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The Computational Theory of Mind (2015)

plato.stanford.edu

31–40 of 95 posts

Re: The Computational Theory of Mind (2015)

#31

It seems like basic materialism to claim that the brain could be simulated by a large enough Turing machine. But that claim would not necessarily imply that a Turing machine is a useful model for brain. A Turing machine isn't necessarily even used as the working model of a computer though it conceivably could be. Edit: My comment is basically asking what saying "the mind is a Turing machine" really means. It seems li…

Are you absolutely convinced that you can build a sentient mind out of clockwork parts? Because that's what your interpretation of basic materialism implies.

In principle? No question.

In practice? No chance.

Re: The Computational Theory of Mind (2015)

#32
post #22

Earlier quoted context omitted.

The definition of "a conscious experience" is so vague and circular that I'm not sure the question of "whether an X can have conscious experience" (where X is computer, dog, fish, human infant...) is even all that meaningful. Either way we certainly don't have any indication that it is impossible in principle for a Turing machine to perform the same kind of calculation that gives rise to conscious experience in human…

> I'm not sure the question of "whether an X can have conscious experience" (where X is computer, dog, fish, human infant...) is even all that meaningful. I do know that I have a conscious experience, so that's quite meaningful - to me. I cannot check that any other being has similar feelings, so the doubtful question would be whether "an X other than me can have conscious experience"; but people with good manners ma…

Why is it polite to assume non concious entities are conscious?

Re: The Computational Theory of Mind (2015)

#33

Earlier quoted context omitted.

Are you absolutely convinced that you can build a sentient mind out of clockwork parts? Because that's what your interpretation of basic materialism implies.

In principle? No question. In practice? No chance.

How would a clockwork model of the mind explain the phenomenon of consciousness (as opposed to computation)?

Re: The Computational Theory of Mind (2015)

#34
post #33

Earlier quoted context omitted.

In principle? No question. In practice? No chance.

How would a clockwork model of the mind explain the phenomenon of consciousness (as opposed to computation)?

The idea is that consciousness is what a planning algorithm feels like from the inside. A planning algorithm requires representations of the entities relevant to planning, e.g. various objects in the world, relevant laws, internal states such as emotions, motivations, etc. It is these representations from an internal perspective that have something it is like to have them. But the fact that this planning algorithm is constructed out of mechanical components is irrelevant.

Computation is just an abstract description of the behavior of some classes of systems. But it doesn't exhaust the set of possible descriptions for a system. Some subset of computational systems might also have a description in terms of consciousness.

Re: The Computational Theory of Mind (2015)

#35
post #23
post #18

Earlier quoted context omitted.

Simple: Find something that the brain does that could not, in principle, be emulated by a Turing machine or equivalent. So far we don't know of any such thing (since quantum mechanics is computable and everything including the brain is ultimately quantum mechanics).

If there is nothing that is uncomputable, then doesn't that mean the hypothesis is unfalsifiable?

It's worth noting that the theory that a falsifiable hypothesis constitutes scientific investigation (as proposed by Popper) isn't really the gold standard of the philosophy of science any more - especially since Popper's formulation is known to be pretty shoddy.

Re: The Computational Theory of Mind (2015)

#36
post #18
post #17

How can such a theory be falsified?

Simple: Find something that the brain does that could not, in principle, be emulated by a Turing machine or equivalent. So far we don't know of any such thing (since quantum mechanics is computable and everything including the brain is ultimately quantum mechanics).

True random number generation can't be done by a deterministic computer, and it appears that human brains can, although not conclusive yet, and the precise mechanism is unclear:

- https://www.ncbi.nlm.nih.gov/pubmed/15922090

Re: The Computational Theory of Mind (2015)

#37

In a different lifetime I got to take a few classes with Jerry Fodor, and although this publication references him extensively, one of his most succinct arguments for the computational theory of mind is only alluded to: the lack of alternatives. Fodor was a snappy writer and talker. I urge you to view his videos if they can be found on YouTube. Unfortunately he passed away recently. The argument goes something like t…

The problem with that argument is that it "the computational theory of mind" isn't a "theory of mind" -- so I don't think we have any.

A TOM needs to explain "mental life", at best the CTOM provides a model of a very narrow sort of cognition (inference over propositions).

There's a gigantic (and in my view, deeply implausible) leap from "hey this kinda works for modelling inference in animals" to "hey this is how The Mind! works".

Not only do all CTOM models fail for actual inference in animals where we can be reasonably sure inference is taking place (due to the frame problem), it clearly fails for non-inferential processes and states (eg., emotions/environmental-action/...).

These non-inferential processes are regarded by CTOMists as "black boxes" that just "plug into" the "Real Mind" (ie., inference over propositions).

I dont think Fodor's argument holds here: it is tantamount to saying, "hey we've explained light with waves, why dont we just explain everything with waves!" -- the cost to that approach should be obvious.

The problem this field has is that its being lead by computer scientists not neurobiologists. You ask a computer scientist what the right model of anything is, and they'd reply with a logic.

We do not, however, model causal reality with logic. Temperature isnt computed from a 'logic of molecule motion', it is done via a causal model which relates causal variables to one another.

Re: The Computational Theory of Mind (2015)

#38
>> The first argument emphasizes learning (Bechtel and Abrahamsen 2002: 51). A vast range of cognitive phenomena involve learning from experience. Many connectionist models are explicitly designed to model learning, through backpropagation or some other algorithm that modifies the weights between nodes. By contrast, connectionists often complain that there are no good classical models of learning [4.2 Arguments for connectionism].

There is no special need for a specific model of "learning" in a classical setting. Given an inference procedure, such as induction, adbuction or deduction, that can derive new facts and rules in a logical language from observations and a pre-existing theory (i.e. a pre-existing set of facts and rules), all it takes to "learn" is to store the newly derived facts and rules to a database.

I mean "learning" in the sense of Mitchell's definition of _machine_ learning, as (informally) the ability of a system to improve its performance from experience. In this sense, a system that starts with a database of logical facts and rules and adds new facts and rules derived from new observations is "learning".

You can find many examples of learning in a classical, logic setting in the early ('70s and '80s) machine learning literature, particularly with propositional logic learners such as decision list and decision tree learners, the most famous of which are J. Ross Quinlan's ID3 and C4.5 decision tree learners. The field of Inductive Logic Programming studies learning in First-Order Logic languages, especially logic programming languages such as Prolog and Answer Set Programming, and includes early systems such as Shapiro's Model Inference System, Quinlan's FOIL (First-Order Inductive Learner, essentialy a relational version of ID3), Muggleton's Progol and Srinivasan's Aleph (based on inverse entailment), and more recently ASP learners such as ASPAL (Mark Law), or Statistical Relational Learning techniques, e.g. by De Raedt, Kerstig, Getoor, Taschar and others; etc etc.

Bottom line- there is a huge body of work on learning in a classical, logic setting. There is no serious objection that "there _are_ good classical models of learning". Such models are all over the place in machine learning. In fact, they tend to be the most carefully characterised models of machine learning.

Re: The Computational Theory of Mind (2015)

#39
>> However, the mechanisms that connectionists usually propose for implementing memory are not plausible. Existing proposals are mainly variants upon a single idea: a recurrent neural network that allows reverberating activity to travel around a loop (Elman 1990). There are many reasons why the reverberatory loop model is hopeless as a theory of long-term memory. For example, noise in the nervous system ensures that signals would rapidly degrade in a few minutes. Implementationist connectionists have thus far offered no plausible model of read/write memory. [4.3 Systematicity and Productivity]

I wonder: is this information outdated?

A Neural Turing Machine (first described in 2014 by Alex Graves) is a recurrent neural network architecture with an external memory store. Reads and writes from and to the memory are controlled by an attention mechanism. A newer version is the Differential Neural Computer (first described in 2016, also by Graves).

The setup is not fundamentally different to the Elman networks or Long-Short Term Memory networks other than the mechanism by which "memory" is manipulated and storage, retrieval or discarding of "memories" is decided, although the mechanisms are very similar too (for instance, in LSTMs, you could say that training a network to decide when to "recall" a weight value is essentially similar to the "attention" mechanism).

Is there a significant difference between an LSTM-based neural architecture with a "reverberatory" memory and one with an external storage, both controlled by similar mechanisms?

I would say- yes.

Re: The Computational Theory of Mind (2015)

#40
post #33

Earlier quoted context omitted.

In principle? No question. In practice? No chance.

How would a clockwork model of the mind explain the phenomenon of consciousness (as opposed to computation)?

Your apparent consciousness is the illusion of control over your subconscious mind.
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