Bayesian Ethics

As I’ve written before, one of my past wrestles is with Utilitarianism: that the moral act is the one with the best consequences regardless of what rules it breaks. I’m now firmly Aristotelian – aka a ‘virtue ethicist’ – we are what we repeatedly do.

But Anthony Appiah the Princeton Philosopher has some challenging things to say about virtue ethics in a Philosophy Bites podcast – including some experiments. And I’m inclined to listen. I like a bit of scientific method.

I like Appiah’s ‘Cosmopolitanism’ too which has helped me articulate my ‘live and let live’ theory of internationalism at work. Humans value culture. Different cultures value different things. And Cosmopolitanism says, short of harm, we should let them. Which I think is about right.

Appiah challenges virtue with ‘experimental ethics’ – seeing what people actually do, rather than what we theorise, and looking inside people’s heads in brain scanners. He finds, for example, nearly everyone gets more generous to strangers if they find a suitably planted $10 note on the floor.

His conclusion is that the idea of a ‘moral’ person in the Aristotelian sense is not borne out by the experimental reality. For him, we make moral choices based on context, stimulus and ‘in the moment’ not based on ‘character’. I don’t entirely agree, but it’s interesting stuff.

Learning to use the head to override the instinctive ‘yuk’ response or being over-influenced by the situation is one of the things he advocates. But only sparingly. Here’s where rules, norms and culture – plus a moral education – might help. But he’s not for becoming too calculating.

He disagrees with Utilitarianism for example. First, because it doesn’t capture the experimental reality of how we respond to moral situations. Second, because were to implement calculating ‘consequentialism’ wide-scale it would dramatically impoverish human existence. Largely because promoting purely rational calculation would tend to demote difference and different views.

Cultural Cosmopolitanism makes life interesting and liveable. And if you’re going to accept difference in culture you have to accept it in worldview and ethics too. That people care about different things is what makes people interesting – and maddening.

I personally think virtue and ‘outlying’ single instances of behaviour are not incompatible. I don’t doubt that you can get very good and very bad moral choices and behaviours out of me if you significantly change my conditions and stimuli.

I also think that the prospects of me making better or worse choices are determined, yes, by the context and circumstances – but crucially, combined with who I am. And who I am is the product of a life lived, previous choices made, data, concepts and theories within and Bayesian probability mashing all that together in a nano-second every time I act.

I think there is ‘virtue’ and I have a ‘character’. It’s just that the complexity of the probabilistic calculations – all done subconsciously by that marvel of existence, a human brain – mean Utilitarianism is too crude and individual ethical experiments are too simple to anything like capture them. I return to my own dictum – if the human brain were simple enough to understand, we’d be too simple to understand it.

So I like Appiah’s ethical experiments – they deserve a well signposted place in my Bayesian brain’s data set – and I’ve shared then with others too to influence them. But virtue, character and Aristotle’s ‘I am what I repeatedly do’ still work best for me. Thanks to Appiah though, I’m also a Cosmopolitan. So I’m delighted to weigh a well-wrought difference of opinion in the Bayesian ethical balance. It all goes in the mix.


I was reminded of one of my own ‘mottos at work’ this week – don’t start with an apology. We often start an encounter by excusing ourselves for things that aren’t really our fault. That, or making an unduly self-deprecating comment. Why?

Well when it comes to a big ballsy idea you can’t beat Nietzsche. What say you to this: all our animal instincts that don’t get let out into the real world get turned inside. This is Nietzsche’s idea that our ‘will to power’ is either expressed externally or turned in our ourselves – often as guilt.

Nietzsche is an interesting chap. Unashamedly elitist, cultured, a fine writer. But also discomforting and highly speculative. His punt – based on no particular evidence it must be said – is that there was a time when we were cruel but cheerful. Guilt didn’t exist. Just debts to repay and retribution to enact.

Depending on whether you were owed to or in debt, you were either cheerfully duffing someone up or being duffed up. But there were no hard feelings – even if it was painful and cruel. The nobly savage, jolly, barbarian life.

This reminds me of the Viking laws someone gave me a copy of a couple of years ago:

Be direct, brave and aggressive, grab all opportunities, use varying methods of attack, be versatile and agile, attack one target at a time, don’t plan everything in detail, use top quality weapons, keep weapons in good shape, keep yourself in good shape, find good battle comrades, agree on important points, choose one chief.

Not much introspection there. Sensible organisation, plenty of ‘flow’ potential and a good deal of what we would consider cruelty. I also suspect not much guilt… And by the sounds of it a fair bit of cheerfulness.

And this is what I find interesting in Nietzsche’s thesis. The barbarism and cruelty of dominance and power led to vivid, guilt free lives – nasty brutish and short no doubt, but vivid and guilt free. For Nietzsche, guilt is simply energy we can’t expend elsewhere. So why do we all feel guilty all the time?

Because we can never do enough (Kierkegaard) if anyone could view what we’re doing as wrong then it is wrong (Kant) and even when we do do the ‘right’ things they may turn out wrong (Mill).

Nietzsche asks a perfectly good question; why do we feel so guilty for everything? These days I’m feeling less guilty about spending that energy better elsewhere.

The Good Life

I used to be a strict Act Utilitarian – the moral act is the one that produces the most overall happiness or least harm. The undergraduate philosophy case studies all seemed clear cut to me.

Knowing what we know now, would I have assassinated Hitler in 1934? Sure would. If a sadistic Generalissimo passed me a gun to kill an innocent in exchange for the lives of several others, would I pull the trigger? Under duress and with no alternatives, reluctantly, yes.

To my untrained late-teen moral mind, rational calculations seemed to provide a better framework than the rules of religions and imperfect man-made moral codes. Undergraduate philosophy taught me how to ‘reductio ad absurdam’ any nuance or shade of grey. Life was black and white. Add it up, make the call, don’t expect to be understood, live with the consequences.

But the pointer on my my moral compass started twitching in my mid-thirties. Act Utilitarianism can feel calculating, look immoral and set bad precedents. A good outcome is a bad justification for a rotten process. Some things shouldn’t go under the wheels as we drive hard to a destination. We have to stand for some things, or we stand for nothing. Sometimes what the head can justify sickens the heart.

Enter Aristotle in my Forties. Eudaimonia, arete and telos – flourishing, excellence and fulfilling our innate potential – they feel like the ingredients of a good life to me. There are some rules and a handful of prohibitions in Aristotle’s Ethics. But ‘moderation in all things’ is the basic gist. Thinking and talking about Aristotle this week, I have a clearer idea why I prefer the life’s work of ‘eudaimonia’, to the instant gratification of ‘happiness’, as a moral end.

Happiness is a mental ‘state’. In eras where life was nasty, brutish and short it must have been pretty rare. Perhaps no surprise then that ‘happiness’ bubbled to the surface with Bentham and Mill as the ‘Dark Satanic Mills’ were robbing people of eudaimonia and the ‘telos’ of crafts and village life. William Blake, whose poems I’m reading at the moment, gives a flavour of this in ‘Songs of Innocence and Experience’.

But in the affluent, materialist, 21st century Western world, I fear happiness is a false god. Sex, drugs and rock ‘n’ roll put transitory hedonistic pleasure on an altar. Thinking about this, I was reminded of another undergraduate philosophy ‘thought experiment’ – the brain in a vat. What if all my sensations are fed me by a mad scientist thorough electrodes plugged into my brain?

Here in the ‘real’ world we are closer and closer to being able to live purely for audio-visual, digital and chemical pleasures without needing a mad scientist. People need to participate in their lives not plug in, switch off and get high. This is substantially Csikszentmihalyi’s case for embroidering our lives with varied challenges, new skills and personal growth.

Aristotle gives life an achievable and worthwhile end – to be the best of who we are. It is an optimistic, forgiving, perfectible, self-improving and thoroughly ‘open system’ – in his nutshell: ‘we are what we repeatedly do’.

Virtues and excellence grow with our actions, a little reflection and lots of practice. There’s plenty of room in Aristotle for happiness – especially through friends. There’s an explicit acknowledgement of ‘flow’ – the work of the harp player is to play the harp, and of the good harp player to play the harp well. But above all the good life is the one we lead every day by growing, improving, refining, learning, reflecting and acting.

I think Aristotle trains core moral strength better than the rational calculation of Utilitarianism. Better to act, learn, feel and constantly improve than use intellectual brute force to calculate the answers. Life is more Bayesian than arithmetic, more non-linear than deterministic. It’s a life’s work to work on the answers for myself – and to enjoy the journey.


I studied philosophy at Oxford and in ethics was drawn to John Stuart Mill and Utilitarianism. Human happiness as a basis for morality seemed more attractive than rules and commandments and all the thought experiments seemed to suggest the ‘right’ thing to do drops neatly out of weighing all the consequences of your actions and choosing the course with the best or least worst consequences. Great.

The problem is I’ve increasingly realised for me it doesn’t work. Why? In truth I have to admit I first realised I had a problem because utilitarianism looks bad. When people see you weighing ‘secular’ values, like money or resources against ‘sacred’ ones like the value of a life or rights or fairness it ‘feels’ wrong. And here is the clue I think. It feels wrong.

Listening to a Philosophy Bites podcast I heard someone say the job of ethics is to accurately describe our innate ‘felt’ sense of what is right. When I first heard it I thought it was plumb wrong. I thought the job of ethics was to lay down a rational, internally consistent code of behaviour and then win everyone round to living by it. The trouble is like bills of rights and codified legal systems and utilitarianism it’s too hard and there will always be exceptions and situations and messiness in human affairs which are important but don’t fit.

So I’m coming round to the view that it’s a lot simpler than I thought. Our minds are Bayesian probability engines. We take the sum total of all we know, have seen and done and form instinctive ‘gut’ judgements on things which we then test against new data. That’s how we work. Bayesian probability means following your gut on something you’ve never seen, done or know anything about may not be the best approach – get some data or ask someone.

But on things you know a great deal about, people, what’s right and wrong, what you should do and what you shouldn’t you have an amazing storehouse of knowledge and experience accumulated over your whole life, plus the cultural and biological inheritance of the entire human race since we evolved. The on the great moral questions and the big ethical choices in our lives, the ‘right’ thing to do is follow your gut, ignore your head – you know it makes sense.