Inductive/ Deductive
Different arguments have different types of reasoning. Some arguments can be said to have inductive reasoning and some can be said to have deductive reasoning.
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Inductive arguments are based on experience/evidence and attempt to reach a conclusion by generalising from this evidence. Deductive arguments derive their conclusion through reason rather than evidence.
Can you see the differences in the examples below?
Inductive
P1 - Felix has a tail.
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P2 - Felix is a cat.
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C - Therefore, all cats have tails.
Deductive
P1 - All cats have tails.
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P2 - Felix is a cat.
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C - Therefore, Felix has a tail.
Deductive arguments usually begin with a very general premise and then go on to deduce the truth of some particular fact based on the general claim.
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Notice how the second argument above starts by talking about all cats and then uses this to draw conclusions about a particular cat, Felix.
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Inductive arguments on the other hand usually work the other way around. They being with some particular premise, which is based on a limited number of experiences and then use this as he basis of some universal claim about the world. In the example above the argument begins with some particular observation of Felix and then goes on to infer a general conclusion about all cats based on these limited observations.
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Now examine the arguments below and see if you can tell the difference.
Inductive
P1 - Fido is a dog.
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P2 - Fido is descended from wolves.
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C - So, all dogs must be descended from wolves.
Deductive
P1 - All dogs are descended from wolves.
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P2 - Fido is a dog.
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C - So, Fido must be descended from wolves.
Deductive Arguments
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In deductive arguments the conclusion does not go beyond what is contained in the premises.
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If we assume the truth of the original premise, and the argument is properly structured then we are compelled to accept the conclusion in a valid deductive argument.
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This means that the conclusion of a deductive argument is capable of being certain. The most common defining features of deductive and inductive arguments are:
Tasks
Complete the following tasks.
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Tasks can be found on your GoogleClassroom.
Cogent Argument
An argument is cogent (inductive strong) if and only if the truth of the argument's premises make the conclusion highly probable to happen.
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Let's look at the example below:
Cogent
Argument
Example
Without looking, Lauren pulled out 100 marbles from a bag; 95 of the marbles Lauren pulled out were red.
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Therefore, the next marble Lauren pulls out from the bag will be red.
The truth of the premise in this argument makes the conclusion highly probably to happen Therefore, this argument is cogent.
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A cogent argument is an inductive argument with true premises and high probability.
