One day you wake up and realize your clock radio did not turn on to get you out of bed. You are puzzled, so you decide to find out what happened. You list three possible explanations:
- There was a power failure and your radio cannot turn on.
- Your little sister turned it off as a joke.
- You did not set the alarm last night.
Upon investigation you find that the clock is on, so there is no power failure. Your little sister was spending the night with a friend and could not have turned the alarm off. You notice that the alarm is not set - your forgetfulness made you late. You have used the scientific method to find an answer to a question.
Scientific Problem Solving
Humans have always wondered about the world around them. One of the questions of interest was (and still is) what is this world made of? Chemistry has been defined in various ways as the study of matter. What matter consists of has been a source of debate over the centuries. One of the key areas for this debate in the Western world was Greek philosophy.
The basic approach of these philosophers to questions about the world was discussion and debate. There was no gathering of information to speak of, just talking. As a result, several ideas about matter were put forth, but never resolved. The first philosopher to carry out the gathering of data was Aristotle (384 - 322 B.C.). He recorded many observations on the weather, on plant and animal life and behavior, on physical motions, and a number of other topics. Aristotle could probably be considered the first "real" scientist since he made systematic observations of nature and tried to understand what he was seeing.
Inductive and Deductive Reasoning
Two approaches to logical thinking developed over the centuries. These two methods are inductive reasoning and deductive reasoning. Inductive reasoning involves getting a collection of specific examples and drawing a general conclusion from them. Deductive reasoning takes a general principle and then draws a specific conclusion from the general concept. Both are used in the development of scientific ideas.
- Inductive reasoning first involves the collection of data. If I add sodium metal to water, I will observe a very violent reaction. Every time I repeat the process, I see the same thing happening. I draw a general conclusion from these observations: the addition of sodium to water results in a violent reaction.
- In deductive reasoning, I make a specific prediction based on a general principle. One general principle is that acids turn blue litmus paper red. If I have a bottle of liquid labeled "acid", I expect the litmus paper to turn red when I immerse it in the liquid.
The Idea of the Experiment
Inductive reasoning is at the heart of what we call the "scientific method". In European culture, this approach was developed mainly by Francis Bacon (1561 - 1626), a British scholar. He advocated the use of inductive reasoning in every area of life, not just science. The scientific method as developed by Bacon and others involved several steps:
- Ask a question - identify the problem to be considered.
- Make observations - gather data that pertains to the question.
- Propose an explanation (a hypothesis) for the observations.
- Make new observations to test the hypothesis further.
Note that this should not be considered a "cookbook" for scientific research. Scientists do not sit down with their daily "to do" list and write down these steps. The steps may not necessarily be followed in order. But this does provide a general idea of how scientific research is usually done.
When a hypothesis is confirmed repeatedly, it eventually becomes a theory - a general principle that is offered to explain natural phenomena. Note a key word - explanation. The theory offers a description of why something happens. A law, on the other hand, is a statement that is always true, but does not explain why. The law of gravity says a rock will fall when dropped, but does not explain why (gravitational theory is very complex and incomplete at present). The kinetic molecular theory of gases, on the other hand, tells what happens when a gas is heated in a closed container (the pressure increases), but also explains why (the motions of the gas molecules are increased due to the change in temperature). Theories do not get "promoted" to laws because laws do not answer the "why" question.
- The early Greek philosophers spend their time talking about nature, but did little or no actual exploration or investigation.
- Inductive reasoning - developing a general conclusion from a collection of observations.
- Deductive reasoning - making a specific statement based on a general principle.
- Scientific method - a process of observation, developing a hypothesis, and testing that hypothesis.
Use the link below to answer the following questions:
- Deductive Reasoning vs. Inductive Reasoning at http://www.livescience.com/21569-ded...induction.html
1. Describe deductive reasoning.
2. Develop your own example of deductive reasoning.
3. What is a syllogism?
4. Describe inductive reasoning.
5. What is adductive reasoning?
CK-12 Foundation by Sharon Bewick, Richard Parsons, Therese Forsythe, Shonna Robinson, and Jean Dupon.