Video summary
The video begins by highlighting the dangers of science denialism, using the historical example of Thabo Mbeki, the former president of South Africa, who rejected the scientific consensus linking HIV to AIDS. Instead of accepting established medical facts, he promoted alternative cures like garlic and beetroot while denying treatment to patients, a policy that is estimated to have caused over 300,000 preventable deaths. The speaker connects this modern issue to historical precedents such as Galileo's conflict with the Catholic Church over heliocentrism and contemporary movements like flat earthing and vaccine hesitancy. These examples illustrate how rejecting scientific claims can lead to severe societal risks, particularly when it comes to public health issues like measles, which has seen a dramatic resurgence in cases globally due to declining vaccination rates.
To combat these trends, the speaker explains that understanding the nature of science is crucial, starting with a clear definition of what a "scientific theory" actually means. Unlike everyday usage where a theory might imply a mere guess, in science a theory is a robust description or story that interprets observations and facts to uncover relationships in the real world. The process of reaching such a theory relies on the scientific method, which begins with empirical observations—such as noticing how magnets attract or repel each other—and formulates hypotheses to explain these phenomena. Scientists then design experiments to test these hypotheses, accepting them as valid theories only if they consistently predict outcomes that match reality, thereby elevating a hypothesis to the status of a scientific theory like magnetic fields.
A key feature that distinguishes scientific theories from pseudoscientific ones is testability, specifically through three main principles: falsifiability, repeatability, and reproducibility. Falsifiability means that a scientific statement must be open to being proven wrong; for instance, the existence of Venus between Mercury and Earth was a falsifiable theory because telescopes could verify it, whereas a claim about an invisible teapot orbiting the sun is unfalsifiable and therefore not scientific. Repeatability ensures that the same experiment performed under identical conditions yields comparable results, while reproducibility requires that different teams of scientists worldwide can achieve similar findings using their own instruments. The video illustrates the failure of these principles with the case of Andrew Wakefield, whose fraudulent claim linking vaccines to autism was not reproducible by other scientists and was eventually exposed as a conflict of interest driven by financial motives.
The speaker concludes by emphasizing that while science is indeed a social process influenced by factors like education, religion, and prior beliefs, adhering to these strict philosophical principles remains essential for producing meaningful results with real-world impact. Although the connection between anti-vaccine sentiments and other political or social biases is complex and difficult to quantify without data, the core message is that everyone, regardless of their background, should possess a basic understanding of how science works. By grasping concepts like falsifiability and reproducibility, individuals can better evaluate claims and distinguish between valid scientific knowledge and non-scientific opinions, ultimately fostering a society that values evidence-based reasoning over conspiracy theories or denialism.
Read the full video transcript
[Music]
this is
thumb bomb becky south africa's
president between 1999 and 2008.
he became famous for its denial of the
link between the human immune deficiency
virus
hiv and immunodeficiency disease aid
despite overwhelming scientific
consensus that hiv
causes aid he suggested instead
that the causes of aids were related to
overall low levels of health care and
poverty in the country
it denied treatment to aids patients
and suggested alternative cures such as
garlic
beetroot and lemon juice his policies
are now estimated to have led to more
than three hundred thousand preventable
deaths
thunbombeki belongs to the growing
number of people trying to deny
vilify and reject scientific claims
in a movement generally referred to as
science denialism
science denial is not a new phenomenon
think of galileo galilei
an italian scientist from the 17th
century that is considered to be one of
the fathers of modern science
in galileo's time people believed the
earth to be at the center of the
universe
galileo tried to demonstrate with these
astronomical observations that the earth
and all of the other planets
move around the sun this led into a
conflict with a catholic church that
forced galileo
to deny his ideas in a now very famous
trial
unfortunately similar claims such as
that the earth is flat
are well persisting into the 21st
century flat earthers
may not pose such a big risk to society
but
unfortunately this is not always the
case
for instance established and secure
cures such as vaccines are now being put
in doubt
in a movement referred to as vaccine
resiliency
vaccinations help prevent between 2 and
3 millions
childhood death every year but the
growing number of non-vaccinated
children
is rising more than one concern
the world health organization um
declared
vaccine resiliency as one of the biggest
threats for
the world global health in 2019 and this
is even more the case
when we talk about measles measles was
an illness that was once thought to be
eradicated and is now
surging back all over the world in this
chart
you can see the number of measles cases
in the united states in the decade going
between 2010 and 2019.
it is clear that there was a huge
explosion in cases in the united states
that led in 2019 to an increase of
almost 20 times
number of cases compared to 2010.
we are witnesses of a constant
degradation of the scientific endeavor
in order to fight this trend it is
necessary to understand
what science is and why we should
believe in science in order to do so
today i would like to show you what a
scientific theory is
how scientists get to a scientific
theory and how it is possible to
distinguish between scientific
and non-scientific theories but before
doing so
it is important to understand what
scientists mean when they talk about a
theory
which is slightly different than how the
word is used in our everyday life
commonly we talk about theory as an idea
or a guess that we have about something
that has happened
and that might not be really connected
to reality in any way
in science we refer to the word theory
as a description or a story
that allows us to interpret observations
and facts
we can then play with this story in
order to uncover
relationships in the real world
but how do scientists get to a
scientific theory
let us imagine to have two magnets in
our ends once we
put them close together we might observe
two different phenomena
the magnets might repel each other or
the magnets might attract each other
imagine how to do so with more and more
magnets and always to observe the same
effect
we might wonder why do we observe such
effect
is it possible to extract a general rule
that allows us
to predict the outcome of such
experiment
what we just did was to start from a
real empirical world observation and try
to extract a general rule
this approach has been used in science
and in scientific discoveries for ages
and is known under the name of
scientific method
as just said the scientific method
starts from an empirical
observation that leads
sorry that leads to an hypothesis in our
case
the hypothesis might be that there is a
force driving the two magnets
close together or further apart and that
this force depends on the orientation of
the two magnets
once we have a hypothesis we must be
able to perform and design new
experiments
that we might prove or falsify our
hypothesis
once we get the results of these
experiments they might go into different
directions
they might deny our hypothesis and in
this case we
might need to reformulate and go through
the loop once again
or our experiment experiments might
confirm our hypothesis
and thus we would be able to elevate our
hypothesis to the role of a scientific
theory
and accept it as a valid description of
the phenomenon we are studying
in our case
the effect we observe with magnets are
due to magnetic fields and now we know
that each magnet has two different poles
a north and a south pole
same poles repel each other and opposite
poles attract each other
but what makes the magnetic field theory
scientific the crucial feature of every
scientific theory
is that we must be able to test
in the real world what the theory
predict
is going to happen this means that
we must be able to have real observation
and real experiments that prove
and show what our theory wants to tell
us
this feature is called testability and
it allows us to distinguish between
theories that are scientific
and theories that are non-scientific or
pseudoscientific
today i will focus on three different
characteristics of a testable theory
falsifiability repeatability and
reproducibility
let me start with the principle of
falsifiability once again
please bear with me because we are
meeting
a war that has a slightly different
meaning in science
than it is in our everyday life the
principle of falsifiability
states that a scientific statement is
one that could be possibly be proven
wrong
this means that we must be able to think
of a real experiment
that might show that our theory is false
the key word here
is possibly
possible means that the principle
falsifiability doesn't
state that our theory is necessary false
but only that we must be able to think
of
ways to prove it false in order to make
this principle
easier to understand let me give an
example let's pretend to have a theory
and let's call it theory number one
theory number one states that there is a
planet between mercury and earth
this theory is falsifiable indeed we can
think of
experiments that might prove whether
there is actually a planet
between mercury and earth for example
we may think of having a telescope that
looks
what is before mercury of course what we
know nowadays is that there is actually
a planet there
and it's called venus this makes the
theory
real in practice but also falsifiable
since we were able
to think of an experiment that might
might have possibly
proven our theory wrong having a theory
that is falsifiable
makes it easier for us to justify and
believe in such a theory
let's now go to the other end let's take
theory number two
theory number two states that there is a
china teapot orbiting around the sun
between earth and mars three numbers two
also states that this china teapot is
undetectable by any telescope or
technology known to human
this is of course a problem and this
makes theory number two
unfalsifiable not falsifiable
of course we cannot detect the teapot if
we
have no instrument to actually see if
the teapot is there
this makes makes it difficult to justify
and believe in theory number two
as you saw with theory number one
scientific theories are all
about taking risks we have to think of
ways that
might prove our theory wrong and then
test if the theory is actually wrong
moreover scientific theory
makes bold predictions we try to
falsify our theory and until we cannot
do that
we think of the theory to be true and we
believe in our theory
there are some there are theories that
do not take any risk
they are not falsifiable in science this
is considered to be
a weakness and not a strength of the
theory
finally let me highlight once again that
falsifiability doesn't necessarily mean
that our statement is wrong
falsifiability
allows us to keep in mind that there
could be a new observation come in the
future
that proved our theory to be wrong and
false
if this happens we would be able then to
change or modify our theory
and this is our science advances
we said that for a theory to be testable
once we have a scientific statement
we need to be able to think of
experiments and the results that might
falsify our theory
in order to get really scientifically
valid statements
these results must be repeatable and
reproducible
the principle of repeatability means
that we must be able to perform the same
experiment over and over
starting from the same observation going
through the same experimental setting
and using the same instrument
if this is possible and we always obtain
comparable results
we have a repeatable experiment
repeatability ensures that you
as a scientist can trust your own
results let me once again
go back to the example of our magnet a
scientist would be interested to take
two magnets and keep on putting them
close together in order to observe
whether then they attract or repulse
each other
based on their orientation if this
happens
the theory and the results are
repeatable
once we have a scientific statement
that is falsifiable in our opinion and
for which we have identified experiments
that might prove it
false we expect these experiments to be
universal or reproducible
this means that if we have different
teams of scientists scattered all around
the world
they must be able to start from the same
question use their
own observations and their own
instruments but get to comparable
results
once again if you want to see whether
the
magnetic field theory allows us to have
reproducible results we would have
scientists
scatter all over taking their own
magnets putting them close together and
observing whether they attract or
repulse each other
based on their orientation if this
happens the results are reproducible
we now have all of the instruments that
might allow us to evaluate whether a
theory
is scientific or pseudoscientific allow
me to
give you one last example of a very
famous
scientific misconduct case that led to
devastating consequences
and that started one of the main trend
in the vaccine residency
community that vaccines may cause autism
in 1998 british doctors
andrew wakefield stated that
vaccines that were supposed to cure
measles
mumps and rubella the so-called mmr
vaccines
were supposed to cause autism of course
this piece of news and of research
quickly spread all over the world and
led to an almost immediate drop
in vaccination rates but there was a
fundamental problem
group of scientists immediately tried to
reproduce and find whether there was
actual link between
vaccines and autism and they were not
able to
wake if wakefield's results were not
reproducible
therefore from a scientific point of
view his statement was not valid and
could not be considered
more of a normal personal opinion
eventually what was discovered during an
investigation was that wakefield was
working after being paid from a
private law firms that wanted to force a
link between vaccine and autism
in order to open lawsuits against
vaccine manufacturers
here i come to an end today i showed you
what a scientific theory is and how
common language
and scientific language may differ
i showed you how scientists get to a
scientific theory
using the scientific method finally
i hope i demonstrate that there are a
few instruments that might allow us
to evaluate whether theory is scientific
or non-scientific
and this will be whether the theory is
falsifiable repeatable and reproducible
thank you very much
thank you any questions
raise your hands there is one over there
in the front row
as you're also a neuroscientist do you
find some strong correlation between the
people who tend to go for
anti-vaccinations conspiracy theories
and
their anti-migrants as well and they
tend to be on the right side of the
spectrum if you
know what i mean of the politics do you
find a strong correlation in all of that
um
importantly what's the main reasons uh
behind it is it how their brains are
wired
also religion comes into place as well
but yeah yes
to be honest i think it's quite risky to
affirm something in that direction and i
honestly wouldn't feel like doing it
also because i have no numbers in my end
that confirm
in any direction what you have just
suggested
for sure there are different reasons for
people
tending not to believe in science and
scientific theories or in vaccines in
particular
and this might be related to
education that might be related to
religion prior beliefs
the society they are born in which of
course plays a big role
but i think it's very difficult to find
a common denominator in all of
this kind of trends and yeah behaviors
yeah i have no numbers you know so i
mean again as a scientist if i have no
numbers and especially then
deriving casual relationship is always
kind of tricky so i wouldn't
they're saying something especially now
in some situations i think that was a
great example of sticking to the
scientific method
any other questions
don't be ashamed there is one over there
um there is a little bit of idea
that sorry
um that science is also a social process
and
basically boiling it down to the the
very strict philosophical
principles is maybe not doing the real
scientific process as it happens at the
university
and in the journal of justice
how much do you think do you see this in
your own
life and in your work or in the reality
of science so to say
so i agree that often these two
aspects are considered to be quite
different and to a certain extent they
must be considered
to be different but i do
believe that in order to have
meaningful scientific results that can
have a real impact it is necessary to
have this
principle in mind and unfortunately i'm
not sure how many people actually either
in science or outside of science really
know this
this principle and that's why i deeply
believe it is necessary for everyone to
have a basic
knowledge whether you're in science or
not doesn't really matter
to have a an understanding of what it
actually means
to do science or to do experiments
thank you for this answer i would advise
you to
find him after the event for your other
questions as our time
for questions on the stage is up so
thank you very much i would
give him a warm applause
[Music]
you