Inductive and Deductive Reasoning

steps to the theory of genetic inheritance

1. Theory 2. Hypothesis 3. Observation 4. Confirmation

Steps of Inductive Reasoning

1. observation 2. pattern 3. tentative hypothesis 4. theory

example of deductive reasoning

Democrats are elitists, environmental tree huggers, anti-war activists, big government advocates, pro-abortion, pro-gay and illegal immigrant protectors (generalization). Uncle Steve will run for office for the Democrats next year (a specific person). He must be an elitists, environmental tree hugger, anti-war activist, big government advocate, pro abortion, pro-gay and illegal immigrant protector (conclusion used the general premise to describe a specific person, Uncle Steve).

Theory of Genetic Inheritance

Developed by Gregory Mendel. a theory that suggested ways by which genes reproduce in organisms from one generation to the next (general statement). His work studying and breeding multiple generations of pea plants provided opportunities to collect data and observations (specific plant). He concluded that his theory was correct when his observations matched his theory.

example of inductive reasoning

It snowed in Massachusetts in December 2011, 2010, 2009, 2008, 2007, etc. (observations about specific years). Therefore it will snow in Massachusetts in 2013 and 2014 (generalization based on previous yearly observation).

example of inductive reasoning

Jack and John are guitarists and they feel pain in their fingers after playing 2 hours straight (specific people). Therefore, all guitarists feel pain in their fingers after playing 2 hours straight ((generalization based on Jack and John's finger pain).

example of inductive reasoning

Look at how those few people are behaving at the Tea Party rally. A few of them have racist signs (observations about specific people). Therefore all Tea Partiers are racist (generalization based on observed individuals).

example of inductive reasoning

When exposed to the nerve argent known as "Rage", Zee the chimpanzee showed a massive increase in aggression (specific chimpanzee). Humans are very similar to chimpanzees, so when exposed to "Rage", humans would show a massive increase in aggression (generalization based on specific observation of aggression).

example of deductive reasoning

Women office workers work just as hard as men office workers, and are just as productive but women office workers receive less pay than men in comparable positions (generalization). Samantha works as an office (specific person). I conclude that her salary is less than a co-worker in a similar position.

example of deductive reasoning

all planets orbit the sun (general statement). The earth is a planet (this is a specific case of a planet). Therefore the earth orbits the sun. (the conclusion uses the general premise to describe the motion of a specific planet, Earth).

Theory of Biological Evolution

created by Charles Darwin. Charles Darwin caught many finches on the Galapagos Islands. He noticed that the shapes of the birds' beaks he studied were different on each island. He concluded that each shape seemed to serve a purpose suited to the conditions on a particular island (specific observations). Darwin generalized that at some time in the past, one type of finch arrived at the islands and then evolved differently on each island. He later extended this generalization to all life forms with his Theory of Biological Evolution.

Inductive Reasoning

reasoning works the other way, moving from specific observations to broader generalizations and theories. Informally, we sometimes call this a "bottom up" approach. In inductive reasoning, we begin with specific observations and measures, begin to detect patterns and regularities, formulate some tentative hypotheses that we can explore, and finally end up developing some general conclusions or theories.

deductive reasoning

works from the more general to the more specific. Sometimes this is informally called a "top-down" approach. We might begin with thinking up a hypothesis or generalization about our topic of interest. We then narrow that down by collecting and studying specific observations to address whether they are consistent or not with the initial hypothesis or generalization. Deductive reasoning is narrow in nature and is concerned with testing or confirming hypotheses.