How Science Is done the light switch is turned off. An alternative hypothes might be, "There is no light in the room because the light How do scientists establish which general principles are bulb is burned out. " And yet another alternative hypothe true from among the many that might be true? They do sis might be, "I am going blind. "To evaluate these hy this by systematically testing alternative proposals. If these potheses, you would conduct an experiment designed to proposals prove inconsistent with experimental observa- eliminate one or more of the hypotheses. For example, you tions, they are rejected as untrue. After making careful ob- might test your hypotheses by reversing the position of the servations concerning a particular area of science, scien ight switch. If you do so and the light does not come on, tists construct a hypothesis, which is a suggested you have disproved the first hypothesis. Something other explanation that accounts for those observations. A hy- than the setting of the light switch must be the reason for pothesis is a proposition that might be true. Those hy he darkness. Note that a test such as this does not prove potheses that have not yet been disproved are retained. that any of the other hypotheses are true; it merely dem- They are useful because they fit the known facts, but they onstrates that one of them is not. A successful experiment are always subject to future rejection if, in the light of new is one in which one or more of the alternative hypotheses information they are found to be incorrect. is demonstrated to be inconsistent with the results and is Testing Hypotheses As you proceed through this text, you will encounter many hypotheses that have withstood the test of experiment We call the test of a hypothesis an experiment(figure Many will continue to do so; others will be revised as new 1. 4). Suppose that a room appears dark to you. To under- observations are made by biologists. Biology, like all science, stand why it appears dark, you propose several hypotheses. is in a constant state of change, with new ideas appearing The first might be, "There is no light in the room because and replacing old ones Question Hypothesis 1 Hypothesis 2 hypotheses Hypothesis 5 1 and 4 HHH Experiment 2 and 3 FIGURE 1.4 How science is done. This diagram il- Remaining lustrates the way in which scientific in- hypotheses vestigations proceed. First, scientists make observations that raise a particular question. They develop a number of potential explanations Predictions (hypotheses)to answer the question Next, they carry out experiments in ar attempt to eliminate one or more of these hypotheses. Then, predictions are Experiment 1)(Experiment 2 made based on the remaining hypotheses, and further experiments are carried out to test these predictions. As a result of this process, the least confirmed unlikely hypothesis is selected Chapter 1 The Science of Biology 7How Science Is Done How do scientists establish which general principles are true from among the many that might be true? They do this by systematically testing alternative proposals. If these proposals prove inconsistent with experimental observa￾tions, they are rejected as untrue. After making careful ob￾servations concerning a particular area of science, scien￾tists construct a hypothesis, which is a suggested explanation that accounts for those observations. A hy￾pothesis is a proposition that might be true. Those hy￾potheses that have not yet been disproved are retained. They are useful because they fit the known facts, but they are always subject to future rejection if, in the light of new information, they are found to be incorrect. Testing Hypotheses We call the test of a hypothesis an experiment (figure 1.4). Suppose that a room appears dark to you. To under￾stand why it appears dark, you propose several hypotheses. The first might be, “There is no light in the room because the light switch is turned off.” An alternative hypothesis might be, “There is no light in the room because the light￾bulb is burned out.” And yet another alternative hypothe￾sis might be, “I am going blind.” To evaluate these hy￾potheses, you would conduct an experiment designed to eliminate one or more of the hypotheses. For example, you might test your hypotheses by reversing the position of the light switch. If you do so and the light does not come on, you have disproved the first hypothesis. Something other than the setting of the light switch must be the reason for the darkness. Note that a test such as this does not prove that any of the other hypotheses are true; it merely dem￾onstrates that one of them is not. A successful experiment is one in which one or more of the alternative hypotheses is demonstrated to be inconsistent with the results and is thus rejected. As you proceed through this text, you will encounter many hypotheses that have withstood the test of experiment. Many will continue to do so; others will be revised as new observations are made by biologists. Biology, like all science, is in a constant state of change, with new ideas appearing and replacing old ones. Chapter 1 The Science of Biology 7 FIGURE 1.4 How science is done. This diagram il￾lustrates the way in which scientific in￾vestigations proceed. First, scientists make observations that raise a particular question. They develop a number of potential explanations (hypotheses) to answer the question. Next, they carry out experiments in an attempt to eliminate one or more of these hypotheses. Then, predictions are made based on the remaining hypotheses, and further experiments are carried out to test these predictions. As a result of this process, the least unlikely hypothesis is selected. Observation Question Experiment Hypothesis 1 Hypothesis 2 Hypothesis 3 Hypothesis 4 Hypothesis 5 Potential hypotheses Remaining possible hypotheses Last remaining possible hypothesis Reject hypotheses 1 and 4 Reject hypotheses 2 and 3 Experiment Experiment 1 Hypothesis 2 Hypothesis 3 Hypothesis 5 Hypothesis 5 Predictions Predictions confirmed Experiment 1 Experiment 2 Experiment 3 Experiment 4