The many ways in which scientists study the natural world

It is presumed that there exists a great unity in nature, in respect of the adequacy of a single cause to account for many different kinds of consequences. 
                                                                                                                                                                  Immanuel kant

Introduction

The natural sciences aim to acquire knowledge about the natural world. The scientific method is a key feature of what makes the natural sciences so scientific. The underlying methodology that ​binds all disciplines within the natural sciences together is so important that we may even use it to distinguish "real" or "good" science from "bad" science and even pseudo-science. Within this method, evidence and justification play a very important role.  Each discipline within the natural sciences aims to produce knowledge about different aspects of the natural world. In this sense, each discipline within the natural sciences will tweak its methodology somewhat to fit its particular purpose and scope. Nevertheless, all disciplines within the natural sciences will broadly have a shared underlying scope, methodology and purpose.
At this point in time, we tend to place much trust in the natural sciences. "Scientific proof" has almost become some sort of guarantee of the quality or veracity of knowledge. Unfortunately, this trust can be abused. The cosmetics industry may seduce you to buy their latest anti-wrinkle cream by fiddling with statistics and plastering "scientific sounding language" on the packaging of its products. Research funded by entities that benefit from its findings will often eliminate inconvenient data and truths. If a study (albeit indirectly) funded by a multinational oil company, for example, claims that climate change is not real, we have reason to doubt the quality of its knowledge. In this sense we should also approach "scientific research" on products sold by pharmaceuticals with caution. It is worth remembering that knowledge from the natural sciences is not necessarily correct, simply because it is scientific. The natural sciences have come a long way since they originated in Ancient Greece (or earlier- depending how you start counting), both in terms of knowledge production and methodology. Our current understanding of the natural sciences and its methodology is primarily based on the most recent developments of the area of knowledge within the last few centuries. Much knowledge that was previously considered scientific, has now been discarded. If your doctor would use Hippocrates' humor theory to diagnose a tumour, you would probably be outraged. As knowledge within the natural sciences develops, some incoherent knowledge gets discarded and at times even paradigm shifts occur. The natural sciences are in se open to scrutiny, because peer review and falsification are currently part of its methodology. At this point in time, there are some shared methods and values that underpin the nature of knowledge production in the natural sciences. However, these values and shared methods within the scientific community might change over time. In this sense, it is difficult to predict how knowledge within the natural sciences will evolve.
We are now at some sort of turning point in history, where we are able to manipulate the world around us to the extent that it defies human boundaries. Increased scientific knowledge comes with great ethical responsibilities. It is not always easy to establish possible criteria that help us decide whether knowledge acquisition in the natural sciences is ethical or not. These ethical considerations might perhaps pose one of the biggest challenges for the natural sciences in the years to come.

Reflection: How would you translate the word "science" into your language? What does the nuance of your translation imply?

The value of scientific knowledge

The natural sciences currently enjoy a great status. This is partly due to its relatively recent successes and achievements. The contributions of the natural sciences to knowledge as a whole are undoubtedly enormous. Fascinating scientific discoveries have helped us understand human nature better, grasp how our planet has evolved and even conceive what the universe may look like. The natural sciences give us so much knowledge that they almost seem to overshadow all other areas of knowledge. Western civilisation went through a major cognitive paradigm shift around the 17th Century. Discoveries by Galileo and Newton challenged the prevalent dominant discourse. A new theory of knowledge primarily based on empirical evidence and reason was created. Scientific evidence soon became synonymous with 'ultimate proof' and religious knowledge was challenged by scientific sceptics. This scientific revolution brought about major changes in the way we thought about the world, particularly in the West. Mankind arguably benefited in many ways from this cognitive paradigm shift and with an increased understanding of the world around us, living standards and arguably education generally improved. Yet, the natural sciences were not always as highly regarded. There have been cases were scientific hypothesis were seen as ludicrous and even dangerous because they did not fit within the dominant way of thinking (cognitive paradigm). Science had to fit in with the world view of the time and not the other way around. Scientists who dared to propose knowledge that was different were often ridiculed (like Darwin) or tried by the inquisition (like Galileo). Nowadays it seems that the tables have turned. Once upon a time, some scientific discoveries were rejected because they did not fit in with the paradigms of religious knowledge systems. Nowadays, some people reject (their) religion because it does not fit in with the scientific way of thinking. Although the natural sciences have undoubtedly made enormous contributions to knowledge as a whole, we may question whether this necessarily means that the natural sciences offer better quality knowledge than other areas of knowledge. To answer this question, we first need to look at what constitutes good science, how the natural sciences work and what they can produce knowledge about.

​Reflection: Why might some people regard science as the supreme form of all knowledge?

Distinguishing good science from bad science

How might we distinguish good science from bad science?
Under what circumstances should we be suspicious of scientific findings?
What criteria could we use to distinguish science from pseudo-science?

We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science & technology.
Carl Sagan

Lots of scientific knowledge you have personalised throughout your education is in fact second hand knowledge. You acquired this knowledge mainly through language, either via a textbook or the words of your teachers. You arguably trusted your teachers and believed that what they told you in science class was true. But under which circumstances should we accept second hand scientific knowledge? The motto of Britain's very first scientific society  (The Royal Society)  is "Nullius in Verba", which means "Take nobody's word for it".  One of the key features of the natural sciences is the necessity of being able to prove what you claim. Good science does not only require proof. It also actively invites peer-review and even falsification. For example, if your teacher claims that starch will turn blue when mixed with iodine, you will want to test this yourself. Within the natural sciences, you should be able to repeat experiments to see if a hypothesis is correct. But what should you conclude when an experiment 'does not work'? If this happens in you science lesson, you may have made a mistake. Perhaps the conditions were not exactly the same as what the experiment had in might, which may have led to different results. However, if you are a practising scientist and your experiment shows that a hypothesis from another scientist does not work, you may be on to something. Maybe the hypothesis of the other scientist was not correct, or you could have discovered particular conditions in which the experiment does not work. In that case, knowledge from other scientists may need to be refined, built upon or even discarded (when proven wrong). Some scientists do not conduct their studies correctly and they may dispose of inconvenient data. When scientists are not open to peer-review, we should approach their knowledge with caution. There are circumstances in which experts get it wrong. This can be because they deliberately created erroneous knowledge, to seek fame or financial gain. Andrew Wakefield, for example, deliberately tweaked the findings of his research to claim that MMR vaccines cause autism and Crohn's disease. He published these findings in respectable journals such as The Lancet. The scientific community, however, soon found that there were ethical and factual problems with his methodology. Incorrect scientific knowledge can surface for a while within the scientific community, but over time, these ideas are (hopefully) phased out through peer review. Wakefield's claims have now been discarded; The Lancet retracted the original article and Wakefield is not allowed to practise medicine anymore. Nevertheless, fear amongst the wider (not scientific) population led to a decline in vaccinations, with disease and mortality as a negative consequence. False scientific knowledge can become widely accepted by the larger community, as this community is often unable to distinguish good science from bad science. Ben Goldacre points out how 'bad science' permeates popular culture and belief. Should we perhaps be wary of scientific knowledge claims (in media) which rely too much on emotive language (often fear)? ​When it comes to distinguishing good science and bad science, it is important to check the funding of research as well as the possible profitable nature of its findings. Ben Goldacre explains in his TED talk, how the pharmaceutical companies can play with statistics and inconvenient findings to prove the efficiency of their medication, for example. 
Moving on from bad science, we can also be confronted with pseudo-science. Pseudo-science may on the surface look like real science, as it aims to present itself that way. However, a key feature of the natural sciences is that scientific claims can be tested. The latter is not the case for pseudo-science. The history of medicine as a discipline illustrates that there were times when the lines between science and pseudo-science were blurry. I would argue that with the increased quick dissemination of information through current media, pseudo-science has somewhat gained in popularity. Astrology is one of the more traditional examples of pseudo-science. It draws on confirmation bias (you count the hits and forget the misses). Its vague descriptions will ensure that virtually every loyal horoscope reader will be able to find "hits" that "prove" astrology works. The descriptions about life events and personalities offered by horoscopes are so applicable to a multitude of situations and people, that we may think they are actually catered to our particular situation.  Depending on the knowledge community you belong to, what is science to some, may be pseudo-science to someone else. Where would you place graphology, phrenology, acupuncture, homeopathy, Feng Shui, or brain gym?
Although the notions of testing, falsification and peer review play a crucial role in distinguishing good science from less credible scientific knowledge, it is important to remember that not all scientific hypotheses can be tested in the same way. Sometimes evidence is not available (yet), because we do not have the means to observe things that are too small for current technology to "see", or perhaps simply too far away. In this sense, we should not automatically discard all scientific knowledge that cannot be tested in a laboratory. Nevertheless, it is very important to check the sources and methodology used to produce knowledge that claims to be scientific.

Methodology

Scientists try to "map" the natural world. This map tries to describe, predict and explain different essential aspects of the natural world. To produce knowledge about the natural world, scientists currently use a particular method: the scientific method. This method is based on observation and hypothesis, which is tested (through experimentation). Scientists may formulate a law and/or a theory, both of which explain things about the natural world. A scientific law "predicts the results of certain initial conditions" (Matt Anticole at TEDed). In short, it predicts and explains what will happen. A scientific theory, on the other hand, "provides the most logical explanation as to why things happen as they do". In short, it explains why things happen. Sometimes scientific laws stand the test of time, whereas theories don't. Kepler's laws of planetary motions, for example, are still used today, whereas his theory of musical harmony has now been replaced with the theory of gravity to explain why the planets move the way they do (see TED ed, theory versus law). 
To verify the reliability of your hypothesis, you (and others) should ideally be able to repeat your experiments. Repeating experimentation may help us accept that something is right. In theory, this seems feasible within the natural sciences, because the natural world can arguably be verified empirically. However, some great scientific hypotheses cannot be tested through experiments based on observable data. Our sense perception is not perfect, and despite the enormous advancements in technology, we cannot observe as much as we would like to. It is also practically impossible to repeat experiments infinitely. In that sense, Popper proposed that scientists try to falsify (prove wrong) each others' ideas and findings. For example, if a scientist claims that metals expand when heated, other scientists are invited to actively prove that this is not true. They could look for situations in which metals do not expand when heated. This process of falsification aims to ensure the validity of scientific knowledge. It may also lead to the improvement of scientific knowledge, as theories can be refined, for example. Nevertheless, the processes of falsification as well as verification are limited. This is partly due to problems with induction, reasoning and observation, which all play an important role within the scientific method.
Reason and observation (through sense perception) are very much key to the scientific method. We use inductive reasoning to come up with a hypothesis. We observe things around us and pick up patterns. From these patterns we may form a hypothesis that explains what happens or even why things happen. We need reason to do this. We can evaluate the validity of scientific knowledge by verifying whether the rules of mathematics and reason have been respected. We can also verify whether findings are empirically correct. But sometimes empirical data contradicts a theory and vice versa. In a way, it is very difficult to offer ultimate proof of scientific knowledge. This is especially the case if we want to create knowledge about things that cannot easily be observed. Sometimes we have to observe the effects of something rather than the thing we want to observe, sometimes the tools we use to observe (such as is the case of fMRIs) are quite far removed from a simple act of observing. Extensions such as telescopes and magnifying glasses are arguably mere extensions. But there is more at hand with fMRIs. In addition, sometimes observing is not as passive as what may appears to be the case. If we were to stick with what was easily observed and verified, our scientific knowledge would be limited. In addition, by relying merely on reason and sense perception, we may well be able to explain what happens, but we would probably be less successful at explaining why this happen.
Revolutionary breakthroughs in the natural sciences show that scientists sometimes had to take "a leap of faith". On occasion, observable evidence was not available yet. In that sense, the leap of faith relates to going beyond available evidence. For example, 100 years after Einstein predicted their existence, we now have evidence of gravitational waves. Sometimes scientists have to overcome the limits of our current frame of understanding things. They have to look at things from a different perspective and offer a more original theory than the ones that fit within the worldview at the time. In this context, it is worth remembering that imagination plays a much bigger role within the scientific method than may appear at first sight.  Helen de Cruz and Johan de Smedt argue that (progress in) science is in fact a form of structured imagination, whereby analogies with knowledge in other fields drive scientific discoveries. In fact, our intuitions about the natural world are often not very scientific at all. For example, children across the world intuitively feel that earth is flat. If no one told you that the earth travelled around the sun, your intuition would probably tell you it was the other way around. By transferring distant analogies, we can overcome these intuitions and make scientific progress through what de Cruz and de Smedt call 'structured imagination'. By using good reasoning skills combined with imagination, great thinkers such as Copernicus made important breakthroughs in the natural sciences.

Re​flection: Can we still call a discipline a natural science if we take away its scientific method?

Evidence and observation

Science is a way of describing reality; it is therefore limited by the limits of observation, and it asserts nothing which is outside observation.
                                                                                                                                                                     Jacob Bronowski

As seen previously, scientists sometimes need to take a leap of faith and propose ideas that cannot be verified yet. Sometimes we do not have the means to empirically observe the evidence we need to prove our theories. Years later, with the advancement of technology and progress in other areas, these ideas might be proven  wrong, or right. ​The latter was the case for Einstein, who predicted the existence of gravitational waves as part of his general theory of relativity. This part of the theory (gravitational waves) was widely accepted within the scientific community, but until recently, we had no empirical evidence of it yet. Nevertheless, in 2015, 100 years after Einstein's initial predictions, scientists have been able to spot the first gravitational waves.  In an article by TIME magazine, Jeffry Kluger observes that "humanity’s genius, as often happens, was a big step ahead of humanity’s machines." He continues to cite scientist David Shoemaker from MIT: “It is remarkable that humans can put together a story, and test it, for such strange and extreme events that took place billions of years ago and billions of light-years distant from us.”
Within the natural sciences we rely heavily on sense perception and reason. Advancements in technology have allowed us to create better tools to observe, but there is still much we cannot access through our (limited) human frame. Some inventions, such as the microscope, telescope and magnifying glass are arguably mere extensions of human sense perception. Others, go beyond that and "some evidence is produced by processes so convoluted that it’s hard to decide what, if anything has been observed." (plato.stanford.edu). "The role of the senses in fMRI data production is limited to such things as monitoring the equipment and keeping an eye on the subject. [...]  If fMRI images record observations, it’s hard to say what was observed—neuronal activity, blood oxygen levels, proton precessions, radio signals, or something else. [...] Furthermore, it’s hard to reconcile the idea that fMRI images record observations with the traditional empiricist notion that much as they may be needed to draw conclusions from observational evidence, calculations involving theoretical assumptions and background beliefs must not be allowed (on pain of loss of objectively) to intrude into the process of data production.'" If we need to resort to tools that go beyond mere observation through senses (because of additional manipulations and calculations), this may affect the validity and neutrality of empirical data.
Observation can indeed be less passive or receptive as what we might think. It also takes great skill and practice to conduct correct scientific observations (especially when we access tools such as microscopes or telescopes). Our assumptions and wishes may also influence what we see. If are desperate to find evidence for something, chances are we will find it. We may fall in the trap of confirmation bias or selection bias. We could count the hits and forget the misses. With inductive reasoning (which is intrinsic in the scientific method) comes the danger of hasty generalisations. We may conclude things based on insufficient observations. Nevertheless, it is not possible nor desirable to observe everything all the time. Within the natural sciences, the concept of evidence might encompass more than just empirical evidence and empirical evidence may mean different things in different situations.

Falsification and the importance of peer review Why do we need a scientific community of knowers?

Although we place  a lot of trust in scientific findings, one should not forget that sometimes even the greatest scientists can be wrong. What was once considered genuine scientific knowledge may currently be discarded. The scientific method places much emphasis on peer review and falsification. This process aims to improve the veracity of scientific claims. We should be wary when scientists refuse their hypothesis to be tested by peers. This may indicate that they have something to hide, such as unethical or erroneous methodology, data manipulation or  unfounded claims.  Some scientists have even become guilty of scams and hoaxes such as the Piltdown hoax. The drive to come up with ground breaking scientific discoveries has led some researchers to tamper with data and evidence. The more recent case of Andrew Wakefield and the MMR vaccine highlights the importance of peer review and the questioning of expert opinion in the field of the natural sciences. To verify scientific knowledge, we should ideally be able to repeat experiments. However, some great scientific hypotheses cannot be tested through experiments with observable data. Our sense perception is not perfect, despite the enormous advancements in technology. It is also practically impossible to repeat experiments infinitely. In that sense, Popper proposed that scientists try to falsify (prove wrong) each others' ideas and findings. For example, if a scientist claims that metals expand when heated, other scientists are invited to actively prove that this is not true. They should look for situations in which metals do not expand when heated, for example. This process of falsification aims to ensure the validity of scientific knowledge. It also leads to the improvement of some scientific knowledge, as theories can be refined, for example. Generally, we do not accept scientific knowledge that is not supported by a wider scientific community. Sometimes individuals can be right, but over time, the wider community usually catches on. Peer review is very important. When one expert claims something is scientifically true, his/her peers will review the validity of the claims. This can happen through verification or falsification. Within the scientific community, we do not accept a claim by an expert simply because s/he is an expert. Someone's word is simply not enough. Nevertheless, falsification as well as verification are limited. This is partly due to problems with induction, reasoning and observation, which all play an important role within the scientific method.
As our scientific knowledge advances, we may have to revise previous ideas. Our understanding of atoms and human DNA has evolved considerably over the last century, new elements have recently been added to the periodic table, and the list goes on and on. Our knowledge sometimes expands and we can fill in the gaps of the knowledge maps (for example when the previously predicted elements of the periodic table have been discovered). Sometimes, we have to rewrite the knowledge maps because previous maps were inaccurate. For example, phrenology or the theory of harmony have been removed from our scientific knowledge map. In this sense, scientific knowledge arguably improves over time. It becomes better, more accurate and more expansive.
This progress is not necessarily gradual. It can happen in shocks and waves. Sometimes we have to revise our entire way of scientific thinking and a paradigm shift occurs, as described by Thomas Kuhn.
When competing theories co-exist at one point in time, it is not always easy to decide which one should survive. We could use some general guidelines, however.  A theory that explains most data and a theory that can predict what was not observed yet before is often a good theory. For example, Mendeleev had predicted the existence of several undiscovered elements. A theory that is not backed up with much evidence from experiments and data is not usually regarded as very scientific. Theories like climate change and the theory of evolution seem to have withstood the test of time and are generally accepted today. We can find many historical examples of where the scientific world had actually accepted the wrong theory (e.g. the geocentric model). It seems that scientific progress can be made possible by the continual testing and falsification of theories. This is what makes science different from a dogma. Interestingly, some incorrect theories have their value as they sometimes give rise to the creation of new theories and scientific discoveries. Not all current scientific theories will be accepted in the future and it is perhaps a good thing that experts often disagree within a scientific disciple. The scientific community has an obligation to analyse the acceptability of scientific knowledge claims and theories,\ through peer review and falsification. The wider community should check under what circumstances we should or shouldn't accept expert opinion and not blindly accept catchy headlines of the popular press.

Theory and law

Progress...  but at what price?

Should scientific research be subject to ethical constraints,
​or is the pursuit of all scientific knowledge intrinsically worthwhile?

​Western civilisation went through a major cognitive paradigm shift around the 17th Century. Discoveries by Galileo and Newton challenged the prevalent dominant discourse. A new theory of knowledge primarily based on empirical evidence and reason was created. Scientific evidence soon became synonymous with 'ultimate proof' and religious knowledge was challenged by scientific sceptics. This scientific revolution brought about major changes in the way we thought about the world, particularly in the West. Mankind arguably benefited in many ways from this cognitive paradigm shift and with an increased understanding of the world around us, living standards and perhaps even our education generally improved.
Others question the impact of natural sciences exactly from the perspective of other areas of knowledge such as ethics. The possession of scientific knowledge undoubtedly entails ethical responsibility. How far can and should we go in our search for scientific knowledge? What kinds of experiments should we (not) conduct and why? On what basis can we decide that something is called progress? On what basis can we decide it is OK to "redesign nature"?
Some people also question the human limitations in the search for scientific knowledge. We are bound to our human frame in our understanding of the world. Can we trust our human ways of knowing? What can we do to enhance the power of these human tools? ​​

Lesson idea: Ethical "Carte Blanche"
On Ethics and The Natural Sciences​What if...? 

What if natural scientists had an ethical "carte blanche"? 
What kind of things would we (want to) research?
​What might we know?
What might be the possible consequences of scientific knowledge acquired through such means?

• Brainstorm the above questions in groups on large sheets of paper/write on tables. 
• For each possible consequence of your "ethical carte blanche", think of other subsequent consequences (be creative!)
• Walk around the tables and compare your group's findings with those of others.

Follow-up discussion:

What criteria could we use to decide whether the pursuit and/or possession of scientific knowledge is ethical?

Reflection: Has the concept "natural sciences" always meant the same thing throughout history?

Scope: A scientific theory of everything? 

With the rapid advancement of knowledge produced by the sciences over the last centuries, people started to explore the boundaries of the latter's scope. Some feel that because of science's successes, virtually everything can and should be explained through the natural sciences. In that respect, science can become a kind of religion, the basic explanation of our human condition and an answer to our moral questions.  But are the successes in the field of the natural sciences sufficient to discard knowledge constructed within other areas of knowledge? Not really, the natural sciences do not offer much guidance in terms of how we ought to live our lives, for example. The natural sciences can explain things in its own neutral language, but there are situations in which this would not be the most appropriate. For example, when a friend of yours gets cancer and you want to have a conversation about his/her feelings. Scientific language is more neutral or distant than the language we use in every day conversation. When your doctor explains the disease in scientific terminology (neoplasms, carcinoma, lymphoma, etc), the knowledge he passes on is correct. But if you want to tap into the emotional core of what the disease is about, this kind of explanation is perhaps quite useless. In that sense, Stromae's artistic interpretation is much more suitable and powerful. When we define love in scientific terms, we may ignore nuances which artists can grasp, for example. Reducing love to the effects of chemicals. is perhaps a little bit sad. I would truly hope that the love I feel for my children and my husband is not merely a matter of chemicals or "a love potion", as we might call it. Reducing depression to mere biological factors may not be very good at explaining the full extent of this human behaviour. Our human nature is only partly biological. So are we suitable objects for (natural) scientific study? Can we fully explain how our body works in scientific terms? Is illness purely biological? What about mental illness? Where do natural sciences stop and human sciences begin? Human beings are difficult and complex objects of study.
It is important to remember that despite the obvious strengths of the natural sciences as an area in which we create knowledge, the natural sciences may not answer all of life's questions. Are we at risk of reducing the world through our love for the natural science? Is there room for a a holistic approach towards knowledge in a world so heavily influenced by the (largely compartmentalised) scientific method? Or does science have the ability to give us knowledge about more than just the natural world: our origins, what is right or wrong, or even God?

Making connections to the core theme, as suggested by the TOK Guide

• How might members of the public judge whether to accept scientific findings if they do not have detailed scientific knowledge? 
• How is it that scientific knowledge is often shared by large, geographically spread and culturally diverse groups?
• How do scientists make use of, or work around, their intuitions?

Possible knowledge questions on the Natural Sciences

Acknowledgements: These knowledge questions are taken from the TOK Guide, 2022 specification

What is the study of the natural world?

What are diverse ways that scientists study the natural world and propose explanations based on evidence?

How do scientists gather information about the natural world?

What are the methods of natural science?