"WHAT HAVE YOU CHANGED YOUR MIND ABOUT?"
of Biology, University College;
Impossible Things To Do Before Breakfast
have more many years worked on pattern in the developing
embryo formation which is the development of spatial organization
as seen, for example in the arm and hand. My main model
for pattern formation is based on cells acquiring a positional
value. The model proposes that cells have their position
specified as in a co-ordinate system and this determines,
depending on their developmental history and their genetic
constitution what they do.
development of the chick limb illustrates some of the problems.
As the wing grows out from the flank up there is a thickened
ridge of the covering sheet of cells that secretes special
proteins which we think, and this is controversial, specifies
a region in the cells beneath the ridge which we call the
progress zone. At the posterior margin of the limb is the
polarising region which secretes a protein, Sonic Hedgehog.
This is a signaling molecule used again and again in the
development of the embryo. The normal pattern of digits in
the chick wing is 2, 3, and 4. If another polarising region
is grafted to the anterior margin the pattern of digits is
4, 3, 2, 2, 3, 4.
interpretation is that Sonic Hedgehog sets up a gradient
which specifies position and with the graft there is a mirror
image gradient and Crick suggested this was due to diffusion
of a molecule like sonic hedgehog setting up a gradient.
We have worked hard to show that this model is correct.
best evidence that it maybe gradient is that if just a small
amount of Sonic Hedgehog in the anterior margin then you
just get an extra digit 2. If one increases it a bit put
a little bit more and you get a 3, 2. But is there really
a diffusible gradient in Sonic Hedgehog specifying position?
The situation is much more complex.
now think that the model is wrong as diffusion of a molecule
is far too unreliable for reliably and accurately specifying
positional values. The reasons why we think diffusion cannot
work is that there is now good evidence that a diffusing
molecule has to go between and even into cells, and interact
with extracellular molecules making it totally unreliable.
A more attractive model might be based on interactions at
cell contacts as in the polarity models proposed by others.
Position would be specified by cells talking to each other.
This is a serious change in my thinking.
Inventor and Technologist; Author, The Singularity
Is Near: When Humans Transcend Biology
I've come to reject the common "SETI" (search for extraterrestrial intelligence) wisdom that there must be millions of technology capable civilizations within our "light sphere" (the region of the Universe accessible to us by electromagnetic communication). The Drake formula provides a means to estimate the number of intelligent civilizations in a galaxy or in the universe. Essentially, the likelihood of a planet evolving biological life that has created sophisticated technology is tiny, but there are so many star systems, that there should still be many millions of such civilizations. Carl Sagan's analysis of the Drake formula concluded that there should be around a million civilizations with advanced technology in our galaxy, while Frank Drake estimated around 10,000. And there are many billions of galaxies. Yet we don't notice any of these intelligent civilizations, hence the paradox that Fermi described in his famous comment. So where is everyone?
We can readily explain why any one of these civilizations might be quiet. Perhaps it destroyed itself. Perhaps it is following the Star Trek ethical guideline to avoid interference with primitive civilizations (such as ours). These explanations make sense for any one civilization, but it is not credible, in my view, that every one of the billions of technology capable civilizations that should exist has destroyed itself or decided to remain quiet.
The SETI project is sometimes described as trying to find a needle (evidence of a technical civilization) in a haystack (all the natural signals in the universe). But actually, any technologically sophisticated civilization would be generating trillions of trillions of needles (noticeably intelligent signals). Even if they have switched away from electromagnetic transmissions as a primary form of communication, there would still be vast artifacts of electromagnetic phenomenon generated by all of the many computational and communication processes that such a civilization would need to engage in.
Now let's factor in what I call the "law of accelerating returns" (the inherent exponential growth of information technology). The common wisdom (based on what I call the intuitive linear perspective) is that it would take many thousands, if not millions of years, for an early technological civilization to become capable of technology that spanned a solar system. But because of the explosive nature of exponential growth, it will only take a quarter of a millennium (in our own case) to go from sending messages on horseback to saturating the matter and energy in our solar system with sublimely intelligent processes.
The price-performance of computation went from 10-5 to 108 cps per thousand dollars in the 20th century. We also went from about a million dollars to a trillion dollars in the amount of capital devoted to computation, so overall progress in nonbiological intelligence went from 10-2 to 1017 cps in the 20th century, which is still short of the human biological figure of 1026 cps. By my calculations, however, we will achieve around 1069 cps by the end of the 21st century, thereby greatly multiplying the intellectual capability of our human-machine civilization. Even if we find communication methods superior to electromagnetic transmissions we will nonetheless be generating an enormous number of intelligent electromagnetic signals.
According to most analyses of the Drake equation, there should be billions of civilizations, and a substantial fraction of these should be ahead of us by millions of years. That's enough time for many of them to be capable of vast galaxy-wide technologies. So how can it be that we haven't noticed any of the trillions of trillions of "needles" that each of these billions of advanced civilizations should be creating?
My own conclusion is that they don't exist. If it seems unlikely that we would be in the lead in the universe, here on the third planet of a humble star in an otherwise undistinguished galaxy, it's no more perplexing than the existence of our universe with its ever so precisely tuned formulas to allow life to evolve in the first place.
Editor. The Times, London
the public about science isn't always a waste of time —
but consulting bioethicists often is
used to take the view that public consultations about science
policy were pointless. While the idea of asking ordinary
people's opinions about controversial research sounds quite
reasonable, it is astonishingly difficult to do well.
governments canvass about issues such as biotechnology or
embryo research, what usually happens is that the whole exercise
gets captured by special interests.
vocal minority with strong opinions that are already widely
known and impervious to argument —
think Greenpeace and the embryo-rights lobby
get their responses in early and often. The much larger proportion
of people who consider themselves neutral, open to persuasion,
uninformed or uninterested rarely bother to take part. Public
opinion is then deemed to have spoken, without reflecting true
public opinion at all. Wouldn't it be better, I thought, to
let scientists get on with their research, subject to occasional
oversight by specialist panels with appropriate ethical expertise?
to a point. Public consultations can indeed be worse than
useless, particularly when the British Government has done
the consulting: its exercises on GM crops and embryo research
laws were particularly ill-judged. As Sir David King said
recently, they have taught us what not to do.
failure, though, has stimulated some interesting thinking
that has convinced me that it is possible to engage ordinary
people in quite complex scientific issues, without letting
the usual suspects shout everybody else down.
Human Fertilisation and Embryology Authority's recent work
on cytoplasmic hybrid embryos is a case in point. The traditional
part of the exercise had familiar results: pro-lifers and
anti-genetic engineering groups mobilised, so 494 of the
810 written submissions were hostile. Careful questioning,
however, established that almost all these came from people
who oppose all embryo research in all circumstances.
more scientific poll found 61 per cent backing for interspecies
embryos, if these were to be used for medical research. Detailed
deliberative workshops revealed that once the rationale for
the experiments was properly explained, large majorities
"instinctive repulsion" and supported the work.
consultations are properly run in this way, there is a lot
to be said for them. They can actually build public understanding
of potentially controversial research, and shoot the fox
of science's shrillest critics.
many ways, they are rather more helpful than seeking advice
from bioethicists, whose importance to ethical research I've
increasingly come to doubt. It's not that philosophy of science
is not a worthwhile academic discipline —
it can be stimulating and thought-provoking. The problem is
that a bioethicist can almost always be found to support any
Kass and John Harris are both eminent bioethicists, yet the
counsel you would expect them to give on embryo research
laws is going to be rather different. Politicians —
or scientists —
can and do deliberately appoint ethicists according to their
pre-existing world views, then trumpet their advice as somehow
independent and authoritative, as if their subject were physics.
specialist bioethics has a role to play in regulation of
science, it is in framing the questions that researchers
and the public at large should consider. It can't just be
a fig leaf for decisions people were always going to make
& Editor, Prospect
The nation state is too big for
the local things, too small for the international things and
the root of most of the world's ills
This was a central part of liberal baby-boomer common sense
was growing up, especially if you came from a (still) dominant
country like Britain. Moreover to show any sense of national
— apart from contempt for your national traditions — was a
you lacked political sophistication.
now believe this is mainly nonsense. Nationalism can, of
course, be a destructive force and we were growing up in
the shadow of its 19th
and 20th century excesses. In reaction to that most of the
world had, by the mid 20th century, signed up to a liberal
universalism (as embodied in the UN charter) that stressed
equality of all humans. I am happy to sign up to that too,
but I now no longer see that commitment as necessarily conflicting
with belief in the nation state. Indeed I think many anti-national
liberals make a sort of category error — belief in the moral
of all humans does not mean that we have the same obligations
humans. Membership of the political community of a modern nation
state places quite onerous duties on us to obey laws and
but also grants us many rights and freedoms — and they make
fellow citizens politically "special" to us in a
way that citizens of
other countries are not. This "specialness" of national
is most vividly illustrated in the factoid that every year
Britain we spend 25 times more on the National Health Service
do on development aid.
Moreover if the nation state can be a destructive force it
is also at
the root of what many liberals hold dear: representative democracy,
accountability, the welfare state, redistribution of wealth
very idea of equal citizenship. None of these things have worked
any significant extent beyond the confines of the nation state,
is not to say that they couldn't at some point in the future
they already do so to a small extent in the EU). If you look
at the daily news — contested elections in Kenya, death in
most of the bad news these days comes from too little nation
not too much. And why was rapid economic development possible
Asian tigers but not in Africa? Surely the existence of well
functioning nation states and a strong sense of national solidarity
in the tigers had something to do with it.
And in rich western countries as other forms of human solidarity
social class, religion, ethnicity and so on — have been replaced
individualism and narrower group identities, holding on to
of national solidarity remains more important than ever to
society. A feeling of empathy towards strangers who are fellow
citizens (and with whom one shares history, institutions and
and political obligations) underpins successful modern states,
this need not be a feeling that stands in the way of empathy
all humans. It just remains true that charity begins at home.
Computer Scientist; Chairman, Applied Minds, Inc.; Author, The
Pattern on the Stone
the Experiment Yourself
As a child, I was told that hot water
freezes faster than cold water. This was easy to refute in
principle, so I did not believe it.
Many years later I learned that Aristotle had described the
effect in his Meteorologica,
"The fact that the water has previously been warmed contributes
to its freezing quickly: for so it cools sooner. Hence many
people, when they want to cool hot water quickly, begin by
putting it in the sun. So the inhabitants of Pontus when they
encamp on the ice to fish (they cut a hole in the ice and then
fish) pour warm water round their reeds that it may freeze
the quicker, for they use the ice like lead to fix the reeds. " (E.
W. Webster translation)
was impressed as always by Aristotle's clarity, confidence
and specificity. Of course, I do not expect you to be convinced
that it is true simply because Aristotle said so, especially
since his explanation is that "warm and cold react upon
one another by recoil." (Aristotle, like us, was very
good making up explanations to justify his beliefs). Instead,
I hope that you will have the pleasure of being convinced,
as I was, by trying the experiment yourself.
Epistemologist of Randomness and Applied
Statistician; Author, The Black Swan
Irrelevance of "Probability"
I spent a long time believing in the centrality
of probability in life and advocating that we should express
everything in terms of degrees of credence, with unitary
probabilities as a special case for total certainties,
and null for total implausibility. Critical thinking, knowledge,
beliefs, everything needed to be probabilized. Until I
came to realize, twelve years ago, that I was wrong in
this notion that the calculus of probability could be a
guide to life and help society. Indeed, it is only in very
rare circumstances that probability (by itself) is a guide
to decision making . It is a clumsy academic construction,
extremely artificial, and nonobservable. Probability is
backed out of decisions; it is not a construct to be handled
in a standalone way in real-life decision-making. It has
caused harm in many fields.
Consider the following statement. "I think that this
book is going to be a flop. But I would be very happy to
publish it." Is the statement incoherent? Of course
not: even if the book was very likely to be a flop, it
may make economic sense to publish it (for someone with
deep pockets and the right appetite) since one cannot ignore
the small possibility of a handsome windfall, or the even
smaller possibility of a huge windfall. We can easily see
that when it comes to small odds, decision making no longer
depends on the probability alone. It is the pair probability times payoff (or a series of payoffs), the expectation,
that matters. On occasion, the potential payoff can be
so vast that it dwarfs the probability — and these
are usually real world situations in which probability
is not computable.
Consequently, there is a difference between knowledge and
action. You cannot naively rely on scientific statistical knowledge (as they define it) or what the epistemologists
call "justified true belief" for non-textbook
decisions. Statistically oriented modern science is typically
based on Right/Wrong with a set confidence level, stripped
of consequences. Would you take a headache pill if it was
deemed effective at a 95% confidence level? Most certainly.
But would you take the pill if it is established that it
is "not lethal" at a 95% confidence level?
I hope not.
When I discuss the impact of the highly improbable ("black
swans"), people make the automatic mistake of thinking
that the message is that these "black swans" are
necessarily more probable than assumed by conventional
methods. They are mostly less probable. Consider that,
in a winner-take-all environment such as the one in the
arts, the odds of success are low, since there are fewer
successful people, but the payoff is disproportionately
high. So, in a fat tailed environment, what I call "Extremistan",
rare events are less frequent (their probability is lower),
but they are so effective that their contribution to the
total pie is more substantial.
[Technical note: the distinction is, simply, between raw
probability, P[x>K], i.e. the probability of exceeding
K, and E[x|x>K], the expectation of x conditional on
x>K. It is the difference between the zeroth moment
and the first moment. The latter is what usually matters
for decisions. And it is the (conditional) first moment
that needs to be the core of decision making. What I saw
in 1995 was that an out-of-the-money option value increases when the probability of the event decreases, making me
feel that everything I thought until then was wrong.]
What causes severe mistakes is that, outside the special
cases of casinos and lotteries, you almost never face a
single probability with a single (and known) payoff. You
may face, say, a 5% probability of an earthquake of magnitude
3 or higher, a 2% probability of one of 4 or higher, etc.
The same with wars: you have a risk of different levels
of damage, each with a different probability. "What
is the probability of war?" is a meaningless question
for risk assessment.
So it is wrong to just look at a single probability of
a single event in cases of richer possibilities (like focusing
on such questions as "what is the probability of
losing a million dollars?" while ignoring that ,
conditional on losing more than a million dollars, you
may have an expected loss of twenty million, one hundred
million, or just one million). Once again, real life is
not a casino with simple bets. This is the error that helps
the banking system go bust with an astonishing regularity — I've
showed that institutions that are exposed to negative black
swans, like banks and some classes of insurance ventures,
have almost never profitable over long periods. The problem
of the illustrative current subprime mess is not so much
that the "quants" and other pseudo-experts
in bank risk management were wrong about the probabilities
(they were), but that they were severely wrong about the
different layers of depth of potential negative outcomes.
For instance, Morgan Stanley lost about ten billion dollars
(so far) while allegedly having foreseen a subprime
crisis and executed hedges against it — they
just did not realize how deep it would go and had open
exposure to the big tail risks. This is routine: a friend
who went bust during the crash of 1987, told me: "I
was betting that it would happen but I did not know it
would go that far".
The point is mathematically simple but does not register
easily. I've enjoyed giving math students the following
quiz (to be answered intuitively, on the spot). In a Gaussian
world, the probability of exceeding one standard deviations
is ~16%. What are the odds of exceeding it under a distribution
of fatter tails (with same mean and variance)? The right
answer: lower, not higher — the number of deviations
drops, but the few that take place matter more. It was
entertaining to see that most of the graduate students
get it wrong. Those who are untrained in the calculus of
probability have a far better intuition of these matters.
Another complication is that just as probability and payoff
are inseparable, so one cannot extract another complicated
component, utility, from the decision-making equation.
Fortunately, the ancients with all their tricks and accumulated
wisdom in decision-making, knew a lot of that, at least
better than modern-day probability theorists. Let us stop
to systematically treat them as if they were idiots. Most
texts blame the ancients for their ignorance of the calculus
of probability — the Babylonians, Egyptians, and Romans
in spite of their engineering sophistication, and the Arabs,
in spite of their taste for mathematics, were blamed for
not having produced a calculus of probability (the latter
being, incidentally, a myth, since Umayyad scholars used
relative word frequencies to determine authorships of holy
texts and decrypt messages). The reason was foolishly attributed
to theology, lack of sophistication, lack of something
people call the "scientific method", or belief
in fate. The ancients just made decisions in a more ecologically
sophisticated manner than modern epistemology minded people.
They integrated skeptical Pyrrhonian empiricism into decision
making. As I said, consider that belief (i.e., epistemology)
and action (i.e., decision-making), the way they are practiced,
are largely not consistent with one another.
Let us apply the point to the current debate on carbon
emissions and climate change. Correspondents keep asking
me if it the climate worriers are basing their claims on
shoddy science, and whether, owing to nonlinearities, their
forecasts are marred with such a possible error that we
should ignore them. Now, even if I agreed that it were
shoddy science; even if I agreed with the statement that
the climate folks were most probably wrong, I
would still opt for the most ecologically conservative
stance — leave
planet earth the way we found it. Consider the consequences
of the very remote possibility that they may be right,
or, worse, the even more remote possibility that they may
be extremely right.
Princeton; Recipient, 2002 Nobel Prize in Economic Sciences
The sad tale of the
The central question for students of well-being
is the extent to which people adapt to circumstances. Ten
years ago the generally accepted position was that there
is considerable hedonic adaptation to life conditions. The
effects of circumstances on life satisfaction appeared surprisingly
small: the rich were only slightly more satisfied with their
lives than the poor, the married were happier than the unmarried
but not by much, and neither age nor moderately poor health
diminished life satisfaction. Evidence that people
adapt — though not completely — to becoming paraplegic
or winning the lottery supported the idea of a "hedonic treadmill":
we move but we remain in place. The famous "Easterlin
paradox" seemed to nail it down: Self-reported life
satisfaction has changed very little in prosperous countries
over the last fifty years, in spite of large increases in
the standard of living.
Hedonic adaptation is a troubling concept,
regardless of where you stand on the political spectrum. If
you believe that economic growth is the key to increased
well-being, the Easterlin paradox is bad news. If you
are a compassionate liberal, the finding that the sick and
the poor are not very miserable takes wind from your sails. And
if you hope to use a measure of well-being to guide social
policy you need an index that will pick up permanent effects
of good policies on the happiness of the population.
About ten years ago I had an idea that seemed
to solve these difficulties: perhaps people's satisfaction
with their life is not the right measure of well-being. The
idea took shape in discussions with my wife Anne Treisman,
who was (and remains) convinced that people are happier in
California (or at least Northern California) than in most
other places. The evidence showed that Californians
are not particularly satisfied with their life, but Anne
was unimpressed. She argued that Californians are accustomed
to a pleasant life and come to expect more pleasure than
the unfortunate residents of other states. Because
they have a high standard for what life should be, Californians
are not more satisfied than others, although they are actually
happier. This idea included a treadmill, but it was
not hedonic – it was an aspiration treadmill: happy
people have high aspirations.
The aspiration treadmill offered an appealing
solution to the puzzles of adaptation: it suggested that
measure of life satisfaction underestimate the well-being
benefits of life circumstances such as income, marital status
or living in California. The hope was that measures
of experienced happiness would be more sensitive. I
eventually assembled an interdisciplinary team to develop
a measure of experienced happiness (Kahneman, Krueger, Schkade,
Stone and Schwarz, 2004) and we set out to demonstrate the
aspiration treadmill. Over several years we asked
substantial samples of women to reconstruct a day of their
life in detail. They indicated the feelings they had
experienced during each episode, and we computed a measure
of experienced happiness: the average quality of affective
experience during the day. Our hypothesis was that
differences in life circumstances would have more impact
on this measure than on life satisfaction. We were
so convinced that when we got our first batch of data, comparing
teachers in top-rated schools to teachers in inferior schools,
we actually misread the results as confirming our hypothesis. In
fact, they showed the opposite: the groups of teachers differed
more in their work satisfaction than in their affective experience
at work. This was the first of many such findings: income,
marital status and education all influence experienced happiness
less than satisfaction, and we could show that the difference
is not a statistical artifact. Measuring experienced
happiness turned out to be interesting and useful, but not
in the way we had expected. We had simply been wrong.
Experienced happiness, we learned, depends
mainly on personality and on the hedonic value of the activities
to which people allocate their time. Life circumstances
influence the allocation of time, and the hedonic outcome
is often mixed: high-income women have more enjoyable activities
than the poor, but they also spend more time engaged in work
that they do not enjoy; married women spend less time alone,
but more time doing tedious chores. Conditions that
make people satisfied with their life do not necessarily
make them happy.
Social scientists rarely change their minds,
although they often adjust their position to accommodate
inconvenient facts. But it is rare for a hypothesis to be
so thoroughly falsified. Merely adjusting my position
would not do; although I still find the idea of an aspiration
treadmill attractive, I had to give it up.
To compound the irony, recent findings from
the Gallup World Poll raise doubts about the puzzle itself. The
most dramatic result is that when the entire range of human
living standards is considered, the effects of income on
a measure of life satisfaction (the "ladder of life") are
not small at all. We had thought income effects are
small because we were looking within countries. The
GDP differences between countries are enormous, and highly
predictive of differences in life satisfaction. In
a sample of over 130,000 people from 126 countries, the correlation
between the life satisfaction of individuals and the GDP
of the country in which they live was over .40 – an
exceptionally high value in social science. Humans
everywhere, from Norway to Sierra Leone, apparently evaluate
their life by a common standard of material prosperity, which
changes as GDP increases. The implied conclusion, that citizens
of different countries do not adapt to their level of prosperity,
flies against everything we thought we knew ten years ago. We
have been wrong and now we know it. I suppose this
means that there is a science of well-being, even if we are
not doing it very well.