Inductive Reasoning:
Jennifer leaves for school at 7:00 a.m. Jennifer is always on time. Jennifer assumes, then, that she will always be on time if she leaves at 7:00 a.m.
Every windstorm in this area comes from the north. I can see a big cloud of dust caused by a windstorm in the distance; so, a new windstorm is coming from the north.
Bob is showing a big diamond ring to his friend Larry. Bob has told Larry that he is going to marry Joan. Bob has bought the diamond ring to give to Joan.
The chair in the living room is red. The chair in the dining room is red. The chair in the bedrrom is red. All chairs in the house are red.
Every time you eat peanuts, your throat sweels up and you can't breath. So, you are allergic to peanuts.
Two-thirds of the students at this college receive student aid. Therefore, two-thirds of all college students receive student aid.
Michael just moved here from Chicago. Michael has red hair, therefore people from Chicago have red hair.
John is an excellent swimmer. John's family has a swimming pool. John's sister Mary must also be an excellent swimmer.
All children in the day care center like to play with Legos. All children, therefore, enjoy playing with Legos.
Ray is a football person. All football persons weigh more than 170 pounds. Ray weighs more than 170 pounds.
All observed houses on the South Street are falling apart. Sherry lives on South Street. Her house is falling apart.
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~All observed small people are right-handed, therefore all right-handed are small people and all small people are right-handed.
John and Joe are friends. John likes to sing, write and read. Joe likes to sing and write. Therefore one assumes that Joe also likes to read.
~Every time John eats shrimp, he gets cramps, and therefore he assumes that he gets cramps because he eats shrimp.
~John is an amazing athlete. So John's son too will go on to become an amazing athlete.
~When chimpanzees are exposed to rage, they tend to become violent. Humans are similar to chimpanzees, and therefore they tend to get violent when exposed to rage.
~The woman in the neighboring apartment has a shrill voice. I can hear a shrill voice from outside. There is a high probability that the woman in the neighboring apartment is shouting.
~All the dogs which were subjected to routine diagnosis had fleas, so one concludes that all the dogs have fleas.
~The Philadelphia Falcons have won their last four matches in a one-sided contest, and therefore their fans conclude that the Falcons will win their fifth match as well.
~Every time you get a call from some unknown number, you find a telemarketer on the other side of the line. It makes you conclude that if it's an unknown call, it is most likely to be a telemarketer.
~You see a dog chasing a cat in your neighborhood a couple of times, and start believing that the two animals cannot be kept in one house.
~A few episodes of a particular sitcom make you laugh, and you conclude that the said sitcom is very funny.
~100 pens are kept in front of you. On checking the first 10 pens, you note that 5 had black ink and 5 had blue ink, and therefore you conclude that half of the 100 pens are black and half are blue.
Deductive Reasoning :
In mathematics, If A = B and B = C, then A = C.
Since all humans are mortal, and I am a human, then I am mortal.
All dolphins are mammals, all mammals have kidneys; therefore all dolphins have kidneys.
Since all squares are rectangles, and all rectangles have four sides, so all squares have four sides.
If Dennis misses work and at work there is a party, then Dennis will miss the party.
All numbers ending in 0 or 5 are divisible by 5. The number 35 ends with a 5, so it is divisible by 5.
To earn a master's degree, a student must have 32 credits. Tim has 40 credits, so Tim will earn a master's degree.
All birds have feathers and robins are birds, so robins have feathers.
It is dangerous to drive on icy streets. The streets are icy now so it is dangerous to drive now.
All cats have a keen sense of smell. Fluffy is a cat, so Fluffy has a keen sense of smell.
Snakes are reptiles and reptiles are cold-blooded; therefore, snakes are cold-blooded.
Cacti are plants and all plants perform photosynthesis; therefore, cacti perform photosynthesis.
Red meat has iron in it and beef is red meat, so beef has iron in it.
Acute angles are less than 90 degrees and this angle is 40 degrees so this angle is acute.
All noble gases are stable and helium is a noble gas, so helium is stable.
Magnolias are dicots and dicots have two embryonic leaves; therefore magnolias have two embryonic leaves.
Elephants have cells in their bodies and all cells have DNA, so elephants have DNA.
All cars have at least two doors and a Ford Focus is a car, so the Ford Focus has at least two doors.
All horses have manes and the Arabian is a horse; therefore Arabians have manes.
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Other Patterns of Deductive Reasoning:
Some deductive reasoning does not follow the classic reasoning pattern of A = B and B = C, then A = C. Some examples of other patterns are:
Be careful around bees, they might sting you. (The reasoning is understood that all bees might sting.)
It takes me an hour to get to the mall. If I leave at five o'clock I will reach the mall by six o'clock.
That dog is growling so be careful or you might get bitten. (It is logical is the dog is angry, he might bite.)
The apple hit me on the head because of gravity.
There are three people in my family. Each one is tall, so everyone in my family is tall.
