"By doubting we come to inquiry; by inquiring we perceive the truth."
|Figure 1: Hypothetico-deductive reasoning|
There is a simple little mental exercise, known as deductive reasoning, that is quite useful for discovering new things about how the world works. Deductive reasoning works by discovering something new based on two or more facts you already know to be true. If A=B and B=C, then A=C. Deductive reasoning can be performed mentally without evidence from nature to support the argument. It works quite well for geometry and simple questions. People who spend 8+ hours a day and devout their lives and career to deductive reasoning are called philosophers.
Another, more powerful exercise, known as hypothetico-deductive reasoning, on the other hand, provides an extra step to support new knowledge. It is quite handy when you need to confirm or challenge a belief or claim. People who spend 8+ hours a day and devout their lives and careers to hypothetico-deductive reasoning are called scientists and engineers. There are a lot more scientists and engineers in the world then philosophers.
To make use of hypothetico-deductive reasoning, first start with a central claim and call it the hypothesis. This hypothesis is then used to develop a model or method to test it's validity. Usually this method is in the form of a controlled experiment, but not always (figure 1). Now in most situations, you generally don't start with the hypothesis. You usually need to do some background research to formulate a workable (testable) hypothesis, and now-a-days, convince people to fund your research (figure 2).
If you are a medical researcher and you want to find out if acupuncture induces fertility, you can do an experiment to test it (or to spare yourself the effort and money, you can read about other people who did this experiment already). These types of controlled experiments can be complicated and expensive, but they generally involve treating to groups of randomly selected patients, one with the treatment to be tested and one with a placebo, and comparing the results. They yield reliable, objective, and predictable results when done properly.
We don't always have the luxury of conducting controlled experiments, however, so we often have to rely on lesser methods. If we wanted to know if smoking causes cancer for example, we could not ethically experiment on people, since that would involve randomly subjecting a group of people to take up smoking, but we can use 'observational studies' instead. We can, for example, find a group of people who already smoke and compare their health and their eventual fate with non-smokers. If we notice that the smokers developing cancer at a higher rate than non-smokers, that would lead us to think that there is a relationship between smoking and cancer. We can not be absolutely sure, however, because there may be a unknown variable that causes cancer as well as drive people to take up smoking: stress, poverty, etc. We can often make up for the deficiency of a controlled experiment by observing other predictable phenomena that would help support the smoking/cancer connection: laboratory studies on animals or cell cultures, for example. Building support for a claim can and often comes from more then one experimental source. If we know the biochemical mechanism that explains the development of cancer cells from particles in smoke that would help too.
|Figure 3: Inductive Reasoning|
Inductive ReasoningSometimes we don't need to use an experiment in the conventional sense, but can merely rely on observations for certain ideas. We know that white light is a combination of all other colors of light because when white light is passed through a prism, it separates into all other colors of light on the way out, whereas light of one color goes through a prism without changing. Nevertheless, whether we use a controlled experiment or simple observation, we are engaged in a dialogue with nature. The application of using nature to confirm our idea, or hypothesis, is referred to as empirical evidence, or simply empiricism.
Empiricism plays an even more important role in another type of reasoning known as generalization or argument by analogy. When you generalize, you are actually engaged in a type of reasoning known as induction, or inductive reasoning (figure 3), that works very differently than the hypothetico-deductive method; in fact, quite the opposite. Whereas in hypothetico-deductive reasoning, you start with an idea and use nature to confirm your idea. In generalization, you start with something in nature, you assume it behaves similar to other things like it, then you classify it with those other similar things or ideas. You can also use generalization to make predictions about how things will behave if you know their classification. For example, if you find a new animal species that has hair and mammary glands, you can classify it as mammal. Since it's a mammal, you can predict that it will give birth to live young (if it's female) and is warm-blooded. Generalizing, however doesn't mean you will always be correct; just correct most of the time. We can, for example, generalize that mammals have teeth and birds have beaks, but if we find a duck-billed platypus, a strange Australian creature with a duck-like beak, you would be wrong to assume it's a bird. It's actually a mammal. Further investigations would reveal that it a mammal that retained many primitive features in it's evolutionary development.
SynthesisBiological classification is a perfect example of how generalization is liberally employed in the study of nature. We generalize about other areas of nature as well: chemicals and materials, diseases, stars and planets, subatomic particles, etc. Like the hypothetico-deductive method, it's also a central role in our understanding of nature. A generalization is kind of like a researched hypothesis. Both are used to build more knowledge from data.
|Figure 4: The Central Dogma of Science|
It is also quite convenient that the two methods are very similar. The steps are essentially identical, except we are basically going in opposite directions. In hypothetico-deductive reasoning, we use an idea to predict a behavior in nature. In generalizations, we observe behaviors in nature to generalize about an idea (many of types of creatures behave similar enough to create categories like mammals, birds, etc.). The flow of information is also cyclical in both cases. The results of a experiment creates more knowledge and the knowledge created by generalization allows us to predict the appearance and/or behavior of nature (figure 5).
|Figure 5: Stream-lined Central Dogma of Science|
What Lowly Artisans Taught Elite PhilosophersOne of the first persons, that we know about, that described and wrote about these ideas was the Greek philosopher Plato. He was one of the people who wrote about, explored and taught the systems of obtaining knowledge through philosophical methods, although he may have been summarizing the ideas of an earlier philosopher by the name of Paramedies. Episteme was an ancient Greek word that roughly translates to knowledge. Episteme, however, wasn't any kind of knowledge, but rather a specific type of reliable, accurate knowledge that comes from logical contemplation or logos. Another type of knowledge was what the Greeks called Gnosis. This type of knowledge came from experience or emotion; from 'the gut'. It's generally considered to be less reliable but not necessarily wrong. Note also that episteme can be wrong as well, as when your logic is faulty. Aristotle for example 'reasoned' that the earth was the center of the universe, a vacuum cannot exist, men were more intelligent then women, and Greeks were the smartest people in the world, among numerous other errors.
Although the Greek philosophers loved philosophy, they never really did completely understand the hypothetico-deductive method that was to be the basis of modern science. One of the major reason Aristotle and other Greek philosophers were often wrong is because they distrusted nature. Philosophical contemplation, for the Greeks, was a mental and spiritual activity. It connected humans with the perfect, quintessential, and spiritual elements of heaven; the imperfect world of nature corrupted this purification ritual. Luckily though, not everyone reasoned the 'proper' way. Plato and his mentor, Paramedies, advocated this extremest perspective of logic and reason, but most everyone else found it quite difficult to learn anything new if you could not look to nature.
Aristotle himself had a falling out with the Platonic orthodoxy by claiming some observation of nature was necessary. Another group of people who relayed heavily on nature for new knowledge was a thriving community of medical professionals, or people we now-a-days call doctors or physicians. Unlike modern-day physicians, physicians of the ancient world were not formally trained in medical schools. They were more like craftsmen, who got their training from apprenticeships. In fact, doctors in the ancient world were in the same social class of lowly artisans. But like modern-day doctors, they conducted extensive research while treating patients. From as early as writing was first invented, doctors were recording case studies and histories, listing diseases and ailments, and even using their reasoning skills to conduct research, long before Aristotle and Francis Bacon articulated the processes.
Sometime in the 2nd century BC after the establishment of the library at Alexandria, there were a group of physicians who were worried about the quality of research and a growing lack of experimental rigor in the medical sciences. The past few centuries had experience a flowering of ideas that accumulated into a body of knowledge known as the Hippocratic corpus, much of which, but not all, was written by the semi-legendary Hippocrates. This was a great thing for scientific progress, mind you, but sometimes admiration for greatness and great people morphs in to a sort of hero worship, where the heroes and their works are blindly followed as unquestionable authority. Platonic ideas about heavenly perfection were making their way in the medical sciences as well. A system had been taken shape in which health was viewed as balance of 'humors' and restoration of health was achieved by restoring the balance. Doctors began to relay less and less on physical and natural observation and more and more on the system and the word of authority.
The concerned group of physicians became known as the Empiric school, and pushed for more emphasis on things like effective treatment, observation, and basing treatment of those observation rather an abstract reasoning process or authorized sources. The physicians they opposed became known as the Dogmatic school. The word dogma was actually a Greek word that simply meant a doctrine or set of theories.
Some of ideas of Dogmatic school, like the philosophical reasoning process outlined by Plato and Aristotle, turned out to be quite useful, but it was the Empiric school that provided the final step: experience, or communication with nature.
Some time in the 11th century, an engineer in Cairo, Egypt by the name of Ibn al-Haytham or better known as Alhazen, who studied a lot of Greek philosophy, articulated and expanded on these methods and brought them down to earth by applying them to nature. Like the Empirics, he was particularly interested in practical application and natural phenomena . He wrote about experimental and scientific methods in a book on light and optics. When the Europeans started to emerge from the 'Dark Ages' a few centuries later, they discovered Alhazen's works, along with other ancient and Muslim scholars, and used them to change the world.
- God, Science and the Joy of Pattern Recognition (or Parmenides vs. the Naturalists)
- The Triumph of Naturalism and the Legacy of the Weeping Philosopher
- Greek Colonies in Italy, Early Healthcare, and Guinea Worms
- A Brief History of Hunting: from Wild Animals to Subatomic Particles
Understanding Science: How Science Really Works - University of California Museum of Paleontology
Evaluating Scientific Claims (or, do we have to take a scientist's word for it) - Janet Stemwedel, Scientific American Blogs
How rationality can make your life more awesome -Julia Galef; Rationality Speaking blog
Bstan-'dzin-rgya-mtsho. 2005. The Universe in a Single Atom: the Convergence of Science and Spirituality. Morgan Road Books.
Richard Dawkins. 2011. The Magic of Reality: How We Know What's Really True. Transworld Publishers Limited.
Susan Haack. 2005. Defending Science—Within Reason: Between Science and Cynicism. Prometheus Books.
Bradley Steffens. 2007. Ibn Al-Haytham: the First Scientist.
Edward Theodore Withington. 1894. Medical History from the Earliest Times: a Popular History of the Healing Arts. London: The Scientific Press limited.