2016-10-13

I trust you because I don't know why

The ongoing quick and widespread development of neural networks and deep learning systems is triggering many debates and interrogations both practical and conceptual. Among various features of such systems, the most arguable ones are certainly inscrutability and fallibility. A deep learning system builds up knowledge and expertise, as natural intelligence does, by accumulation of experience of a great number of situations. It does better and better with time. But the drawback of this approach is that you can't open the box to understand how it achieves its expertise as you would do with a classical step-by-step algorithm (inscrutability), and the expertise is not 100% proof, it's bound to fail from time to time (fallibility). I've written on some philosophical aspects of those issues, and how they relate to ancient Chinese philosophy (in French here). 

A recent article in Nature entitled "Can we open the black box of AI" presents a very good review of those issues. And the bottom line of this article comforts me in the opinion that either all this debate is moot, or that it is not linked to this specific technology, and not even to any kind of technology. All the debate is to know if we can trust something we don't understand and which is, moreover, bound to fail at some point. This seems to fly in the face of centuries of science and technology development all based on understanding and control. 

Do we control and understand everything we trust? Or more exactly, do we need to understand and control before we trust? Most of the time, no. As children, we trust our parents and adult world to behave properly without understanding the why's and how's of this behavior. And if, growing up, we start trying to question those why's and how's, it might happen that for some reason we lose that trust. When I trust a friend to achieve what she promised, I won't, or a least I should not, try to control and check if she will do it or not, and how. Trust, in fact, if exactly the opposite of control. You trust because you can't afford to, or have not the technical or conceptual tools to, or simply believe it's useless, counter-productive or simply rude to understand and control.
That line of thought applies to more simple things that people. If I cross a bridge over a river, I don't check, and do not understand, most of the time, how it's built. I begin to check it if for some reason it seems poorly built, or rotten, looking like no one else has used it for ages. You trust food you eat because you trust your provider, you generally don't check the food chain again and again. You start to check when you suspect this chain to present some serious point of failure. It's not check before trusting, it's check because for some reason you don't trust anymore. The other way round is called paranoia.
Most of the time, you trust things to work safely as expected because so far they mostly did work safely. Based on experience, not logical analysis of how it works.This includes, and actually begins with, your own body and brain. Looking further at the world around you, you discover black boxes everywhere, and it's all right. Starting to check and control how they work is likely to lead you in some infinite recursion of effects and causes, and you will either reasonably stop at some point saying "well, it's gonna be all right", or pass the rest of your life lost in metaphysical and ontological mist, and fear of any action.
Let's face it. We trust before and without understanding and controlling. Every second of every day. And most of the time it's OK. Until it fails, at some point. We know that it will. We trust our body and brain in order to live, although we know they are bound to break down at some point. We are aware that things and people we trust are bound to fail once in a while. That's just how life goes. Parents have a second of distraction and a child dies crossing the street. Friends are stuck in a traffic jam, don't show up on time and miss their flight, bridges collapse in sudden earthquakes, hard drives break down, light bulbs explode, lovers betray each other ...
Despite of our awareness of such risk of failure, we keep trusting, and call this hope. Without trust we lose hope, and fall into depression and despair. This is a basic existential choice : trust and live, or try to control and understand everything, ask for total security, and despair because you can't find it. We trust each other although, and actually because, we don't know why. And knowing that each of us will eventually fail some day, if only once at this ultimate individual failure point which is called death, should make each of us more prone to forgiveness. 

Let me borrow those final words from the brand new and unexpected Nobel Prize in Literature

Trust yourself
Trust yourself to do the things that only you know best
...
Trust yourself
And look not for answers where no answers can be found
...