Critical Thinking in Environmental Science

• Scientific understanding of life and its environment is based on scientific method
• The Scientific Process is:
  • A way of knowing
  • Results in conclusions, generalizations and sometimes scientific laws
  • Allows us to explain a phenomenon and make predictions (based on knowledge at the present time)
• Continuous process
  • Sometimes a science undergoes a fundamental revolution in ideas
• Science begins with observation
• Deals only with statements that can be disproven
  • A statement can be deemed scientific if someone can state a method by which it could be disproved
  • A statement is considered nonscientific if no one can think of a test to falsify it
• Science is a process of discovery
  • Continuing process who's essence is change in ideas
  • Events in the natural world follow patterns that can be understood through careful observation and scientific analysis

Observations, Facts and Inferences

• Observations:
  • Made by any of the five sense (empirically) or instruments that measure beyond what we sense
• Inference
  • Generalization that arises from a set of observations
• Fact
  • Observation about a particular thing agreed upon by all

Hypothesis

• Type of statement used
  • What scientists seek to test and inference
  • Can be disproved
• If a hypothesis has not been disproved
  • It is still not proven true
  • Only found to be probably true
• Test the hypothesis that: A plant can only use so much light and no more - it becomes saturated by an abundance of light

Controlling Variables

• A valid scientific experiment keeps all variables constant, except the independent and dependent variables
• Controlled Experiment
  • An exact duplicate of an experiment is compared back to a standard or control
  • One variable is altered (independent variable)
  • This may cause a change in another variable in the experiment (dependent variable)
• Dependent Variable
  • Dependent on the independent variable, a variable being observed and measured during an experiment.
  • Plant growth Experiment: Height of Plant
• Independent Variable
  • A variable that is changed or controlled by the experimenter in order to observe its effects on the dependent variable
  • Plant growth Experiment: Sunlight
• Manipulated Variable
  • Another Term For the Independent variable, as it is the variable the experimenter manipulates
• Responding Variable
  • Another Term For the Dependent variable, as it is the variable that responds to the manipulated variables changes.

Data

• Quantitative
  • Numerical
  • EX: Diameter of Tree Trunk
  • EX: Mass in Grams of Plant
• Qualitative
  • Non Numerical
  • EX: Species of a tree
  • EX: Color of a lime

The Nature of Scientific Proof

• The Scientific reasoning combines both deductive and inductive reasoning
• Deductive reasoning
  • Involves reasoning from initial definitions and assumptions
  • Science requires both logical reasoning and correct premises

Deductive Reasoning

• If 1 = 2 (premise)
• and 2 = 3 (premise)
• then 1 = 3 (conclusion)
• Premises
  • A straight line is the shortest path between two points
  • The line from A to B is the shortest distance between points A and B
• Conclusion
  • Therefore, the line from A to B is a straight line
• Proof using deductive reasoning, does not require that the premises be true, only that the reasoning is foolproof

[!My Note] First of all I dont like the use of numbers instead of variables, but why not use the Socrates example

All men are mortal, Socrates is a man, therefore Socrates is mortal

Inductive Reasoning

• Generalizations based on a number of observations
• EX: Breeding male grebes have golden feathers
• True until we observe a male grebe that does not have golden feathers
• Proof of inductive reasoning is stated in terms of probability of occurrence

Models and Theory

• Model
  • A deliberately simplified construct of nature
• Types
  • Physical working model
  • Pictorial model
  • Set of math equations
  • Computer model