Phonological traces of syntactic phases: PIC à la carte?

Why phonology is flat: the role of concatenation and linearity Linguistic structure is hierarchical. But how are hierarchical relations expressed? Is there just one way of implementing hierarchy, or are there different formal expressions that are not just notational variants? Trees (or equivalent graphic representations such as brackets) are the regular and intuitive way of expressing hierarchical relations: they are the default in all areas, i.e. syntax, morphology, phonology, semantics etc. The phonological literature knows a different means of encoding hierarchical relations, though: lateral relations (government and licensing). These are the genuine contribution of Government Phonology to the field. Lateral relations are representationally and formally distinct from trees: although they establish a hierarchical relation between two items of which one is the head of the construction (as do trees), the items engaged are not necessarily adjacent, and they are not grouped into higher units in any way. Also, importantly, two items that contract a lateral relation cannot be as a whole engaged in another lateral relation: lateral relations are not recursive. This is the description of lateral relations in strict CV (Lowenstamm 1996). It is true that they could be recursive in Standard Government Phonology where the rhyme governs its onset, but may also dominate a branching nucleus that constitutes a governing domain in its own right. Also, a governing relation typically groups items into packages in Standard GP: for example, this is the case for the head-complement relation among vocalic items, which describe a branching nucleus. Standard GP was thus hybrid: it made cohabitate both types of hierarchical structure in the same representation. Tree structure, however, was already depleted and some structure and causality was expressed by lateral relations. It was noticed early on by Takahashi (1993) that this hybridism is redundant and runs the theory into irresolvable trouble. As a consequence, either the lateralisation of structure and causality is taken all down the road, or trees prevail and lateral relations are a bad idea after all. Strict CV follows the former option: it completes the lateral programme such that there are no trees left in phonology (in the area of syllable structure or elsewhere, Scheer 2004: §165, 2012). That is, deforestation shifts the functional burden from trees to lateral relations, and does that 100%. The purpose of this talk is to show that the absence of trees from phonology and hence the existence of an alternative means of expressing hierarchical relations follow from two things: a design property of syntax, concatenation (which is absent from phonology: phonological computation does not concatenate anything), and an input condition to phonological computation, linearity (which is absent from syntax: in minimalism linearity is introduced post-syntactically). In (morpho-)syntax, trees are a consequence of concatenation, and of nothing else: this is the essence of the universal hierarchyand tree-creating mechanism Merge (even though concatenation and labelling/projection may be distinct operations). It thus follows from the fact that phonology does not concatenate anything that there cannot be any tree-building device in this module: no concatenation, no trees. An appreciable side-effect of this perspective is the explanation of a long-standing observation, i.e. the absence of recursion in phonology: no trees, no recursion. On the phonological side, I argue that linearity produces lateral relations, and by the same token makes trees unworkable. That is, concatenation and hence trees could not exist in an environment where items are arranged along a predetermined linear order. In the absence of the arboreal option, phonology thus needs to find an alternative means of expressing hierarchical relations, one compatible with linearity. Lateral relations serve this purpose: they are a creature of linearity (and hence unworkable in morpho-syntax). The perspective described is based on two real-world properties that any implementation of human language (the one we know or other logically possible systems) is confronted to and will