Ambivalent - ambiguous
Be careful to distinguish the adjectives ambivalent and ambiguous. In particular, do not use ambiguous when the correct word is ambivalent. It is sometimes easy to confuse the two words because there are situations in which both may be appropriate – though, strictly, each will apply to a different aspect of the situation.
Ambivalent - the related noun is ambivalence - applies to attitudes, feelings, emotions and the like, and means ‘opposed, conflicting’. (The word comes from the Latin ambi-, the combining form of the numeral ambo, ‘both’, ‘two’, and valēre, ‘to be worth’.) An ambivalent attitude towards a person or situation is an attitude in which there are opposed or conflicting elements (e.g., approval and disapproval; joy and sadness). If I both welcome (some aspects of) the local authority’s plans for a new housing development but am opposed to (other aspects of) it, my attitude to the proposal is ambivalent. The following couplet by the Roman poet Catullus (c84-54 BCE) is an (unambiguous) statement of his ambivalent feelings about his mistress Lesbia:
I love and hate. Why, you perhaps ask, do I do this?/I do not know, but I feel it, and am in torment.
(Odi et amo. Quare id faciam, fortasse requiris?/Nescio, sed fieri sentio, et excrucior.)
Ambiguous – the related noun is ambiguity - means ‘having more than one meaning, open to more than one interpretation, hard to understand, obscure’: it may apply, e.g., to a word or sentence, to an utterance, statement, or sign, or, more generally, to anything which could have a meaning and therefore be susceptible of interpretation. (The word comes from the Latin ambiguus, which means ‘going here and there, ambiguous’ and is formed from the verb ambigere, ‘to go round’, a compound from ambi- and agere, to lead or act.) For example, the ambiguous sentence ‘They told me when they left the house’ may convey information either about what they told me (‘when they left the house’ being understood as a noun-clause) or about when they told me (something else) (‘when they left the house’ being understood as an adverbial clause of time). Again, the ambiguous sentence ‘He doesn’t like failing students’ is open to at least three interpretations: if ‘failing’ is understood as a gerund, the sentence may mean either ‘He doesn’t like giving students such low marks that they fail’ or ‘He doesn’t like being unable to help students’; if ‘failing’ is understood as a participle or adjective, it means ‘He doesn’t like students who fail or are likely to fail’.
Sometimes ambiguity is unintentional - the speaker does not realise that what they have said may be interpreted in more than one way - but sometimes it is intentional – the speaker has deliberately chosen a form of words which they know is open to more than one interpretation, the intention being, e.g., to conceal what they really believe, or to protect themselves against accusations that what they have said has turned out not to be true. Politicians and oracles are, perhaps, particularly likely to make statements which they know to be ambiguous.
The Delphic Oracle, respected by the ancient Greeks for its unrivalled powers of prophecy, was renowned for the ambiguity of the replies it gave to those who consulted it. A famous instance concerns Pyrrhus (c319-272 BCE), king of Epirus, a region in the northwest of Greece, who intended to launch a campaign against the Romans. Consulting the oracle about the outcome of this course of action, he received a reply which is preserved in the Latin version of the Roman poet Ennius (c239-c169 BCE) (Annales 174):
Aio te, Aeacida, Romanos vincere posse.
This ambiguous sentence means either ‘Son of Aeacus, I say that you can conquer the Romans’ or ‘Son of Aeacus, I say that the Romans can conquer you.’ Pyrrhus, considering only the first alternative, embarked on his campaign, but when he was defeated, the oracle was able to claim that it was the second alternative that represented the true interpretation of its prophecy.