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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