Alex Clark has made the following two comments (abstracted) in his comments to this post.
I find it quite frustrating that you challenge me to "pony up a story" but when pressed, you start saying the MP is just a conjecture and a program and not a theory.
So I read the Hauser et al paper where the only language specific bits are recursion and maps to the interfaces -- so where's the learning story that goes with that version of UG/FLN? Nobody gives me a straight answer. They change the subject or start waffling about 3rd factor principles.
I believe that these two questions betray a misunderstanding, one that Alex shares with many others concerning the objectives of the Minimalist Program (MP) and how they relate to those of earlier theory. We can address the issue by asking: how does going beyond explanatory adequacy relate to explanatory adequacy? Talk on the Rialto is that the former cancels the latter. Nothing could be further from the truth. MP does not cancel the problems that pre-MP theory aimed to address. Aspiring to go beyond explanatory adequacy does not amnesty a theory from explanatory adequacy. Let me explain.
Before continuing, however, let me state that what follows is not Chomsky exegesis. I am a partisan of Chomsky haruspication (well not him, but his writings), but right now my concern is not to scavenge around his literary entrails trying to find some obscure passage that might, when read standing on one’s head, confuse. I am presenting an understanding of MP that addresses the indicated question above. The two quoted paragraphs were addressed to (at?) me. So here is my answer. And yes, I have said this countless times before.
There are two puzzles, Plato’s Problem (PP) and Darwin’s Problem (DP). They are interesting because of the light they potentially shed on the structure of FL, FL being whatever it is that allows humans to be as linguistically facile as we are. The work in the last 60 years of generative grammar (GG) has revealed a lot about the structure of FL in that it has discovered a series of “effects” that characterize the properties of human Gs (I like to pretentiously refer to these as “laws of grammar” and will do so henceforth to irritate the congenitally irritated). Examples of the kinds of properties these Gs display/have include the following: Island effects, binding effects, ECP effects, obviation of Island effects under ellipsis, parasitic gap effects, Weak and Strong Crossover effects etc. (I provided about 30 of these effects/laws in the comments to the above mentioned post, Greg K, Avery and others added a few more). To repeat again and loudly: THESE EFFECTS ARE EMPIRICALLY VERY WELL GROUNDED AND I TAKE THEM TO BE ROUGHLY ACCURATE DESCRIPTIONS OF THE KIND OF REGULARITIES THAT Gs DISPLAY AND I ASSUME THAT THEY ARE MORE OR LESS EMPIRICALLY CORRECT. They define an empirical domain of inquiry. Those who don’t agree I consign to the first circle of scientific hell, the domicile of global warming skeptics, flat earthers and evo deniers. They are entitled to their views, but we are not required (in fact, it is a waste of time) to take their views seriously. So I won’t.
Ok, let’s assume that these facts have been established. What then? Well, we can ask what they can tell us about FL. IMO, they potentially tell us a lot. How so? Via the POS argument. You all know the drill: propose a theory that derives the laws, take a look at the details of the theory, see what it would take to acquire knowledge of this theory which explains the laws, see if the PLD provides sufficient relevant information to acquire this theory. If so, assume that the available data is causally responsible. If not assume that the structure of FL is causally responsible. Thus, knowledge of the effects is explained by either pointing to the available data that it is assumed the LAD tracks or by adverting to the structure of LAD’s FL. Note, it is critical to this argument to distinguish between PLD and LD as the LAD has potential use of the former while only the linguist has access to the latter. The child is definitely not a little linguist.
All of this is old hat, a hat that I’ve worn in public on this blog countless times before and so I will not preen before you so hatted again. What I will bother saying again is that this can tell us something about FL. The laws themselves can strongly suggest whether FL is causally responsible for this or that effect we find in Gs. They alone do not tell us what exactly about FL is responsible for this or that effect. In other words, they can tell us where to look, but they don’t tell us what lives there.
So, how does one go from the laws+POS to a conjecture/claim about the structure of FL? Well, one makes a particular proposal that were it correct would derive the effects. In other words, one proposes a hypothesis, just as one does in any other area of the sciences. P,V,T relate to one another via the gas laws. Why? Well maybe it’s because gases are made up of small atoms banging against the walls of the container etc. etc. etc. Swap gas laws for laws of grammar and atomic theory for innately structured FL and off we go.
So, what kinds of conjectures have people made? Well, here’s one: the principles of GB specify the innate structure of FL. Here’s why this is a hypothesis worth entertaining: Were this true then it would explain why it is that native speakers judge movement out of islands to be lousy and why they like reflexivization where they dislike pronominalization and vice versa. How does it explain these laws? As follows: if the principles of GB correctly characterize FL, then in virtue of this FL will yield Gs that obey the laws of grammar. So, again, were the hypothesis correct, it would explain why natural languages adhere to the generalizations GG has discovered over the last 60 years.
Now, you may not like this answer. That’s your prerogative. The right response is to then provide another answer that derives the attested effects. If you do, we can consider this answer and see how it compares with the one provided. Also, you might like the one provided and want to test it further. People (e.g. Crain, Lidz, Wexler, a.o.) have done just that by looking at real time acquisition in actual kids. At any rate, all of this seems perfectly coherent to me, and pretty much standard scientific practice. Look for laws, try to explain them.
Ok, as you’ve no doubt noticed, the story told assumes that what’s in FL are principles of GB. Doesn’t MP deny this? Yes and No. Yes, it denies that FL codes for exactly these principles as stated in GB. No, it assumes that some feature of FL exists from which the effects of these principles follow. In other words, MP assumes that PP is correct and that it sheds light on the structure of FL. It assumes that a successful POS argument implies that there is something about the structure of the LAD that explains the relevant effect. It even takes the GB description of the effects to be extensionally accurate. So how does it go beyond PP?
Well, MP assumes that what’s in FL does not have the linguistic specificity that GB answers to PP have. Why?
Well, MP argues that the more linguistically specific the contents of FL, the more difficult it will be to address DP. So, MP accepts that GB accurately derive the laws of grammar but assumes that the principles of GB themselves follow from yet more general principles many of which are domain general so as to be able to accommodate DP in addition to PP. That, at least, is the conjecture. The program is to make good on this hunch. So, MP assumes that the PP problem has been largely correctly described (viz. that the goal is to deduce the laws of grammar from the structure of FL) but that the fine structure of FL is not as linguistically specific as GB has assumed. In other words, that FL shares many of its operations and computational principles with those in other cognitive domains. Of course, it need not share all of them. There may be some linguistically specific features of FL, but not many. In fact, very very few. In fact, we hope, maybe (just maybe, cross my fingers) just ONE.
We all know the current favorite candidate: Merge. That’s Chomsky’s derby entry. And even this, Chomsky suggests may not be entirely proprietary to FL. I have another, Label. But really, for the purposes of this discussion, it doesn’t really matter what the right answer is (though, of course I am right and Chomsky is wrong!!).
So, how does MP go beyond explanatory adequacy? Well, it assumes the need to answer both PP and DP. In other words, it wants the properties of FL that answer PP to also be properties that can answer DP. This doesn’t reject PP. It doesn’t assume that the need to show how the facts/laws we have discovered over 60 years follow from FL has all of a sudden gone away. No. It accepts PP as real and as described and aims to find principles that do the job of explaining the laws that PP aims to explain but hopes to find principles/operations that are not so linguistic specific as to trouble DP.
Ok, how might we go about trying to realize this MP ambition (i.e. a theory that answers both PP and DP)? Here’s a thought: let’s see if we can derive the principles of GB from more domain general operations/principles. Why would this be a very good strategy? Well because, to repeat, we know that were the principles of GB innate features of FL then they would explain why the Gs we find obey the laws of grammar we have discovered (see note 6 for philo of science nostrums). So were we able to derive GB from more general principles then these more general principles would also generate Gs that obeyed the laws of grammar. Here I am assuming the following extravagant rule of inference: if AàB and BàC then AàC. Tricky, eh? So that’s the strategy. Derive GB principles from more domain general assumptions.
How well has MP done in realizing this strategy. Here we need to look not at the aims of the program, but at actual minimalist theories (MT). So how good are our current MT accounts in realizing MP objectives? The answer is necessarily complicated. Why? Because many minimalist theories are compatible with MP (and this relation between theory and program holds everywhere, not just in linguistics). So MP spawns many reasonable MTs. The name of the game if you like MP is to construct MTs that realize the goals of MP and see whether you can get them to derive the principles of GB (or the laws of grammar that GB describes). So, to repeat, how well have we done?
Different people will give different answers. Sadly, evaluations like these require judgment and reasonable people will differ here. I believe that given how hard the problems are, we have done not bad/pretty well for 20 years of work. I think that we have pretty good unifications of many parts of GB in terms of simpler operations and plausibly domain general computational principles. I have tried my own hand at this game (see here). Others have pursued this differently (e.g. Chomsky). But, and listen closely here, MP will have succeeded only if whatever MT it settles on addresses PP in the traditional way. As far as MP is concerned, all the stuff we thought was innate before is still innate, just not quite in the particular form envisaged. What is unchanged is the requirement to derive the laws of grammar (as roughly described by GB). The only open question for DP is whether this can be done using domain general operations/principles with (at most) a very small sprinkling of domain specific linguistic properties. In other words, the open question is whether these laws are derived directly from principles of GB or indirectly from them (think GB as axioms vs GB as theorems of FL).
I should add that no MT that I know of is just millimeters away from realizing this MP vision. This is not a big surprise, IMO. What is a surprise, at least to me, is that we’ve made serious progress towards a good MPish account. Still, there are lots of domain specific things we have not been able to banish from FL (ECP effects, all those pesky linguistic features (e.g. case), the universal base (and if Cinque is right, it’s a hell of a monster) and more). If we cannot get rid of them, then MP will only be partly realized. That’s ok, programs are, to repeat, not true or false, but fecund or not. MP has been very fertile and we (I?) have reason to be happy with the results so far, and hopeful that progress will continue (yes, I have a relentlessly sunny and optimistic disposition).
With this as prologue, let’s get back to Alex C. On this view, the learning story is more or less the one we had before. MP has changed little. The claim that the principles of GB are innate is one that MP can endorse (and does, given the POS arguments). The question is not whether this is so, but whether the principles themselves are innate or do they derive from other more general innate principles. MP bets on the second. However, MP does not eschew the conclusion that GB (or some equivalent formulation) correctly characterizes the innate structure of FL. The only question is how direct these principles are instantiated, as axioms or as theorems. Regardless of the answer, the PP project as envisioned since the mid 60s is unchanged and the earlier answers provided still quite viable (but see caveat in note 7).
In sum, we have laws of grammar and GB explanations of them that, via the POS, argue that FL has GBish structure. MP, by adding DP to the mix, suggests that the principles of GB are derived features of FL, not primitive. This, however, barely changes the earlier conclusions based on POS regarding PP. It certainly does not absolve anyone of having to explain the laws of grammar. It moreover implies that any theory that abstracts away from explaining these laws is a non-starter so-far as GG is concerned (Alex C provides a link to one such theory here).
Let me end: here’s the entrance fee for playing the GG game:
1. Acceptance that GG work over the last 60 years has identified significant laws of grammar.
2. Acceptance that a reasonable aim of research is to explain these laws of grammar. This entails developing theories (like GB) which would derive these laws were these theories true (PP).
3. More ambitiously, you can add DP to the mix by looking for theories using more domain general principles/operations from which the principles of GB (or something like them) follow as “theorems,” (adopting DP as another boundary condition on successful theory).
That’s the game. You can play or not. Note that they all start with (1) above. Denial that the laws of grammar exist puts you outside the domain of the serious. In other words, deny this and don’t expect to be taken seriously. Second, GG takes it to be a reasonable project to explain the laws of grammar and their relation to FL by developing theories like GB. Third, DP makes step 2 harder, but it does not change the requirement that any theory must address PP. Too many people, IMO, just can’t wrap their heads around this simple trio of goals. Of course, nobody has to play this game. But don’t be fooled by the skeptics into thinking that it is too ill defined to play. It’s not. People are successfully playing it. It’s just when these goals and ambitions are made clear many find that they have nothing to add and so want to convince you to stop playing. Don’t. It’s really fun. Ignore their nahnahbooboos.
 Note that this does not follow. There can be relevant data in the input and it may still be true that the etiology of the relevant knowledge traces to FL. However, as there is so much that fits POS reasoning, we can put these effects to the side for now
 One simple theory is that the laws themselves are innate. So, for example, one might think that the CNPC is innate. This is one way of reading Ross’s thesis. I personally doubt that this is right as the islands seem to more or less swing together, though there is some variation. So, I suspect that island effects themselves are not innate though their properties derive from structural properties of FL that are, something like what Subjacency theory provides.
 As many will no doubt jump our of their skins when they encounter this, let me be a tad careful. Saying that GB is innate does not specify how it is thus. Aspects noted two ways that that this could be true: GB restricts the set of admissible hypotheses or it weights the possible alternative grammars/rules by some evaluation measure (markedness). For current purposes, either or both are adequate. GB tended to emphasize the restrictive hypothesis space, Ross, for example, was closer to a theory of markedness.
 Observe: FL is not itself a theory of how the LAD acquires a G in real time. Rather it specifies, if descriptively adequate, which Gs are acquirable (relative to some PLD) and what properties these Gs will have. It is reasonable to suppose that what can be acquired will be part of any algorithm specifying how Gs get acquired, but they are not the same thing. Nonetheless, the sentence that this note is appended to is correct even in the absence of a detailed “learning theory.”
 None of the above or the following relies on it being GB that we use to explain the laws. I happen to find GB a pretty good theory. But if you want something else, fine. Just plug your favorite theory in everywhere I put in ‘GB’ and keep reading.
 Again this is standard scientific practice: Einstein’s laws derive Newton’s. Does this mean that Newton’s laws are not real? Yes and No. They are not fundamental, but they are accurate descriptions. Indeed, one indication that Einstein’s laws are correct is that they derive Newton’s as limit cases. So too with statistical mechanics and thermodynamics or quantum mechanics and classical mechanics. That’s the way it works. Earlier results (theory/laws) being the target of explanation/derivation of later more fundamental theory.
 The one thing it has changed is resurrect the idea that learning might not be parameter setting. As noted in various posts, FL internal parameters are a bit of a bother given MP aims. So, it is worth considering earlier approaches that were not cast in these terms, e.g. the approach in Berwick’s thesis.
 It’s oracular understanding of the acquisition problem simply abstracts away from PP, as Alex D noted. Thus, it is without interest for the problems discussed above.