Generally speaking, we refer to definitions when we wish to assign a particular, unique meaning or interpretation to a word. However, words appear in sentences and their meaning is conveyed in three ways: (1) by the definition, as given in one of the many dictionaries available to us; definitions usually vary from dictionary to dictionary; (2) by the specified context in which the target word appears; (3) by the general context when it is used, the inarticulated situation.

The difference between (2) and (3) is straightforward: take for example the word *animal*. If one is discussing animals in a zoo — a specific context — most creatures not on display in cages or enclosures are excluded. Here the term *animal* has a restricted meaning so that insects, vermin, fish would be excluded. If one refers to snakes in an aquarium it is safe to assume — but not certain — that talk is about water-snakes. A general context (3) refers to no specific habitat but a context is assumed, so that one could be talking about land or water snakes.

This blog contrasts two kinds of definitions: those which equate a term with its definiens, and those which propose areas of use.

A definition is not a description in the normal sense, but clarifies how a word — even a stream of related words — are used in everyday contexts. However, some dictionaries will also include definitions of terms which are not the ones currently circulating but add a note that this use of the word is archaic and rarely used. In doing so, the editor(s) acknowledge that uses change over time and, furthermore, that a word’s relationship to other words and the ideas these represent changes. It appears to be a very fluid situation: I propose to refer to this fluidity as “porousness” and therefore speak about porous definitions.

In special areas of interest — like Physics — some terms originate in ordinary language (*force* or *attraction*) whereas others were created to put a name to a discovered phenomenon. Contemporary physics has many examples, like *neutrino*, which Wikipedia states is, “A neutrino, a lepton, an elementary particle with half-integer spin, that interacts via only the weak subatomic force and gravity. The mass of the neutrino is tiny compared to other subatomic particles.”

This not the usual definition found in a dictionary but represents a mixture of a definition and a clarification. It is not at all porous, but firm as steel. There is nothing comparable in our — or any other — language: indeed, the definition for “neutrino” is valid for all languages! It is the prototype of a restricted definition. I cannot imagine how a restricted definition can be used in any other but its literal sense, where the definiens exhausts the meaning of the target word. Thus a sentences which contains the phrase “neutrino-like” would be an attempt only to expand the restricted definition — to break the bond — but it is difficult to see what this would mean, what feature of a neutrino as originally defined would be extracted and assigned to a different (new) phenomenon.

It is therefore useful to distinguish between terms which can — or are — given definitions that are meant to be used in specific cases only — which are deliberatively contrived and therefore have limited applications and are restricted- and definitions which are not steadfast in meaning but are what I describe as porous. Included would be words like *bridge*, which can refer to a structure built across a chasm, but which also means to step over two issues, may refer to the structure of a nose, refers to a reconciliation between two fractious parties and also is the name of a card-game which allows a partnership between two of four players.

Restricted definitions are widely used in technical fields and by scientists when they refer to their own domain of study. These groups develop an in-house set of terms and expressions which are often incomprehensible to outsiders. This barrier to understanding is not necessarily planned. People learn early that they operate in a multifaceted society where expressions are not only descriptive of a situation but often reflect the mood of a group. If one is not a member of such a group the discussion may pass without ruffling any feathers.

Words may have colour and get chosen to bias a scene. When this occurs, *generally used* is a reference to social customs which are — by definition — constricted to a group; it therefore is a social statistic.

This could be stated in terms of what people of a particular social group usually do with words and sentences in a given, specifiable, set of circumstances. A person who addresses others by “peace be with you” does not necessarily mean what he/she says: they may, in truth, be wishing you dead! In short, words do not necessarily mean what they say.

In live situations one puts two and two together: listens to the words, identifies them, observes how these are being used in a context, and uses other clues to interpret what the speaker really meant. If the other person is “flashing their eyes” and also reaches for their pistol, one is likely to accept the greeting “peace be with you” as displaying an aggressive, hostile greeting: one takes appropriate precautions.

Definitions as listed in a dictionary therefore need to be viewed with skepticism. The listed definition is a guide, not a legislative act. It indicates the possible use of a term, perhaps even a widespread use, but not necessarily the only, exclusive one.

There are many exceptions to this rule: specifically definitions of terms used in a particular branch of science, technology or in a professional sphere, like Canon or Criminal Law, which may be intended for use in an idiosyncratic limited manner and which occur by common agreement of those using it. Inevitably this use is meant to be exclusive, singular, and therefore is often incorrectly employed by outsiders but also by insiders who should know better!

Words, and expressions are produced by men, women and children in specific circumstances, most often willfully, with intent, not haphazardly. Few people adopt the view that a word must mean what they want it to mean. They follow custom (although poets have license to break customs) and when in doubt look up the word or expression in a reputable dictionary or Thesaurus.

There are exceptions primarily by those totally new to a language. Words, we say, have meaning. These are sounds which refer or point to events that may have nothing to do with the quality of sounds uttered. Thus words and a sentences constructed from words may be viewed as codes to inform others about states of affairs, and this may apply to the state of the individual or to impersonal, external, events.

We furthermore identify whether the information may be trivial, like “you have just stepped on a beetle,” or life-threatening like ”You have just stepped on a boa constrictor.” The expressions or sentences get part of their meaning from the circumstances under which these are uttered, although the circumstances are not part of the definition of the terms. Thus the meaning of a word depends on several circumstances so that a definition — as it appears in a reputable dictionary — should be viewed as a declaration about how the word could, or may be used; it is not prescriptive, only suggestive — and discretionary.

Finally, let me comment on the difference between (1) a restricted and porous definition and (2) the notion of a rigid designation, an idea we owe to the contemporary philosopher Saul Kripke (b. 1940) (see his Naming and Necessity, Harvard University, 1980). The idea of rigid designation has been discussed by several philosophers/logicians in discussions about “possible worlds”, not worlds as claimed to exist. The basic assumption generally made throughout history is that there is one real world and that we gain access to it by following strict procedural rules. This assumption found its most ardent expression in the work of Aristotle who argued that empirical research will reveal the “nature of things,” namely those features of something — an object or event — which were essential to it and those which are only added qualities.

So an object had two sets of features or qualities: those which were indigenous to it, its essences — which cannot be stripped from it without depriving its of its identity — and those that are ornamental,or contingent. As investigators we are therefore assigned two tasks: to identify the essence of each species of things and thereafter to classify to which broader category it belonged.

The Aristotelean approach and its method of searching for knowledge, although strongly and traditionally supported by Christian scholars, was forced into a compromise during the 16th century by technological discoveries which suggested that earlier procedures were not only capable of improving observational methods but could result in discoveries which were incompatible with the picture of the universe developed by previous generations. It could produce a “paradigm shifts” as described by T. Kuhn in the 1960s.

The most stunning example of this took place 30 years earlier with Einstein’s relativity theory, and before that when Darwin postulated that life forms on our planet had developed over several million years in an orderly manner according to some rules many of which had yet to be discovered. Structuralization was not a firm rule, as postulated by Aristotle, but was something which happened according to rules yet to be discovered, not a force acting upon nature but part of nature itself.

The end of the 19th century and the first half of the 20th century hammered home the idea we have to relinquish the old idea that *discovery* referred to unearthing treasures, like broken urns in the desert sand lying hidden somewhere below the surface, and to replace this with the notion that structure itself comes about, emerges and develops in a seemingly endless series, a process. And the orientation this discovery produced was the idea that there was not only one world, but that there are many, each being viewed as the best conjecture of a possible world. Thus a particular term could feature in several possible worlds, but in each case it involved a shift in its meaning.

There was, therefore, a place for rigid definitions of terms, provided these were confined to one possible world. Once defined such words could not transfer to another world without infringing its earlier rule of use.