Of course things aren't that simple. Chapter two outlines some of the theoretical debates over the nature of pidgins, creoles, and the processes (such as nativization and stabilisation) that change them. Holm begins historically, tracing the early history of European pidgins and creoles (touching on Lingua Franca and maritime jargon) and the work of Van Name and Schuchardt in the second half of the nineteenth century. He switches to a more thematic presentation for the modern debates. One of these is between universalists, who argue that all creoles share common features resulting from human language universals (in domains such as adult language learning) and substratists, who stress the influence of substrate languages. Others centre on the "creole continuum", the social continuum of dialects produced when creoles in prolonged contact with their superstrates "decreolize", and the amorphous boundaries between creoles and post- and semi-creoles. And one controversial idea is monogenesis, that all creoles (or all Atlantic creoles) derive from a single source, a Portuguese-based pidgin.
Holm describes his own position as "moderate substratist".
"[W]hile universal tendencies in adult second-language acquisition carried over into pidiginization and creolization play a role in shaping creole languages... a significant number of the features in a creole language that are not attributable to its superstrate can be traced to parallel features in its substrate languages. Together with creole-internal innovations, borrowing from adstrate languages (those which are neither superstrate nor substrate) and the convergence of all or some of the above, these account for the features that distinguish creoles from their lexical source languages."An Introduction to Pidgins and Creoles is, however, a survey of creoles with some suggestions as to theoretical implications, not an argument for a particular theoretical position.
Chapter three is a sociolinguistic survey of the world's creoles, with a brief introduction to a group of languages followed by a more detailed look at one example. The seven covered are the Portuguese-based creoles (example Angolar Creole Portuguese), Spanish-based creoles (Papiamentu Creole Spanish), the Dutch-based creoles (Negerhollands Creole Dutch), the French-based creoles (Haitian Creole French), the English-based Atlantic creoles (Jamaican Creole English), the English-based Pacific pidgins and creoles (Tok Pisin), and pidgins and creoles based on other languages (Nubi Creole Arabic). Overall it is clear that "sociolinguistic factors are essential parts of the definition of both pidgins and creoles".
The remaining chapters are more technical, but even here Holm glosses technical terms as he goes, making it easier for non-specialists. When the comparative phonology in chapter five comes to apicals, for example, the discussion begins "Apical consonants are produced with the tip of the tongue against the upper teeth or the alveolar ridge; they can be a stop (e.g. [d]), a nasal [n], a lateral [l] or a flap [r]. These sounds are related in a number of African languages ...". Creole phonology exhibits some universal tendencies, but also clear evidence of substrate influence, of a 'double identity': "the balance of European versus non-European features varies considerably from creole to creole, all varieties - even post-creoles and semi-creoles - share this double identity to some degree".
Chapter four covers lexicosemantics, looking at the kinds of words retained and the kinds of changes they undergo. While most creole lexical terms come from the superstrate language, they are often derived from archaic and dialect or regional forms. Substrate influence shows itself in some direct borrowing or retention, but more widely in patterns of morphological and semantic changes to superstrate lexical items. Creole lexicosemantics is a powerful tool for social history, providing evidence for patterns in immigration and slave-taking — highlighting, for example, the general importance of Portuguese in the Atlantic slave trade.
Chapter six is a comparison, across the seven creoles described in chapter three, of various syntactical features: tense, aspect and other verbal markers; forms of "be"; serial verbs; noun phrase features; function words; and word order. Nubi Creole Arabic and Tok Pisin form a kind of "outgroup", with Atlantic creoles "a typological group of languages sui generis". From this survey Holm finds
"a strong case for parallel independent development ... It is hardly controversial to observe that the Atlantic creoles arose among speakers of partially similar African languages learning partially similar European languages under partially similar social conditions."But he finds "no linguistic data that could be interpreted as unambiguous evidence of neurally based universals".