When training an artificial neural network, a simplified version1 of the classic workflow is:
A direct parallel can be drawn between this process and the habit formation described by Charles Duhigg in The Power of Habit. He describes habitual behaviour as a three-step process2:
To a single neuron, this is how training looks:
In fact, the analogy also works at the level of the network as a whole:
So, from a process perspective there do seem to broad similarities between how we – as humans – form habits, and how we perform supervised machine learning on neural networks.
In Thinking, Fast and Slow, Daniel Kahneman draws a distinction between System 1 and System 2 thinking. The former is responsible for fast, cheap, lossy, inaccurate, and unconsious thought; the latter is responsible for analytical, reasoned, slow, expensive, and conscious thought.
Habits and habitual behaviour are archetypal examples of System 1 thinking: we can solve extraordinarily complex problems without even noticing it – for example driving a car while our mind wanders a little.
Some hallmarks of System 1 thinking are:
The similarities between these attributes and the behaviour of trained neural networks are striking.
Admittedly, I cherry-picked these attributes to some degree but – apart from certain human-centric cognitive errors that we suffer from – it’s hard to find a single characteristic of System 1 thinking which isn’t also evident in artificial neural networks.
Kahneman doesn’t imply that his System 1/2 abstraction represents an actual underlying psychophysiological distinction: both systems are powered by the same underlying hardware – neurons – after all. On the other hand, fMRI experiments show that System 2 is associated with increased frontal and parietal cortex activity, so perhaps there really is a structural difference between the two systems.
Whether there is a physiological distinction between the systems or not, it seems clear that there is a wide spectrum along which cognition can happen – with System 1 at one end and System 2 at the other.
As described above, supervised machine learning looks to be at the same end of that spectrum as System 1: from both a process and behaviour perspective.
The two clearest conclusions from this are:
AGI is a dream or a nightmare depending on whom you talk to.
Either way, although supervised neural networks can take you deep into the uncanny valley, it seems like there will always be something missing if they just get better and better, faster and faster, at System 1-like responses.
Yes, we could dump out the weights of all the neurons to fully “explain” a neural network. However, in the same way as performing that procedure on a human wouldn’t “explain” their personality, we don’t gain real insight from merely understanding the hardware.
There has been some progress on generating commentary alongside a particular decision but its domain is very limited. Many leading AI researchers have shifted in recent years to focussing on the statistical outcomes of the AI and optimising there – rather than demanding a wholesale account of each individual decision.
Neural networks just don’t work in a logical, considered way which can be dissected and analysed afterwards. There is no rational answer to be explained so it would behove us to stop asking the question.