Philosophical approaches to human thought often identified human mental "faculties" or sets of abilities.� Thomas Jefferson, for example, identified the three major human faculties asmemory, imagination, and reason. He organized his personal library to represent corresponding sections (eg. history, art and science).
Reasoning relies on forms of logic, a system of rules for making correct inferences. The two best recognized types of reasoning are inductive and deductive reasoning.
1. Inductive Reasoning
Inductive reasoning begins with specific facts or experiences and concludes with general principles. For example, one day you observe a particular bird, a bluejay, building a nest.� You might then inductively reason that all local birds have begun to build nests today. Since inductive reasoning makes inferences about an entire class based on only a few members of that class, it is an expedient but risky form of reasoning.
2. Deductive Reasoning
Deductive reasoning begins with general principles and applies these to particular cases.� For example, you know that in spring birds begin to build nests, and that today is the first day of spring.� You might then deductively reason that a particular bird you see in your neighbourhood is commencing to build a nest somewhere. Deductive reasoning is more conservative than inductive reasoning and generally more reliable.
3. Analogical Reasoning
An analogue is a likeness in form or proportion; for example, an analogue wristwatch is equipped with a dial like a clock or sundial, while a digital watch displays digits but not a dial.
An analogy is an inference that two things or ideas that are similar in some ways share other qualities as well. Analogical reasoning involves forming a concept about somthing new based on its similarity to something familiar.
For example, in the analogy, "tines are to fork as teeth are to comb," one must first understand the relation between teeth and comb - that "teeth" are the serrations in a comb - in order to conclude that "tines" must be the word for the prongs of a fork.
Analogical reasoning takes commonplace forms as well. For example, if you turn down a friend's request to borrow your car because "the last time you borrowed something of mine you ruined it"' you are drawing an analogy between the old behaviour and the new request, and making your decision by carrying the inference forward.