Core Knowledge

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In the last lecture, we considered communication with language.

My overall plan now is to work backwards: the next item to consider is communicative action generally, and then its action generally.

I suggested that acquiring an ability to commmunicate with language typically involves (a) social interaction and (b) creating words.

I think looking at communication generally will help bring this into clearer focus.

But before I get into this, I want to take a huge detour.

The huge detour will allow me (i) to connect up the different things we've done; and (ii) pick up on some themes from your assessed essays.

(The detour means that this lecture, unlike the others, doesn't have a single unifying theme.)

I wanted to try to start drawing things together before the end of the last lecture.

This will mean a bit of repetition, but it will also help us in thinking through the issues together.

The Beginning of the End

This isn't a new question, but I think it's worth spending more time on it, partly because someone said in a seminar that we don't know what it is and partly because thinking about this is a way of organising much of what we've been learning.

What is core knowledge? What are core systems (≈ modules)?

The first, very minor thing is to realise that there are two closely related notions, core knowledge and core system.

The notion of a core system and that of a module are barely different; it's safe to treat these as interchangeable until you have a reason to distinguish them.

These are related this: roughly, core knowledge states are the states of core systems. More carefully:

For someone to have \textit{core knowledge of a particular principle or fact} is for her to have a core system where either the core system includes a representation of that principle or else the principle plays a special role in describing the core system.

So we can define core knowlegde in terms of core system.

The next step is to realise that there is a good reason why you don't know what core systems are.

Why don’t I know the answers?

Core systems are usually introduced implicitly, in explaining an idea.

\subsection{The idea}

‘We hypothesize that uniquely human cognitive achievements build on systems that humans share with other animals: core systems that evolved before the emergence of our species.

‘The internal functioning of these systems depends on principles and processes that are distinctly non-intuitive.

‘Nevertheless, human intuitions about space, number, morality and other abstract concepts emerge from the use of symbols, especially language, to combine productively the representations that core systems deliver’

Spelke and Lee 2012, pp. 2784-5

\citep[pp.\ 2784-5]{spelke:2012_core}.

So to properly understand what they are we would need (i) to have a deep understanding of the picture; (ii) and of the hypotheses it inspires; (iii) and of the evidence for these hypotheses, and then we would work back from this to say what core systems are.

Now you might say that this is terrible, how can scientists use terms without defining them.

But (a) it's not obvious that definitions are necessary for good science, or even that useful; and (b) compare the notion of knowledge: philosophers have made some informative observations about knowledge, but they've had no success at all in defining it.

(That said, I do think there's a particular problem with core knowledge.)

In answering the question, What is core knowledge? I think we should be inspired by the notion of radical interpretation.

‘All understanding of the speech of another involves radical interpretation’

Davidson 1973, p. 125

\citep[p.\ 125]{Davidson:1973jx}

(It's not just core knowledge; I think we have too approach science as radical interpreters ...)

How does radical interpretation work?

Interpretation is hard because there are two factors: truth and meaning.

The proposal Davidson makes is that we assume truth and infer meaning.

I'm recommending a similar strategy for core knowledge.

Very roughly, we take for granted that the evidence establishes various hypotheses. We then ask what core knowledge could be given these are true.

But more carefully, we first have to ask what motivates talk about core knowledge at all.

Fine, but this doesn't help us in practical terms. How are we to get a handle on the notion without doing lots of research?

The simple approach is to find out what people who use the term say it is.

But what is core knowledge?

What do people say core knowledge is?

\subsection{Two-part definition}

There are two parts to a good definition. The first is an analogy that helps us get a fix on what we is meant by 'system' generally. (The second part tells us which systems are core systems by listing their characteristic features.)

‘Just as humans are endowed with multiple, specialized perceptual systems, so we are endowed with multiple systems for representing and reasoning about entities of different kinds.’

\citep[p.\ 517]{Carey:1996hl}

(Carey and Spelke 1996: 517)

So talk of core knowledge is somehow supposed to latch onto the idea of a system.

What do these authors mean by talking about 'specialized perceptual systems'?

They talk about things like perceiving colour, depth or melodies.

Now, as we saw when talking about categorical perception of colour, we can think of the 'system' underlying categorical perception as largely separate from other cognitive systems--- we saw that they could be knocked out by verbal interference, for example.

So the idea is that core knowledge somehow involves a system that is separable from other cognitive mechanisms.

As Carey rather grandly puts it, understanding core knowledge will involve understanding something about 'the architecture of the mind'.

Illustration: edge detection.

‘core systems are

largely innate,
encapsulated, and
unchanging,
arising from phylogenetically old systems
built upon the output of innate perceptual analyzers’

\citep[p.\ 520]{Carey:1996hl}.

(Carey and Spelke 1996: 520)

\textit{Note} There are other, slightly different statements \citep[e.g.][]{carey:2009_origin}.

This is helpful for getting started.

But we quickly run into the problem that different researchers say different things, and it isn't obvious which differences matter.

We also run into the problem that the definitions on offer aren't obviously correct: they list features that maybe aren't all necessary.

core system vs module

Aside: compare the notion of a core system with the notion of a module

The two definitions are different, but the differences are subtle enough that we don't want both.

My recommendation: if you want a better definition of core system, adopt core system = module as a working assumption and then look to research on modularity because there's more of it.

An example contrasting Grice and Davidson on the wave.

\subsection{Compare modularity}

Modules are ‘the psychological systems whose operations present the world to thought’; they ‘constitute a natural kind’; and there is ‘a cluster of properties that they have in common’ \citep[p.\ 101]{Fodor:1983dg}.

These properties include:

\begin{itemize}

\item domain specificity (modules deal with ‘eccentric’ bodies of knowledge)

\item limited accessibility (representations in modules are not usually inferentially integrated with knowledge)

\item information encapsulation (modules are unaffected by general knowledge or representations in other modules)

\item innateness (roughly, the information and operations of a module not straightforwardly consequences of learning; but see \citet{Samuels:2004ho}).

\end{itemize}

‘core systems are

largely innate,
encapsulated, and
unchanging,
arising from phylogenetically old systems
built upon the output of innate perceptual analyzers’

(Carey and Spelke 1996: 520)

Modules are ‘the psychological systems whose operations present the world to thought’; they ‘constitute a natural kind’; and there is ‘a cluster of properties that they have in common’

innateness
information encapsulation
domain specificity
limited accessibility
...

So now we have a rough, starting fix on the notion we can ask a deeper question.

Why do we need a notion like core knowledge?

So why do we need a notion like core knowledge?

Think about these domains.

In each case, we're pushed towards postulating that infants know things, but also pushed against this.

Resolving the apparent contradiction is what core knowledge is for.

domain	evidence for knowledge in infancy	evidence against knowledge
colour	categories used in learning labels & functions	failure to use colour as a dimension in ‘same as’ judgements
physical objects	patterns of dishabituation and anticipatory looking	unreflected in planned action (may influence online control)
minds	reflected in anticipatory looking, communication, &c	not reflected in judgements about action, desire, ...
syntax	[to follow]	[to follow]
number	[to follow]	[to follow]

Key question: What features do we have to assign to core knowledge if it's to describe these discrepancies?

I think the fundamental feature is inaccessibility.

If this is what core knowledge is for, what features must core knowledge have?

limited accessibility to knowledge

To say that a system or module exhibits limited accessibility is to say that the representations in the system are not usually inferentially integrated with knowledge.

I think this is the key feature we need to assign to core knowledge in order to explain the apparent discrepancies in the findings about when knowledge emerges in development.

Limited accessbility is a familar feature of many cognitive systems.

When you grasp an object with a precision grip, it turns out that there is a very reliable pattern.

At a certain point in moving towards it your fingers will reach a maximum grip aperture which is normally a certain amount wider than the object to be grasped, and then start to close.

Now there's no physiological reason why grasping should work like this, rather than grip hand closing only once you contact the object.

Maximum grip aperture shows anticipation of the object: the mechanism responsible for guiding your action does so by representing various things including some features of the object.

But we ordinarily have no idea about this.

The discovery of how grasping is controlled depended on high speed photography.

This is an illustration of limited accessibility.

(This can also illustrate information encapsulation and domain specificity.)

maximum grip aperture

(source: Jeannerod 2009, figure 10.1)

This picture is significantly different from some competitors (but not Carey on number):

(1) because it shows we aren't done when we've explained the acquisition of core knowledge (contra e.g. Leslie, Baillargeon), and

(2) because it shows we can't hope to explain the acquisition of knowledge if we ignore core knowledge (contra e.g. Tomasello)

***todo*** say something about what we've learnt from each case.

Syntax is important because it pushes us away from the idea of 'systems that humans share with animals' \citep[p.\ 2784]{spelke:2012_core}

Or maybe identify themes and point out which cases they're

e.g. colour shows (i) that perceptual mechanisms are important and (ii) that infants' core knowledge persists into adulthood

domain	evidence for knowledge in infancy	evidence against knowledge
colour	categories used in learning labels & functions	failure to use colour as a dimension in ‘same as’ judgements
physical objects	patterns of dishabituation and anticipatory looking	unreflected in planned action (may influence online control)
minds	reflected in anticipatory looking, communication, &c	not reflected in judgements about action, desire, ...
syntax	[to follow]	[to follow]
number	[to follow]	[to follow]

Let me pause to evalaute the picture I offered in lecture 1 in the light of what we've learnt so far.

(I hesitate to do this because it shows the picture I offered you isn't very good.)

Take each case in turn.

For colour it works quite well, providing, as I suggested last week, that acquiring words is a creative process of social interaction.

What about physical objects? Here there's no indication that using labels for objects drives a developmental change, and it's hard to see why it would.

(It's more plausible that tool use rather than word use matters; but even this is is hugely speculative.)

So no marks for that case at all.

What about minds, and in particular beliefs?

Superficially things look better here. There is both evidence that rich forms of social interaction facilitate development \citep{Hughes:2006fu}

and also evidence that language matters in various ways \citep{Astington2005ot}.

But these probably don't connect in the simple way I envisage.

Social interaction might matter because it provides experiences of perspective differences, or because it motivates children to think about others' minds.

And language might matter because having sentences around enables them to keep track of beliefs, or because using relative clauses might clue them in to a relation between beliefs and what utterances of sentences express.

So here the picture isn't right, but it might not be a million miles off either ...

It's wrong to think that labelling beliefs matters; but it may be that being able to talk about beliefs (implicitly or otherwise) does matter for coming to have knowledge of them.

So far we've ignored what is usually regarded as a paradigm case for core knowledge ...

next: syntax