Definition of HYPOTHESIS
Hypothesis has different interrelating meanings in different contexts, but no overarching simple definition that describes all of them exactly.
In Formal Logic and in Mathematics
The most primitive and original meaning of "hypothesis" appears to be simply whatever we're reasoning FROM in a logical argument. This belongs to a view of logic that says the purpose of logic is not so much to establish absolute truths, but to find out what follows from what else. Then whatever something follows from is the hypothesis of the argument that the "something" indeed follows.
In formal logic and mathematics “hypothesis is defined as: the antecedent clause of a conditional statement. Where antecedent is defined as: The conditional element in a proposition (as if A in “if A, then B”) and a conditional statement is an statement of the form “if A, then B”.
Example: If a number is divisible by 10, then it is divisible by 2 is a conditional statement whose hypothesis is if a number is divisible by 10 and whose conclusion is then it is divisible by 2.
Quite commonly in mathematics we use the so-called “If-Then” statements.
1. If two odd natural numbers are added, then the sum is an even natural number.
2. If the same expression is added to both sides of an equation, then the new equation is equivalent to the original equation.
3. If the product of two real numbers is zero, then at least one of the factors is zero.
4. If a and b represent real numbers, then exactly one of the following is true:
· a < b
· a = b
· a > b
In each of these statements, the “if clause” is the hypothesis and the “then clause” is the conclusion.
As a technical term within logic, the meaning of "hypothesis" is exactly synonymous with "assumption".
It is important to observe, and remain aware of the fact that no assertion is made about the truth value of the hypothesis. Only that IF the hypothesis is true, then the conclusion must be true.
Consider the following statement:
If my children were born after 2000, then they are less than 20 years old.
That statement DOES NOT imply that my children are less than 20 years old. However, the statement is True.
In The Scientific Method
The steps of the scientific method are nicely diagramed at: http://www.sciencebuddies.org/science-fair-projects/project_scientific_method.shtml?gclid=CMC4uLX-48QCFc3m7AodRGwAWQ#overviewofthescientificmethod
and is displayed here.
In this context:
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous observations that cannot satisfactorily be explained with the available scientific theories. Even though the words "hypothesis" and "theory" are often used synonymously, a scientific hypothesis is not the same as a scientific theory. A working hypothesis is a provisionally accepted hypothesis proposed for further research.[1]
A hypothesis is a suggestedsolutionfor an unexplained occurrence that does not fit into current acceptedscientific theory. The basic idea of a hypothesis is that there is no pre-determined outcome. For a hypothesis to be termed a scientific hypothesis, it has to be something that can be supported or refuted through carefully crafted experimentation or observation. This is called falsifiability and testability, according to the Encyclopedia Britannica.
A key function in this step in the scientific method is deriving predictions from the hypotheses about the results of future experiments, and then performingthose experiments to see whether they support the predictions.
A hypothesis is usually written in the form of an if/then statement, according to theUniversity of California. This statement gives a possibility (if) and explains what may happen because of the possibility (then). For example, if garlic repels fleas, then a dog is given garlic every day will not get fleas.
**Usually, a hypothesis can be supported or refuted through experimentation or more observation. A hypothesis can be disproven, but not proven to be true.
Example: If you see no difference in the cleaning ability of various laundry detergents, you might hypothesize that cleaning effectiveness is not affected by which detergent you use. You can see this hypothesis can be disproven if a stain is removed by one detergent and not another. On the other hand, you cannot prove the hypothesis. Even if you never see a difference in the cleanliness of your clothes after trying a thousand detergents, there might be one you haven't tried that could be different.
Examples:
If I raise the temperature of a cup of water, then the amount of sugar that can be dissolved in it will be increased.
If fenders are placed on a bicycle, then the user will stay dry when going through puddles.
In the world of statistics and science, most hypotheses are written as "if...then" statements. For example someone performing experiments on plant growth might report this hypothesis: "If I give a plant an unlimited amount of sunlight, then the plant will grow to its largest possible size." Hypotheses cannot be proven correct from the data obtained in the experiment, instead hypotheses are either supported by the data collected or refuted by the data collected.
1. If I replace the battery in my car, then my car will get better gas mileage.
2. If I eat more vegetables, then I will lose weight faster.
3. If I add fertilizer to my garden, then my plants will grow faster.
4. If I brush my teeth every day, then I will not develop cavities.
5. If I take my vitamins every day, then I will not feel tired.
6. If 50 mL of water are added to my plants each day and they grow, then adding 100 mL of water each day will make them grow even more.
Writing Hypothesis (The following was written by Rick Miranda of the Biology Dept at California State University, Bakersfield CSUB http://www.csub.edu/~emiranda3/Writing%20Hypotheses.doc)
Purpose: To learn when and how to write hypotheses.
Most students believe that they are going to be experimenting anytime they are given a laboratory assignment in science. However, more often than not, students are doing something other than experiments. This is not necessarily bad. A good deal of science is observational and descriptive. For example, the study of bio-diversity usually involves looking at wide variety of specimens and maybe sketching and recording their unique characteristics. However, there are other times when we science teachers are trying to teach students how scientists work and how we can verify things which others may say or believe is so without any proof.
To learn about what is not known or to verify a notion, the so-called "scientific method" might be carried out and an actual experiment may be conducted. It does not matter that your experiment has been done a thousand times before or that your teacher already knows the results. What matters is that you don't know the results and that you can independently find a verifiable answer. In real experiments, real hypotheses should be written before the actual experiment.
What Is a Real Hypothesis?
A hypothesis is a tentative statement that proposes a possible explanation to some phenomenon or event. A useful hypothesis is a testable statement which may include a prediction. A hypotheses should not be confused with a theory. Theories are general explanations based on a large amount of data. For example, the theory of evolution applies to all living things and is based on wide range of observations. However, there are many things about evolution that are not fully understood such as gaps in the fossil record. Many hypotheses have been proposed and tested.
When Are Hypotheses Used?
The key word is testable. That is, you will perform a test of how two variables might be related. This is when you are doing a real experiment. You are testing variables. Usually, a hypothesis is based on some previous observation such as noticing that in November many trees undergo color changes in their leaves and the average daily temperatures are dropping. Are these two events connected? How?
Any laboratory procedure you follow without a hypothesis is really not an experiment. It is just an exercise or demonstration of what is already known.
How Are Hypotheses Written?
1. Chocolate may cause pimples.
2. Salt in soil may affect plant growth.
3. Plant growth may be affected by the color of the light.
4. Bacterial growth may be affected by temperature.
5. Ultra violet light may cause skin cancer.
6. Temperature may cause leaves to change color.
All of these are examples of hypotheses because they use the tentative word "may." However, their form is not particularly useful. Using the word may does not suggest how you would go about proving it. If these statements had not been written carefully, they may not have even been hypotheses at all. For example, if we say "Trees will change color when it gets cold." we are making a prediction. Or if we write, "Ultraviolet light causes skin cancer." could be a conclusion. One way to prevent making such easy mistakes is to formalize the form of the hypothesis.
Formalized Hypotheses example: If skin cancer is related to ultraviolet light , then people with a high exposure to uv light will have a higher frequency of skin cancer.
If leaf color change is related to temperature , then exposing plants to low temperatures will result in changes in leaf color.
Notice that these statements contain the words , if and then. They are necessary in a formalized hypothesis. But not all if-then statements are hypotheses. For example, "If I play the lottery, then I will get rich." This is a simple prediction. In a formalized hypothesis, a tentative relationship is stated. For example, if the frequency of winning is related to frequency of buying lottery tickets. "Then" is followed by a prediction of what will happen if you increase or decrease the frequency of buying lottery tickets. If you always ask yourself that if one thing is related to another, then you should be able to test it.
Formalized hypotheses contain two variables. One is "independent" and the other is "dependent." The independent variable is the one you, the "scientist" control and the dependent variable is the one that you observe and/or measure the results. In the statements above the dependent variable is blue and the independent variable is red.
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