π§ͺ What Is a Hypothesis?
β Definition:
A hypothesis is an educated guess or testable explanation for a scientific problem or observation.
It answers the question:
“What do I think is happening, and why?”
It must be:
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Testable (you can design an experiment to check it)
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Falsifiable (it can be proven wrong)
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Based on prior knowledge or observation
π Example:
If plants receive more sunlight, then they will grow faster.
π This is a hypothesis because it predicts something measurable and testable.
π Origin of the Word “Hypothesis”
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Comes from Greek:
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“hypo” = under
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“thesis” = placing or proposition
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So hypothesis originally meant: “a proposed idea placed under investigation”
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First used in Greek philosophy by Plato and Aristotle when discussing logic and reasoning.
π Historical Development
ποΈ Ancient Greece:
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Aristotle (384–322 BCE):
Talked about using observation and reasoning, but he did not use experiments the way modern science does. -
Euclid (geometry): Used hypotheses as starting points (axioms) for logical conclusions.
βοΈ Scientific Revolution (1500–1700s):
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Francis Bacon: Promoted the idea of inductive reasoning (start with observations to form general hypotheses).
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Galileo and Newton: Used hypotheses in forming laws of motion and gravity — but also emphasized testing with experiments.
π§ͺ Modern Science (1800–present):
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Karl Popper (20th century):
Said a good hypothesis must be falsifiable — it must be able to be tested and potentially disproven.
π¬ Hypothesis in the Scientific Method
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Observation: Notice something in the world.
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Question: Ask “Why or how is this happening?”
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Hypothesis: Make a guess based on what you know.
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Experiment: Test your guess with data.
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Analysis: See if results support or reject your hypothesis.
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Conclusion: Decide if you were right — or make a new hypothesis.
π Important:
A hypothesis is not the final answer — it is a starting point in science.
π§ Types of Hypotheses
| Type | Description | Example |
|---|---|---|
| Null Hypothesis (Hβ) | No effect or relationship | "There is no difference in plant growth with or without sunlight." |
| Alternative Hypothesis (Hβ) | There is an effect or relationship | "Plants grow faster with more sunlight." |
| Directional Hypothesis | Predicts the direction of the effect | "If temperature increases, bacteria grow faster." |
| Non-directional Hypothesis | Predicts a difference, not its direction | "There is a difference in growth between A and B." |
π Why Hypotheses Matter in Science
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They help focus research.
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They allow scientists to make predictions.
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They make science systematic and logical.
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They are the foundation of experiments.
π Summary
| Feature | Explanation |
|---|---|
| Meaning | A testable explanation or prediction |
| Origin | Greek word meaning “under-proposition” |
| Used in | Scientific Method |
| Must be | Testable and falsifiable |
| Evolved by | Plato → Aristotle → Bacon → Newton → Popper |