Here’s just some thoughts I’ve been mulling over on representing segment length. I’d love to get feedback. I’m a bit rusty since I haven’t really thought hard about phonology for a couple of years.
It seems that representational theories of segment length (two-root theory or moraic theory) are pretty good at addressing some basic properties of long segments. For example, in some cases length is preserved (compensatory lengthening) when the segment degeminates. That fact makes sense if the length is represented as double linking to a timing slot and degemination is simply unlinking to the extra slot, leaving it free to relink somewhere more hospitable.
But, an interesting issue with both two-root theory and moraic theory is that length really seems to be a binary distinction. A segment is either long or short and that’s that. But the representational theories don’t really capture this. And they don’t provide any reasons why there isn’t three-way or four-way contrasts in segment length (or more). This is pretty obvious in the two-root theory since there really is no reason not to have a single segment linked to more than two timing units. I think it’s also a problem in the moraic theory since vowels at least allow linking to multiple morae. And there is no explicit reason why consonants can’t be doubly linked. At best there seems to be a general rule against having more than one long segment in a syllable (except maybe word-finally).
Maybe this isn’t such a big problem for moraic theory. In fact, if there is a very general syllable markedness constraint (or set of constraints) that cap things off at 3 moras per syllable, then you’ve subsumed this to general principles and not just a stipulation about [±long].
But then, how do you enforce these restrictions in OT? Inviolable output constraints? Restrictions on GEN? Isn’t that just trading stipulations up? For some reason I can’t help but feel a little let down by these representational theories.