In my (2011) paper on the indeterminacy of word segmentation, I despaired of the task of distinguishing between “words” and “affixes”, but in the meantime, I have become more optimistic. I am now ready to answer the above question (“What is an affix?”) by a proposal for a definition.
It should be noted that in general, when a linguist asks “What is an X?” (where X is a general concept), this means (or should mean) “what is the best general definition of the term X?”. This is because the notion of X cannot be presupposed to exist in the world, and all we know is that there is a well-known term that we want to continue to use and whose definition is unclear.
In 2011, I was resigned to giving up the terms “word” and “affix” (and in 2015, the term “clitic”), but of course, linguists continue to use these terms. So I kept wondering whether one can find a rigorous definition that corresponds to at least 80% of their usage. This matters, because many general claims depend on the notion of affix, and we want to be able to test such claims and develop them further. Two striking examples are the claim that there is a suffixing preference (e.g. Himmelmann 2014, also discussed here) and that “grammatical complexity” is correlated with social factors (Lupyan & Dale 2010).
A year ago, I started working on a review of the “Oxford Handbook of Polysynthesis” (published as Haspelmath 2018a), and while the concept of “poly-synthesis” was poorly defined in the volume, I wondered again whether at least the simpler concept of “synthesis” could be given a clear definition. The latter seems even more important, also because there are many claims about regaular developments from synthetic to analytic and back again (dubbed the “anasynthetic cycle” in my 2018b paper).
My current answer (contrasting with my agnostic attitude in 2011) is yes – the term affix can be defined as follows:
Affix: An affix is a non-promiscuous bound form which is not a root.
It is not possible to characterize affixes semantically, but roots can be defined as “morphs that denote things, actions or properties” (Haspelmath 2012), and by saying that affixes are non-roots, we come fairly close to capturing what they can do semantically (basically, everything else). One may object that some affixes denote people (= a subtype of thing), and some denote actions (e.g. causative affixes), and diminutive affixes may denote the property ‘small’ – but I said earlier that we should be content with 80% overlap with traditional usage.
An affix is also characterized as a bound form, because free forms (= forms that can occur in isolation) would never be considered affixes. Upon first hearing hi Dad!, the analyst might suspect that hi- is a vocative prefix, but once it is recognized that hi! can occur on its own, such a description becomes impossible.
Now crucially, an affix differs from a clitic in that it is non-promiscuous, meaning that it always occurs on roots of the same root-class – either always on noun roots, or always on verb roots, or always on adjective roots (these are the three root-classes, by definition). It is true that traditionally, the term “clitic” is thought of as being somehow phonologically special (needing a host to “lean on” to be pronounced), but linguists have not been able to give a general phonological characterization of this notion (as is made quite clear in the concluding chapter of Spencer & Luís 2012). Traditionally, affixes have often been characterized as somehow phonologically “more attached” than clitics (Zwicky & Pullum 1983), but nobody has been able to give clear criteria for this that can be applied to all languages. (There is a widespread feeling that languages have “phonological words”, but if these are identified differently in different languages, there is no rigorous way of testing such claims.)
The traditional use of the term “affix” is heavily influenced by linguists’ experience with Indo-European (and Semitic) languages, and in these languages, elements such as tense-aspect markers, plural markers and comparative markers are generally restricted to verbs, nouns, and adjectives respectively – and I think that this is what makes us call them affixes. If a bound aspect marker is not restricted to occurring on verbs (like the Mandarin perfective marker le, which may occur after the verb, or after the object, etc.), it will not be called an affix. Likewise, if an object person index always occurs on the verb (as in Arabic and Hebrew, e.g. עֲזַבְתָּ֑נִי ʕazab-ta-ni [forsake-2SG.SBJ-1SG.OBJ] ‘you have forsaken me’), then it is regarded as an object person suffix. By contrast, Portuguese object person indexes sometimes occur on the verb (vejo-a ‘I see her’) and sometimes on an element preceding the verb (que=a vejo), so they are promiscuous, and hence they are clitics.
This also gives the right results for articles (“right” in the sense that they tend to agree with what people have always said). The English article a(n) has two different phonological shapes (a and an) depending on the context, so by a phonological characterization, it looks more like an affix. But it need not occur on a noun (as in an apple) – it may also occur on an element preceding the noun which is not a noun (a green apple). By contrast, the Swedish definite article -en (e.g. kung-en ‘the king’) always occurs on a noun, and is thus regarded (and written) as a suffix. Bound prepositions in European languages may occur directly on the noun (French à pied ‘on foot’), but they may also occur on other pre-nominal elements, and thus they are not prefixes. By contrast, Egyptian Arabic prepositions always occur on nouns – because there are no prenominal modifiers – and may thus be regarded as prefixes (but in Standard Arabic, demonstratives precede the noun, so that the prepositions are not always adjacent to the noun).
I should add that the definition involves a notion of “occurrence of a bound form on another element” (its host) that I have not characterized clearly yet. A bound form cannot occur on its own, and in most cases, it is immediately clear what the host of a bound form is. The host of the English Genitive clitic ’s is the immediately preceding element (a noun or some other element in a postnominal modifier), and the host of the Portuguese clitic =a is the verb or some preverbal element. However, some bound forms do not have a very clear host. German has a set of discourse particles (e.g. wohl, ja, doch) that cannot occur on their own and cannot occur clause-initially, but it is not clear that their host is either the element preceding them or the element following them (e.g. sie hat es ja gesehen [she has it PCL seen] ‘she saw it (as you know)’ – here it is unclear whether the particle ja “occurs on” es or on gesehen – it seems that it simply needs to be in a particular clause-medial position). However, it is not actually crucial for the definition of affix that we identify the host of any bound form – since affixes always occur on roots of the same class, there is never any question which is their host.
So it seems that the new definition of affix (as a non-promiscuous bound form which is not a root) works quite well, and I again acknowledge the contribution of Harald Hammarström in leading my thinking in this direction. But how happy are we with such a definition? Is there anything deep about affixes?
Of course not – but that was not the point. I still do not think that such a definition gives a justification for a deep division between a morphological and a syntactic component, and the definition does not get us any closer to understanding why languages have the kinds of forms and rules that they have. All it could do is give us a better understanding of what a colleague means when she talks about “affixes”, assuming that linguists use the term in the same way. It is thus a contribution to a possible terminological standardization – not more than this, but also not less (because without standard terminology such as the IPA, we will keep talking past each other even at the lower levels).