? What is Science? What does it mean to know something? How does science differ from other ways of knowing? Science is tested against observation (empiricism) Science aims to disprove Science doesn’t care what the answer is to a question

Occam’s Razor: When more than one explanation agrees with observation, the simpler explanation is usually right Albert Einstein - Make everything as simple as possible, but not simpler

Observation Observation is the process of gathering information about events or processes in a careful, orderly way. Scientists collect data and use data to form inferences Data are either Qualitative: Things measured by quality – eg. Color Quantitative: Things measured in numbers – eg. Length, width An inference is a logical interpretation based on prior knowledge or experience

Induction moves from the specific to the general. Ex: These 6 elephants are sick, therefore I think all elephants in this population are sick. Induction is used to generate hypotheses but never provides true knowledge. Inferences are inductive. Deduction moves from the general to the specific. Ex. I think all the elephants in this population are sick. I test as many as I can, I find some that are not sick. Therefore, I can conclude my hypothesis was wrong. Deductive reasoning is the only logically valid type. Therefore, science can only disprove.

Hypothesis Follows observation and research The hypothesis is a prediction based on inference from observation Hypotheses must be testable to be considered scientific

Experiment Experiments are designed to attempt to disprove hypotheses Remember – Science can only disprove things

The language of experiments Independent Variable – The thing you are interested and manipulate Dependent Variable – The thing you measure to determine if the IV matters -- The DV depends on the IV Control – A part of the experiment that is run without treatment to determine if observed changes would have occurred anyway Constants – Things that don’t change during an experiment

The language of experiments If you restate the hypothesis as an if then prediction, it can help you remember these terms IF I _____ the _______ then ________ will _______ If I _____ the ___IV__ then ___DV__ will __DV___ Ex: If change the temperature then plants will grow IV = temp DV = plant growth

Famous Biology Experiments Aristotle (384-322 B.C.) observed rats emerging from hay and rags in corner of barn and concluded that the rats (living) arose from the hay and rags (nonliving). He thought that flies could be produced by first killing a bull, then burying it with its horns protruding from the ground. Flies emerged from one of the horns sawed off several days after burial. Aristotle’s interpretation was that life may arise from the nonliving (theory of spontaneous generation).

Famous experiments discrediting theory of spontaneous generation late 1700s 1862 1668

Conclusion Experiments either reject hypotheses (prove them wrong) or fail to reject hypotheses Experiments never prove anything positively Experimental results are published Other scientists try to repeat or refine the experiment Science works as a self correcting system

Theory Those hypotheses that have been repeatedly tested and have not been rejected are treated with extra weight Once a system of hypotheses providing a grand explanation of phenomena reaches the point that it is almost assured it will never be rejected, we call it a theory In science the word “theory” means much more than how it is used in common language Famous theories include Gravity, Evolution, Relativity “just a theory” in science means we are as sure of it as we are gravity