Create-Test-Use Examples

Create-Test-Use Examples

Evidence obtained from valid and reliable scientific investigations is the ultimate authority in science. The evidence not only provides all of the empirical knowledge but also is essential to test the predictions made from theories. In science, everything comes down to evidence. What kind of reasoning is involved to collect evidence through laboratory work? Most of the laboratory work up to the end of the twentieth century was predominately inductive in nature. A modern view of the nature of science has expanded this into four categories—inductive, testing hypotheses, testing predictions, and deductive logic/reasoning.

Table 2: Examples of Scientific Research and Types of Reasoning

Reasoning / Example
inductive (I) / Purpose
To create an organization of known chemical elements.
Problem
How can the chemical elements be arranged in a logical way based on their properties?
Design
Obtain all known empirical properties of elements. Order the elements based on similarities and differences.
inductive-hypothesis testing (H-I)
(hypothetico-inductive) / Purpose
To test the hypothesis that the traits of the offspring are obtained from the parents.
Problem
How are traits passed on from parent to offspring?
Hypothesis
The traits of the parent are passed to subsequent generations without any blending of parent characteristics.
Design
Using the common pea plant, cross pollinate two plants with a different trait such as pea shape or colour, pod shape or colour, flower colour or position, and plant size. Observe the traits of the offspring. Self pollinate the offspring to produce several more generations, recording the traits in each generation.
deductive-prediction testing (H-D)
(hypothetico-deductive) / Purpose
To test the Thomson model of the atom.
Problem
What effect do the atoms have on a stream of alpha particles passed through a thin layer of gold atoms?
Prediction
According to the Thomson model, alpha particles should be deflected slightly or not at all.
Design
A stream of alpha particles from a radioactive source is aimed at a thin gold foil. The alpha particles that have passed through the foil are detected by a scintillation screen.
deductive (D) / Purpose
To use DNA to determine the number of grizzly bears in a specific population.
Problem
How many different grizzly bears exist in a particular area?
Design
A string of barbed wire is mounted to encircle several trees with some bait placed in the centre. When a bear passes under the barbed wire a small tuft of hair is left behind. This hair is collected periodically and the DNA analyzed.

Also see the CTU series for Newton’s second law and for the stoichiometric law where the laws are created, tested and tested again before being used.

Exercise

1. In simplified terms, what is the difference between inductive and deductive reasoning?

Answer:

Inductive reasoning starts with specific descriptions in order to obtain some general conclusion. Deductive reasoning starts with some general statements to obtain some specific conclusions.

For questions 2 to 5, match the type of reasoning (A to D) with the given description.

A. inductive

B. inductive-hypothesis testing

C. deductive-prediction testing

D. deductive

2. John Dalton, best known as for his atomic theory, spent about fifty-seven years recording over two hundred thousand observations about the weather with the aim of discovering general patterns.

Answer: A

3. Starting only with some general ideas and beliefs about nature, Democritus deduced that all substances were made up of the smallest possible particles which he called atoms (from the Greek, meaning indivisible).

Answer: D

4. Pasteur had a hunch that some microorganisms were the cause of contamination of fermenting beverages. He showed through a series of experiments that if the starting liquid were heated to kill these organisms no contamination occurred. This process was eventually known as pasteurization.

Answer: B (Pasteur tested his hypothesis.)

5. According to the phlogiston theory, there is a fire-like element that is contained in combustible materials and released during combustion. Antoine Lavoisier falsified this theory by showing experimentally that combustion does not produce a fire-like element but does require oxygen.

Answer: C (assuming that the fire-like element is a prediction of the phlogiston theory)

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