So this happened, and it's
one of those rare things that when it does happen it reveals fascinating things
about humans. I just joined a Mensa debating forum containing what
seemed like a few select, intelligent people, and just as I was given access by
the admin, a woman called Amber happened to start a thread with her opening
statement - a statement that was definitely wrong.
So, maintaining politeness
at all times, I made a statement that was definitely right and contrary to what
she had reasoned, and subsequently a couple of people joined the thread to tell
me how wrong I was. Then after explaining to them where they were going wrong,
they were so shocked at what I was saying they accused me of being a troll and
within 20 minutes the admin had banned me! By then there were about six
contributors + Amber, all thinking I was saying what I was saying to wind them
up, when actually I was explaining what are, admittedly counter-intuitive, but
absolutely correct points.
It is fascinating when you
meet people who are so confused that the opposite of their falsity (the truth) seems
so bizarre that they mistake you for a trolling nutter who is not even worthy
to remain in the group.
Those that want to know
what the discussion was about will be pleased to know that I copy and pasted
all the text before losing access to the group, and put the meat of it in this
blog post I just created. It's a funny old world!
There is only one negative
thing that comes from having frequent sexual encounters with multiple partners
- there is more chance that sexually transmitted diseases will be passed on.
(Opening statement in a Mensa group. from a lady called Amber)
Realising that that is not
just wrong, but the opposite of the truth, I responded with:
Actually, no, there is only one positive
thing that comes from having frequent sexual encounters with multiple partners
- there is less chance that sexually transmitted diseases will be passed
on.
Here is how the rest of
the conversation went.
Amber: Do pray tell James how?
JK: Here’s
how it works - the more people in the promiscuity pool, the more people having
one night stands, which means those infected have a reduced chance of having
sex, which equals a reduced chance of the infected ones passing on their
infection. It is counter-intuitive, but many true things are. It may seem
intuitively that the more people you have in a pool of people who are having
sex when one has an STD, the more people end up having STDs, but precisely the
opposite is true! The more people you have in a pool of people who are having
sex when one has an STD, the fewer people end up having STDs. It's a simple
case of numbers - the more people in the pool, the greater the competition, so
the greater likelihood that Mr. infected won't pass on his DNA.
Ronald:
Maybe this is true on the first go-round. However, that one person
infects at least one other -- then you have two others with an infection to
spread, and they infect two others... You begin to see the logical progression
there?
JK: But that
isn't correct, and here's why... I'll try to explain it in a bit more detail -
first I'll show you with the mathematics, then I'll back it up with an analogy.
THE MATHEMATICAL REASON:
Suppose you go for a night on the town full of people on the pull. That is what
we've called the 'pool' - and it consists of, say, forty people; twenty are
infected, twenty are uninfected, and you don't know which is which. This means
you have a 50-50 chance of finding a safe partner. Now let's say that next
weekend the same forty people are out, but it's the annual carnival, where an
extra one thousand people are out on the pull. You now have about a 1/25 chance
of finding a non-safe partner - hence, the more people you have in a pool of
people who are having sex when a few are infected, the fewer people end up
being infected. Further, you mustn't mistakenly think that every single person
is going to get lucky - the pool won't facilitate everyone's success
(mathematically it's almost impossible) - so by adding more to the pool you
increase the number of safe people, and thereby reduce the chances that the
infected people will get lucky and thus pass on their DNA.
THE ANALOGY: Think of it
in terms of pollution - pollution is when a pernicious external force finds its
way into a benign or neutral system (it could be ecological, physiological, or
whatever). Having a smaller pool is analogous to increased pollution because
(to put it bluntly) by not being in the pool the uninfected majority would
diminish the chances of an overall de-pollution. Or if you prefer, the
pollution rates are greater with a smaller pool. If you are one of the
recklessly promiscuous people with a high probability of being one of the
infected you add pollution to the pool every time you ingratiate yourself into
it. If you are one of the infected, your chances of pulling are decreased by
the greater numbers in the pool, because competition for mates becomes fiercer.
Let's now put this into
practice by looking at your statement and seeing which way the logic takes us.
You said: "Maybe on the first
go-round. However, that one person infects at least one other -- then you have
two others with an infection to spread, and they infect two others... You begin
to see the logical progression there?"
Now then, you are right
that one person infects at least one other, and you are right that you then
have two others with an infection to spread. But looked at carefully you should
be able to see that your statement vindicates me, not you. The reason is this;
what would make the pool safer and less polluted - by making it smaller? No,
that will only make it less safe and more susceptible to pollution. But if we
do what I said the logic dictates and add more people to it, we make pollution
less conducive - thus we have a safer pool.
Amber: James your scenario is unsound. It assumes that your
small group will be heavily infected, and a large group will be strongly
uninfected, thus diluting the infected group. But there's no valid reason to
assume your starting assumptions.
JK: Amber, I'm
afraid you're mistaken - what I've said is not to do with forecasts about the
difference between a small and large group's infection rate. It is to do with
more people lowering the probability that the infected ones will get the chance
to pass on their infection.
Ronald: But if you pick 20 random people from
the population and have sex with one, or pick 1,000 people at random from the
population and have sex with one, your odds of encountering an STD are exactly
the same.
JK: This is
another mistaken approach because it requires an assumption based on no
background information. But with the above example you do have background
information - you know that the people entering the pool are low risk entrants
because they are not promiscuous. I have explained this in my last post - the
logic is correct, and its veracity is self-evident because it is based on mathematical
facts.
Ok, look, you mustn’t
think of the non-promiscuous people having lower probability than the
promiscuous people, because you’re forgetting my original claim – that an
increased pool of promiscuous people would reduce the spread of infection.
That’s the point – we are saying the whole pool is now promiscuous, so you
cannot simply imagine that it is only the infected people who are promiscuous.
The reality is, the pool
is full of promiscuous people, and the more people that enter it the less
likely that infected people will spread their infection. Pretend you are one
new person in the pool, and you have been sexually cautious in the past. It's
great for the pool that you've decided to become promiscuous. Your presence in
the pool is good on two counts (probabilistically): if you pull an uninfected
partner you divert that partner from a potentially more precarious tryst; if
you pull an infected partner you divert that partner from giving it to someone
who might spread it at a more proliferated rate than you. Rinse and repeat that
cycle every weekend! ;-)
It's not just that the
individual's chances of safe sex are greater, it is also the case that a larger
pool = the less likely that infected people will spread their infection! It's a
100% mathematical fact of conditional probability. You keep mistakenly assuming
that every single person in the pool is going to mate every single time, when
I've already said that's not the case.
Louis: "having frequent sexual encounters with multiple
partners - there is less chance that sexually transmitted diseases will be
passed on" says James Knight. I think we have a troll in the midst, only
an attention-seeker would make such a ridiculous claim.
JK: Yes, it
could be that I'm just trying to seek attention from a bunch of people I've
just met and with whom I'm only ever going to have the weakest of social ties,
or it could be that, in actual fact, everyone who has contributed to the thread
thus far is not quite yet seeing why what I've said is right. I believe that
what I’ve said already in this thread more than comprehensively conveys the
truth of my claim. I grant you, though, it is somewhat counter-intuitive, and
is perhaps akin to a circuit board epistemology where one sudden eureka light
can light up the whole situation, leaving you wondering how you missed it to
begin with. I suppose these things require a bit more wrestling with precisely
because they are counter to our intuitions. Our minds have not evolved to
accept counter-intuitive notions very easily - and when one considers things
like, say, monotonic voting systems, 0.999 denoting a real number that can be
shown to be 1, water being heavier in liquid form than in solid form, the Monty
Hall problem, and things of that nature that confound the more intuitive
feelings, one understands why a crowd can pull together and argue in the
opposite direction.
The picture makes sense to
me because, as I said, I imagined a heuristic model in which infection was seen
in terms of pollution. In this instance the pollution model meant that a
counter-intuitive notion was quite clear. What I've argued is not incorrect -
perhaps it requires you to gather it together in a different way - but whatever
works for you really. Once you think of it in terms of economics it's fairly
obvious really - that if you are a frivolously promiscuous individual with a
high probability of causing infection, you are going to pollute the partner
pool every time you enter into it with the intention of promiscuity — and for
the good of the pool you should be discouraged, just as anybody causing
pollution should be discouraged. Therefore, the corollary of that - arguing
with the signs reversed - is that that if you are a very circumspect individual
with less propensity for promiscuity and a low probability of infection then you
are going to improve the quality of the partner pool every time you enter into
it. Evidently, in the case of the latter, that’s the opposite of causing
pollution, and it would make the pool less polluted - the more of these types,
the merrier - for precisely the same reasons that pollution should be
discouraged.
Amber: Your whole argument is surely set on the faulty
assumption that there's a reliance on the external forces diluting more than
helping it spread, is it not?
JK: No
Amber, it has precious little to do with the extent to which external forces
dilute, it is to do with rates at which infected people copulate, and an
increase in pool size reducing the rate, where everyone in the pool is equally
promiscuous. More people in the pool, more competition, less success for the
infected ones. Hence, my above comment. If you keep increasing the pool
further, you will keep diminishing the chances of one of the infected ones
pulling a mate, because statistically more of the safer people will pull (this
is the nature of probability). You'll keep making the pool safer by adding more
fresh promiscuity to it, because those additions will increase the competition
further, and continue to lessen the probability that one of the infected will
get to pass on his or her DNA on any given night! The competition means that
they will pull less frequently. Which means they will get the chance to pass on
their infection less frequently. Add even more to the pool and this infrequency
is more probabilistic, and so on.
Louis: Yep definitely trolling.
JK: Or in
other words, Louis, you don't have a comeback because this conversation is over
your head, so you resort to crass, baseless accusations. Look it's fine if you
don't get it - like I said, some counter-intuitive things require a bit more of
a lateral approach, but if you think about it carefully you will be able to arrive
at the same conclusion I have.
Ruedi: If I understood James Knight correctly, I think his argument
works as long as he can keep the sample population expanding at a faster rate
than the infection rate. That's not really a feasible approach - sooner or
later, the population will reach infinite or somewhere near that, and at that
point, the infection risk will catch up and neutralize earlier gains
JK: Hi Ruedi, thanks for an
attempt at least at some kind of sensible engagement. I think you nearly got it
right when you said "his argument
works as long as he can keep the sample population expanding at a faster rate
than the infection rate", but then you go off track by saying "That's not really a feasible approach
- sooner or later, the population will reach infinite or somewhere near that,
and at that point, the infection risk will catch up and neutralize earlier
gains."
No, no it won’t. You're missing the vital
component in the equation, which is increased competition. As the percentage of
infected people is reduced (or equivalently we add more uninfected) there is
less chance that they have sex because competition is greater. This could even
eventuate in a situation where there is only one infected person who as the
group increases in size never gets look in and is thus squeezed out, never
seeing intercourse. If you keep adding fresh blood to the pool it is likely you
will have a situation where the infected percentage actually goes down as they
die off and fail to breed new germs by passing them on. How do I know that? Because
that is exactly what happens in biological evolution where alleles get fixed in
a population in evolution and others die out. What my pollution model
shows is that there exists some critical value of the percentage of the
infected where it starts to increase – it’s what’s call the tipping point; on one
side of the tipping point the infected percentage goes down and on the other
side it goes up – we just need more and more fresh blood to ensure the infected
percentage continues to diminish.
Louis: I just cannot believe you've got us all engaging in
dialogue about a ludicrous claim that more people in a pool where because of
sexual activity diseases will spread makes it more safe than when there are
less people in the pool. I'm still calling troll.
JK: Ah, still
nothing to contribute except this tiresomely narrow philosophical pez dispenser
analysis, Louis - I've all but given up on you guys. I'm not sure I can say
much more to convince if you don't already get it by now. I'm reminded of the obvservation by Charles Babbage about
having an opponent who strikes him as so confused that he is difficult to
understand - "I am not able rightly to apprehend the kind of confusion of
ideas that could provoke such a question". Ho hum!
I'll have one last crack
and then I'm outta here. What you guys have done is erroneously made an
assumption that assumes that the probability of infected person copulating is a
constant whereas I have repeatedly told you that this decreases with the
percentage of uninfected persons in the pool due to competition factors. This
in itself would lead to a reduction in the rate of increase of the percent
infection; however the absolute numbers infected would still increase.
I haven’t even needed to do this yet as the
mathematics justifies it alone – but if I wanted to present more of the real
life model I could factor in the disabling effects of the infection - that is
the infection causes a loss of the ability to breed the infection -
hence infected people are going to drop out of the copulatory pool (when most
people find out they have an infection they wilfully remove themselves from
casual sex). The infected population is subject to, not one, but two competing
rates; not just the rate of increase of new blood but also the rate at which
they fall out of the "germ breeding" pool. This means that as the
number of uninfected people increases the rate at which the
infected persons can spread the infection is less than
their disablement rate. Hence their population involved in breeding
the germ reduces. If this continues they will die out completely.
It is not that being infected significantly affects
competition, it is being in a group in which more members are added - it's not
just the infected people who are having less sex - almost everyone in the pool
is having less sex (on average) - but because the uninfected new blood
astronomically dwarfs the infected, the rate at which the infected's sex drops
is more significant than the rate at which the uninfected's sex drops - because
remember we are showing that the infection is getting diminished in the pool.
There really isn't much more I need to say in this
conversation except that everything you need to establish my opening remark -
that with more new
people in the pool there is less chance that sexually transmitted diseases will
be passed on - is contained in this discussion.
(End of discussion)
After that discussion
thread, which I'm glad I saved now, I found I could no longer access the thread
or the group, which means I must have been banned - a truly odd thing to happen
given that everyone else was getting the wrong end of the stick, and I was
actually the only one getting the right end of it. It's a crazy situation to
encounter people so unable to grasp the truth that to them the truth seems
crazy, and the messenger a troll. I suppose one is reminded of Nietzsche and
the quote about those who were seen dancing being thought to be insane by those
who could not hear the music.
Anyway,
after my ban, I decided to do a bit of research to see if anyone had undertaken
any studies on this matter - and to my (not that much of a) surprise I found that
a guy called Michael Kremer has a 54
page paper that goes into all the ins and outs of why what I said above is
the case.
There's a lot of text to
sift through, which I sped-read earlier before wring this blog post - but the
first equation on page 16 and the surrounding text is most germane to the
discussion above The first equation on
page 16 gives us the value of the rate of change of infection (the Y with a dot
over it), with the tell tale being the minus sign where the "Y dot"
is equal to the rate of increase of infection minus the death rate of the
infected.
I wish I could have survived just an extra few hours so that people in the group could have seen the proof, rather than them all thinking I'm some kind of trolling nutter who was just there to wind them up. Like I said, it's a funny old world!