Poverty of The Stimulus and the Rationalist/Empiricist Debate

(Note: This is my second post in the series about the philosophy of cognitive science)

Imagine that you’re a traveler passing through a small village in a foreign land, and as you’re trying to communicate (with difficulty) with the locals, you see a rabbit running by you. As it runs by, a local says, “Gavagai!” Now, of course, you might infer that he was referring to the rabbit. So does “gavagai” mean rabbit? Could it mean furry? It could even mean Nice Day! You don’t know.

This dilemma was devised by Van Gordon Quine (1960) to refer to something called the “poverty of the stimulus” problem – under-determination. If we consider the brain to be a sort of information-processing device, an instantiation of the abstract concept of a “mind,” then researchers are dogged by the issue of language-learning, and all kinds of inductive learning in general. Noam Chomsky, renowned linguist and cognitive scientist, framed the problem thus – children can learn a grammar which can produce an infinite number of sentences by only hearing a finite number. How do children possess the universal and consistent ability to learn languages, using a relatively small amount of data to learn an internal representation of language capable of making sense of unfamiliar languages?

Chomsky believes that certain aspects of language must be innate. According to him, certain (universal) aspects of language are encoded into our genome. Important as this question is, it in turn raises bigger ones – to what extent is our knowledge and mind predetermined?

As Dwight Schrute from The Office might say, there are basically two schools of thought. The first is rationalism, the philosophy based on the belief that our mind comes equipped with innate ideas. The  second is empiricism, which believes our mind is fully shaped by experience.

Empiricism, influenced greatly by the thinker John Locke, promotes the idea of a tabula rasa, or blank slate – at birth, we are all equal, and our minds are fully shaped by the experiences and actions of our lifetimes. It’s an attractive idea, and one of the tenets of libertarianism, the political philosophy of which Locke was in many ways an intellectual ancestor. With empiricism, the entirety of knowledge is based in ideas. Some ideas are direct, others are abstract and indirect. Mathematical concepts, such as the triangle, would be considered “abstract.” Although some would argue that triangles, as well as other abstract concepts, might be impossible to properly represent in an idea-scheme, some empiricists such as John Stuart Mill went so far as to proclaim that all of mathematics COULD be depicted in terms of definitional relations between ideas. The purpose of reason and logic, then, were to organize ideas. One important empiricist belief is that the mind is a domain-general device, in that it uniformly picks up and learns from experiences and stimuli.

Rationalism is quite the opposite – according to this philosophy, the mind comes equipped with innate ideas. Essentially, the mind takes an axiomatic approach about learning about the world, with the axioms built in. Some knowledge is not derived from experience. This is because many ideas, such as identity, must be inherent, or otherwise we wouldn’t have any ideas at all. This is where Descartes’ “cogito ergo sum” comes in. This is also where Descartes’ dubious proofs of the existence of God come in – as I mentioned in a previous post, he believed that since we had an idea of God, it had to be implanted in us innately. And what force could possibly provide an idea of the existence of God? Why, God him and or herself. Also, the rationalists believe that the mind is a domain-specific device – because of innate characteristics, it is specially structured to learn from different stimuli differently.

So which is it, empiricism or rationalism? This is, at a base level, the philosophical equivalent of nature vs. nurture, and in many ways, not very practically applicable, because it doesn’t tell us much anything useful. The ideas of the innateness of language and the modularity of the mind (we use different parts of our brain to respond to different situations, eg. we’re really smart if we suspect someone might be cheating) are scientific, not philosophical theories. The rationalism/empiricism debate is an important episode in the history of the philosophy of the mind, but it went back to a time when thinkers didn’t make a connection between the actual physical structure of the brain and the structure of the “mind.” Now, from a scientific perspective, we cannot proclaim rather little, because nature vs. nurture is an ongoing debate with far-reaching societal, and even political, considerations (think libertarianism). Some scientific theories, such as the poverty of the stimulus problem, argue for a certain representation of the mind, but whether or not there are significant preexisting structures in inexperienced minds that produce variation or bias in learning abilities and predispositions is still an open question.

Stay tuned for my next post, on the problem of other minds and first- and third-person perspectives!



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