croesus and the Oracle of Delphi (adapted from Copi and Cohen 1990):
"King Croesus consulted the Oracle of Delphi before warring with Cyrus of Persia. The Oracle replied that, "If Croesus went to war with Cyrus, he would destroy a mighty kingdom". Delighted, Croesus attacked Persia, and Croesus’ army and kingdom were crushed. Croesus complained bitterly to the Oracle’s priests, who replied that the Oracle had been entirely right. By going to war with Persia, Croesus had destroyed a mighty kingdom – his own."
Pragmatic ambiguity arises when the statement is not specific, and the context does not provide the information needed to clarify the statement (Walton 1996). The information necessary to clearly understand the message is omitted. Due to the need to infer the missing information, pragmatically ambiguous statements have multiple possible interpretations (Walton 1996). Croesus interpreted the Oracle’s statement as indicating his success in battle – the response he desired. As noted by Hamblin (1970), Croesus’ logical response to the oracular reply would have been to immediately ask the Oracle, "Which kingdom?" Further information is needed to resolve pragmatic ambiguity.
In the case of an information request, pragmatic ambiguity exists in the request for "A report of all the clients for a department." The ambiguity is that the request does not refer to a specific department. The end user could legitimately prepare a report for any department. Further information is needed to resolve this actual ambiguity in this case.
In contrast to pragmatic ambiguity, in which information necessary to clearly understand the message is omitted, extraneous ambiguity arises from an excess of information. Clearer communication arises where the minimally sufficient words needed to convey the message of the statement are used (Fowler and Aaron 1998). Where more words are used than necessary, or where unnecessary detail is provided in the communication that is not part of the message, ambiguity arises. The excess detail obscures the essential message and contributes to different emphases or interpretations.
The use of passive voice, vacuous words, or the repetition of phrases with the same meaning all contribute to lack of clarity (Fowler and Aaron 1998). The use of clichés and the over-use of figures of speech add volume to the statement, but add little or no meaning. Pretentious and indirect writing also adds to the bulk of the statement, but without adding meaning. Fowler and Aaron (1998) provide the following comparative example:
- Pretentious: To perpetuate our endeavour of providing funds for our elderly citizens as we do at the present moment, we will face the exigency of enhanced contributions from all our citizens.
- Revised: We cannot continue to fund Social Security and Medicare for the elderly unless we raise taxes.
The extra volume contributes to vagueness in the first statement, and adds to the multiplicity of legitimate interpretations of the statement. The first statement exhibits extraneous ambiguity. The second statement communicates forcefully and concisely.
An example of extraneous ambiguity in an information request is "A report of all clients (and their names and addresses only) for the Tax and Business Services department. Some of those clients are our biggest earners, you know". The last sentence is extraneous, and contains detail that is redundant, uninformative, or misleading relative to the fundamental message. In information theoretic terms, extraneous ambiguity is "noise" in the communication (Axley 1984; Eisenberg and Phillips 1991; Severin and Tankard 1997).