Questions for Today1. What is the Nature of Science?2. What are the differences between a theory and

a law?3. What are the differences between inductive and

deductive reasoning?4. What are the two categories that Scientific

Results fall into?5. What are the limitations of Environmental

Science?

What is the Nature of Science?• Science is an attempt to discover order in

the natural world and to use that knowledge to make predictions about what is likely to happen in nature.

What is the Nature of Science?• There are no set steps in understanding nature.

Scientists often follow a method in developing scientific explanations, though not in not always in the order listed:– Ask a Question or identify a problem.– Collect data by making observations and measurements.– Develop a hypothesis– Make Predictions– Test Predictions– Accept or reject the hypothesis

• The purpose of Science is to explain natural phenomena with scientific theories.

Differences between Theory and Law.• A widely tested and accepted scientific

hypothesis becomes a scientific theory.– Before becoming a theory, the data from the

hypothesis must pass peer review, skepticism, and must be reproducible.

– Examples of Scientific Theories are Evolution, the Atomic Theory, and Schrödinger’s Cat.

Schrödinger’s Cat

Differences between Theory and Law.• A scientific law describes what we find

happening in nature over and over again.– Examples of Scientific Law are the Laws of

Thermodynamics, Law of Gravity, and Newton’s Laws.

Inductive vs. Deductive Reasoning• Scientists use inductive reasoning to

convert observations and measurements to a general conclusion and deductive reasoning to convert a generalization to a specific conclusion.

Inductive vs. Deductive Reasoning• Inductive reasoning uses specific observations and

measurements to derive a hypothesis or conclusions– “Bottom-up” reasoning– From the very specific to the general– Experimental Scientists

• Deductive reasoning uses logic to arrive at a specific conclusion based on a generalization or premise.– “Top-down” reasoning– From generalizations to a specific conclusion– Sherlock Holmes

Inductive Riddle• You have two fuses of equal length and are

made from the same material.• You know that the fuse burns for one hour,

but burns for different rates.• How would you measure 45 minutes?

Deductive Riddle• Somewhat ate the butcher’s

sausages!• Here are what the four boys at

the scene of the crime said:– A: “B ate the sausages!”– B: “D ate the sausages!”– C: “I didn’t eat them, no way!”– D: “B is totally lying!”

• Only one of these boys are telling the truth, and all the others are lying. Who is telling the truth and who ate the sausages?

What are the two categories that scientific results fall into?• Scientific results fall into two categories:

those that have not been confirmed (frontier science) and those that have been well tested and widely accepted (sound or reliable science).

What are the two categories that scientific results fall into?• Frontier science is results that are often

controversial because they have not been widely tested and accepted by peer review.

What are the two categories that scientific results fall into?• Sound science, also called consensus science,

consists of data, theories, and laws that are widely accepted by scientists who are considered experts in the field.– Check the U.S. National Academy of Sciences and the

British Royal Society.– Junk (unreliable) Science are scientific results or

theories that are presented as sound science, but have not undergone rigorous peer review or have already been discredited by peer review.

What are the limitations of Environmental Sciences?• Scientists can disprove things but cannot prove

anything absolutely because there is always some degree of uncertainty in scientific findings.

– Scientists try to establish high probability (90-99%) in their findings.

– I.E. Scientists rarely say that “Cigarettes cause lung cancer,” they might say, “Overwhelming evidence from thousands of studies indicates that there is a significant relationship between cigarette smoking and lung cancer.”

• Scientists are human and cannot be expected to be totally free of bias about their results.

– $$$$$$

What are the limitations of Environmental Sciences?• Another limitation in Environmental Science is

the validity of the data. – No way to measure some of the statistics due to size

and time– Use Statistical Samples and Models– They predict trends

• Most environmental problems are difficult to understand because they involve many variables and highly complex interactions.

– What are the different factors that lead to the depletion of species?