The Logical Problem
Lecture 8
7 pillars of UG
1.
2.
3.
4.
5.
6.
7.
The Logical Problem
Centrality of recursion - LND
Language organ and modularity
Critical periods
Grammar gene
Sudden evolution of language
Speech is special
Logical Problem
7 Pillars of Emergentism
1. Learning on input (today’s talk)
2. Emergence of recursion (also today)
3. Modules are made not born (Rethinking)
4. L1-L2 competition (TICS article)
5. Polygenic emergent genome
6. Gradual evolution (MacWhinney 2004)
7. Speech relies on mammalian abilities
Logical Problem
Will they stand?
4
Logical Problem
Are packages monoliths?
• One pillar could crumble and the building would
not fall.
• But, the more the pillars the stronger the edifice.
• In practice, there are subgroups that subscribe
to different collections of pillars.
• Research must analyze one pillar at a time.
Logical Problem
Pillar #1: Chomsky (1980)
• The child’s acquisition of language is
“hopelessly underdetermined by the
fragmentary evidence available.”
• Degeneracy of input
• Lack of positive evidence
• Lack of negative evidence
Logical Problem
The Input is not Degenerate
• Newport, Gleitman, and Gleitman (1977)
showed that mothers speak grammatically
• Sagae, MacWhinney, and Lavie have
shown that the input in the CHILDES
database is as parsable as the Wall Street
Journal
Logical Problem
Two Arguments
• Argument from Poverty of Negative Evidence
(APNE)




Lack of correction
Rejection of correction
Gold’s proof
Recovery from overgeneralization
• Argument from Poverty of Positive Evidence
(APPE)
 Absence of input
 Weakness of learning mechanisms
 Degeneracy, incommensurability, …
Logical Problem
No need for positive evidence
• Chomsky 1980: “A person might go through much or all
of his life without ever having been exposed to relevant
evidence, but he will nevertheless unerringly employ the
structure-dependent generalization, on the first relevant
occasion.”
• Hornstein and Lightfoot 1987 “People attain knowledge
of the structure of their language for which no evidence
is available in the data to which they are exposed as
children.”
• Crain 1991 “...every child comes to know facts about the
language for which there is no decisive evidence from the
environment. In some cases, there appears to be no
evidence at all….”
Logical Problem
Motivating UG
• It is, for the present, impossible to formulate an
assumption about initial, innate structure rich enough to
account for the fact that grammatical knowledge is
attained on the basis of the evidence available to the
learner. Consequently, the empiricist effort to show how
the assumptions about a language acquisition device
can be reduced to a conceptual minimum is quite
misplaced. The real problem is that of developing a
hypothesis about initial structure that is sufficiently rich to
account for acquisition of language, yet not so rich as to
be inconsistent with the known diversity of language. - Chomsky 1965
10
Logical Problem
Power of APPE
• No need to discuss negative feedback
• Relies simply on facts about input corpus
• Constraints can be demonstrated
experimentally by providing sentences
that were “never heard”
Logical Problem
Structural Dependency
1. The man who is next in line is coming.
2. Is the man who _ next in line is coming?
3. Is the man who is next in line _ coming?
•
This only applies to non-parameterized
aspects of language, since parameter setting
requires positive evidence
Logical Problem
Graphically
• The boy who is smoking is crazy.
• Is the boy who smoking is crazy?
S
VP
NP
is
the boy
who is smoking
Logical Problem
crazy
13
Constraints
• The AUX of the relative clause must move from
INFL across the CP and COMP of the relative
clause (around “man”)
• But the Head Movement Constraint (HMC)
blocks this. Ross (1969)
• No such barriers exist in the main clause
• Also, movement of AUX would leave a gap that
violates the Empty Category Principle (ECP) in
the relative clause
Logical Problem
What counts as positive
evidence?
• Same AUX type
 Is the man who is next in line coming?
• Different AUX type
 Will the man who is next in line _ come?
• Item-based or class-based?
Logical Problem
The Input
• Pullum and Scholz (2002) found that 1%
of the Wall Street Journal (WSJ) corpus
has positive evidence. Most is of the
different AUX type. So there is a huge
amount of positive input. Or is there?
Logical Problem
Evidence from CHILDES
• A search of the English CHILDES
database (3 million utterances) by Lewis
and Elman (2001) found only one
utterance in the input to Adam.
• MacWhinney also found one in the input in
the Hall corpus.
Logical Problem
No evidence, no production
• So there is no positive evidence of this
type.
• But there is also no production, so how
can we know that children follow the
constraint.
Logical Problem
Experimental Evidence
• Crain and Nakayama (1987): Ask Jabba if the boy who
is watching Mickey is happy?
• Children (3-5) never moved the AUX of the relative,
although they did other strange things
• But the procedure gives the children the relative as a
frozen unit.


“the boy who is watching Mickey”
There is a fundamental pragmatic fact about relative clause
freezing that the structural analyses are ignoring, but …
• Still, let us grant that children have some sense of this
constraint by age 4. Is there really no input?
Logical Problem
Two other major sources
• Double AUX, Sub, WH
 Which is the dog that is clawing at the door?
 There are dozens of sentences of this type in the database.
 They show the relative clause staying intact.
 Elman and Lewis’s parser hates: the dog that clawing
• Single AUX, Sub, WH
 Where is the dog that you like?
 There are hundreds of these.
 They also illustrate keeping the subordinate clause frozen
Logical Problem
The biggest source
• You can learn from just main clauses
 Is the baby happy?
 Lightfoot (1986, 1997) degree-zero learnability
 Main clause movement is demonstrated.
 Sub clause movement is not illustrated.
 Conservatism: If something is not illustrated, it
is not legal.
21
Logical Problem
Item-based learning
• Item-based learning for AUX (will, is, can)
 Is the dog coming? is + (NP) + V
 Can you come?
can + (NP) + V
• Item-based learning for COP
 Is Billy your friend?
 Was he your friend?
Is + (NP) + PredN
Was + (NP) + PredN
• Eventual emergence of class-based patterns
 AUX + (NP) + V
 COPY + (NP) + NP
Logical Problem
Yes, it is Structural
• Movement formulated in terms of valency
relations (GRs), not position (crucial
assumption).
• Single AUX sentences teach the basic pattern.
• Double AUX sentences show that the choice
must be based on the AUX - V valency relation.
• For WH, the rule is WH - AUX - (NP) - V.
Logical Problem
Yes, it involves Recursion
• MacWhinney (1982, 1987) emphasizes
the fact that heads in valency relations
(item-based patterns) can themselves be
complex clusters.
• Word clusters implement recursion.
• Here, the whole relative clause is an NP
which is not a part of the AUX + (NP) + V
pattern that is learned.
Logical Problem
But, what is Recursion?
• Clustering produces embeddings and Xbar
• Psychological minimum is
 Head clustering (in a buffer or memory)
 Repeated application to clustered heads
 But, this probably operates in real time from
“left to right”
Logical Problem
Is Recursion Special?
• Do we cluster in space?
• Getting from Pittsburgh to ACL
• Climbing Stenhuten and reversing my path
• These use goal stacks and no words
• Working on an engine involves hierarchical
decomposition of parts without words
• Biederman’s geons constitute a hierarchical system
Logical Problem
Evidence for UG?
• The APPE fails -- there is positive
evidence.
• Learning is item-based and the structure
is emergent.
• So, yes, parsing depends on structure, but
not on UG
• So, this half of the pillar does not support
UG
Logical Problem
More on APPE - Kimball 1973
• Kids hear




It rains.
It may rain.
It may have rained.
It may be raining.
• But never
 It may have been raining.
• So, there is no positive evidence
Logical Problem
But a CHILDES search found
•
•
•
•
•
27 might have been
5 may have been
24 could have been
15 should have been
70 would have been
Logical Problem
So ...
• We can learn: modal + “have_been”
• There is really no shortage of positive evidence on this.
• Kimball’s mistake was to only search for “may have
been” since there were only 5 of these.
• Again, learning mechanisms have to be given a little bit
of power. We have to allow for extraction of IBPs and
then FBPs, along with clustering.
30
Logical Problem
Complex-NP Constraint
• Who did John believe __ kissed his
buddy?
• * Who did John believe the man that
kissed __ arrived
• * Who did pictures of ___ surprise you?
• * What did you see a happy ___ ?
• * What did you stand between the wall
and ___ ?
Logical Problem
Data from Seth (3-4)
•
•
•
•
•
•
•
What am I cooking on a hot __ ? (stove)
What are we gonna look for some __ ? (houses)
What is this a funny __ , Dad?
What are we gonna push number __ ? (9)
Where did you pin this on my __ ? (robe)
What are you shaking all the __ ? (batter and milk)
What is this medicine for my __ ? (cold)
Logical Problem
Is this error-free learning?
• There are definitely errors.
• There is definitely positive evidence.
• But it is true that errors seem to be
relatively scarce.
• So, this is “low error” learning.
• We will return to this later.
Logical Problem
Binding conditions
•
Devilliers, Roeper, and Vainikka 1990
1. When did the boy say he hurt himself?
2. When did the boy say how he hurt himself?
3. Who did the boy ask what to throw?
•
•
•
Young children can’t understand #3.
Children will associate “when” with “hurt” in #1
more than #2, but this understanding grows
with age
Therefore binding seems to be learned.
Logical Problem
Perhaps … But …
• Perhaps De Villiers et al. are saying that
what is UG is the ability to identify and
utilize the structure.
• Perhaps learning is just a matter of
identifying triggers (Sakas, Buttery)
• But the relevant structural details can be
expressed in terms of grammatical
relations and IBPs.
Logical Problem
APNE
• Failure of the APPE does not remove the
APNE.
• APNE provides evidence for a
“gyroscope” steering the child away from
the shoals of error.
• Thus, there could be evidence that
language is constrained by UG, even if
positive evidence is available.
Logical Problem
Correction is available
• Parents provide targeted correction for
identificable errors

Bohannon and Stanowicz, Nelson, Farrar, Cross
• Fine-tuning

Sokolov and Snow, Sokolov and MacWhinney
• Error feedback may be delayed

Brown and Hanlon
Logical Problem
But feedback is often ignored
• Child:
Nobody don’t like me.
• Mother:
No, say “Nobody likes me.”
• Child:
Nobody don’t like me.
• Mother:
No, say “Nobody likes me.”
• Child:
Nobody don’t like me.
• Mother:
No, say “Nobody likes me.”
• Child:
Nobody don’t like me.
•
[dialogue repeated five more times]
• Mother:
Now listen carefully, say “Nobody likes me.”
• Child:
Oh! Nobody don’t likeS me.
• (McNeill, 1966)
Logical Problem
Recovery from Overgeneralization
• u-shaped curve: went - goed - went
• child must stop saying:
 “goed”
 “unsqueeze”
 “deliver the library the book”
Logical Problem
An overly general grammar
correct grammar
overly general
grammar
Logical Problem
For example
went
jumped
goed
runned
falled
wented
Logical Problem
Feedback must be consistent
Feedback
No Feedback
Error
Hit
Miss
Correct
False alarm
Correct
rejection
High signal detection (d-prime) maximizes p(hit)/p(FA)
Hits close to 1.0 and FA close to 0.0
Logical Problem
But it is not
• Sometimes adults say “no” when a
sentence is correct
• Unless kids have extremely clear ability to
distinguish types of “no” they will be
confused
• So, direct reliance on provision of
corrective feedback may not be such a
great strategy
Logical Problem
Grammar may not matter
• Brown & Hanlon (1970):
• Adults understood 42% of the grammatical sentences.
• Adults understood 47% of the ungrammatical ones.
• Adults expressed approval after 45% of the
grammatical sentences.
• Adults expressed approval after 45% of the ungrammatical
sentences.
44
Logical Problem
So, let us grant
•
•
•
•
Corrective feedback is often not available.
If available, it is not consistent.
Even if consistent, it may be ignored.
But there are still five solutions to the
APNE form of the logical problem
Logical Problem
1. Conservatism
• Conservative child learners only use forms they
have heard adults use.
• Logically, the constraint of conservatism (Subset
Principle) would work, but overgeneralizations
prove that learners are not conservative.
• Item-based learning implements conservativism,
but it gives way to pattern-based learning
Logical Problem
Conservativism (cont.)
•
•
•
•
•
Who hit the little girl with the block today?
Who did the little girl hit _ with the block today?
Who did the boy play with _ behind his mother?
Who did the boy read a story about _ ?
Child never hears: Who do the boy read a story
that described _ ?
Logical Problem
Conservativism (cont.)
• *Who did John believe the man that
kissed ___ arrived?
• Who did John believe __ kissed his
buddy?
• *What did you stand between the wall and
__?
• *What did you see a happy ___?
Logical Problem
2. Indirect Negative Evidence
• Lasnik, Chomsky, Braine, Berwick, Siskind
average frequency of V
=
average frequency of V-ed
x
y
=
frequency of “go”
frequency of “goed”
x’
y’
• If x/y < x’/y’ by a large amount
• and if y is frequent, then y’ must be incorrect
Logical Problem
Indirect Negative Evidence (cont.)
•
do
tie
zip
squeeze
undo
untie
unzip
(unsqueeze)
Logical Problem
Indirect Negative Evidence (cont.)
• N in relative
• N extracted
=
N in complement
N extracted
• Bill thought the thieves were carrying the loot.
• What did Bill think the thieves were carrying.
• The police arrested the thieves who were carrying the
loot.
• * What did the police arrest the thieves who were
carrying?
Logical Problem
3. Probabilism
• Horning (1969) shows that Gold’s Proof fails for
probabilistic grammars.
• These can be identified on positive evidence alone.
• Labov’s variable rules are a good example of
probabilistic grammars.
Logical Problem
4. Competition
meaning
competition
word
word
episodic
support
analogic
pressure
Logical Problem
Competition - example
go + PAST
went
competition
episodic
support
go + ed
analogic
pressure
Logical Problem
Competition
• Other names for competition
 Blocking -- Baker 1970
 Uniqueness -- Pinker 1984
 Mutual exclusivity -- Markman 1986
 Semantic mapping -- Anderson 1978
• Competition includes conservatism,
probabilism, and indirect neg evidence
Logical Problem
Verb classes and
overgeneralization
•
•
•
•
Pour the water into the tub.
Fill the tub with water.
*Pour the tub with water.
*Fill the water into the tub.
Logical Problem
Donating the library the book
Dative Role
competition
to ___
“to”
episodic
support
verb
episodic
support
Logical Problem
V + NP + NP
extensional
pressure
57
Competition - complex
"pour arg1 arg2 arg3 "
competition
"1 pours 2 into 3"
lexical frame
"1 pours 3 with 2"
group frame:
1 verbs 2 into 3
group frame:
1 verbs 3 with 2
Logical Problem
Competition - semantic
demitassse
competition
episodic
support
cup
extensional
pressure
Logical Problem
Competition - definitions
• EPISODES are specific encounters with particular formfunction relations
• EXTENSIONAL PRESSURE is based on patterns
involving multiple exemplars.
• Morphological extension is to a new stem.
• Semantic extension is to a new referent
Logical Problem
Competition as the Oracle
• Competition provides negative evidence.
The child internalizes the adult who is now
the Oracle.
• This solves Gold’s Problem, since there is
now internal negative evidence.
Logical Problem
5. Recovery Mechanisms
• Cue Construction (why you can’t donate
the library the book)
• Monitoring (getting clearer episodic
encoding)
• Paying attention to negative evidence
Logical Problem
Conclusions
• The APPE is wrong, but there are low-error
constructions.
• The APNE is wrong, but some
overgeneralizations are hard to correct.
• Language learning is multiply buffered and
emergent.
• Pillar #1 is collapsing.
• Maybe it is time to look at CHILDES and not
(just) the WSJ
Logical Problem
URLs
• childes.psy.cmu.edu
• psyling.psy.cmu.edu
• talkbank.org
Logical Problem