The phrase “at loggerheads” basically means that two people or two parties cannot agree on something. The most common form of this phrase is stated like the following: “[they] are at loggerheads.” This idiomatic phrase in English is metaphorical, where a relationship is expressed through an analogy to physical items.
In physical terms, a loggerhead is an iron tool that is often used for heating liquid or manipulating various materials. Another definition for a physical loggerhead is a nautical term for a fixed part of a boat that can be used for tying ropes. A more metaphorical use for loggerhead is as a derogatory title for someone of low intelligence, similar to the term “blockhead.”
In its use as an idiom, the phrase “at loggerheads” generally expresses a visceral disagreement between two or more individuals or groups. One possible synonym for some uses of this phrase is “stalemate,” a chess term, where those who are “at loggerheads” may not be able to make progress on the negotiation of some issue. Parties who are “at loggerheads” may be involved in a long-term or short-term conflict precluding any agreement or negotiation.
Although this phrase is usually expressed with a plural, such as the pronoun “they” in the above example, some writers can use it along with a singular subject. For example, a headline that announces “the E.U. at loggerheads” is expressing a debate between multiple parties, while using the singular group title as the subject. Here, it is various elements of the E.U. or European Union who are disagreeing, but shortening the headline to the above forms helps to streamline the title without compromising its meaning, although some might suggest that this is a slightly improper, if not unusual, use of the idiom; theoretically, however, someone could even say that "he is at loggerheads with himself," in which an overtly singular subject is used to express an internal conflict.
The phrase “at loggerheads” is an example of an idiom that rests on a more antiquated original meaning. The loggerhead has ceased to be a commonly recognized tool for the majority of many English-speaking populations, outside of certain trade groups or types of workers. The idiomatic use has outlived the popular literal use in terms of common usage, but in looking at the contemporary evolution of the English language, even the idiom itself often seems outdated, replaced by more modern phrases, such as “gridlocked”. Writers or speakers might also say that “negotiations have come to a standstill,” or just use a more literal expression to replace the idiom, such as “unable to come to an agreement.”