Logical reasoning is the process which uses arguments, statements, premises and axioms to define weather a statement is true or false, resulting in a logical or illogical reasoning. In today’s logical reasoning three different types of reasoning can be distinguished, known as deductive reasoning, inductive reasoning and abductive reasoning based on respectively deduction, induction and abduction.
Deductive reasoning originates from the philosophy and mathematics and is the most obvious form of reasoning. Deduction is a method for applying a general rule (major premise) in specific situations (minor premise) of which conclusions can be drawn. Example:
Major premise: All humans are mortal
Minor premise: Socrates is human
Conclusion: Socrates is mortal
Immediately the obviousness and straightforwardness of the conclusion can be drawn from the premises above of the example of deductive reasoning. Notice that deductive reasoning no new information provides, it only rearranges information what is already known into a new statement or conclusion.
The antithesis of deductive reasoning is inductive reasoning. In this form of logical reasoning specific conclusions are generalized to general conclusions. A famous hypothesis is ‘all swans are white’. This conclusion was taken from a large amount of observations without observing any black swan. Inductive reasoning however is a risky form of logical reasoning since the conclusion can as easily be incorrect when, looking at the swans example, a black swan is spotted. However, nowadays inductive reasoning is a commonly used type of reasoning in physics and philology.
Abductive reasoning is the third form of logical reasoning and is somewhat similar to inductive reasoning, since conclusions drawn here are based on probabilities. In abductive reasoning it is presumed that the most plausible conclusion also the correct one is. Example:
Major premise: The jar is filled with yellow marbles
Minor premise: I have a yellow marble in my hand
Conclusion: The yellow marble was taken out of the jar
The abductive reasoning example clearly shows that conclusion might seem obvious, however it is purely based on the most plausible reasoning. This type of logical reasoning is mostly used within the field of science and research.
Formal and Informal Logic Reasoning
Next to these 3 types of logical reasoning it is also possible to make a difference between formal reasoning and informal reasoning. Formal reasoning is a type of logical reasoning based on valid premises and therefore valid conclusions, thus it is a form of deductive reasoning. It provides no new information, but only rearranges known information to a new conclusion.
Next to formal reasoning we also have informal reasoning. This form of logical reasoning possesses all the elements of formal reasoning, like the deduction part, however it also includes probabilities and truths about premises and conclusions. It can be said that informal reasoning is related to abductive reasoning, one of the other three types of logical reasoning explained above
Combining these two forms of logical reasoning together with the three different types results in the following distinguish in logical reasoning:
Formal deductive reasoning
Informal deductive reasoning
Formal inductive reasoning
Informal inductive reasoning
Formal abductive reasoning
Informal abductive reasoning
Wrong can be Right Logically
Within logical reasoning it can sometimes happen that the premises and conclusion seem obviously wrong, but are logically speaking correct when applying one of the logical reasoning types mentioned above. Be aware that conclusions are drawn based on logical reasoning and not on the validity of the context of certain premises or conclusions. Example:
Major premise: Eating a lot makes you lose weight
Minor premise: Craig is obese
Question: What can we do to make Craig lose weight?
Conclusion: Make Craig eat a lot
By just observing the context of the words you would think that this conclusion is incorrect, since you know form everyday life that eating a lot does not make you lose weight at all. On the contrary it makes you gain weight. However based on logical reasoning this conclusion is most certainly correct, since both premises are valid, which automatically makes the conclusion a valid conclusion. What you need to understand is that the correct answer to any given logical reasoning argument requires the proper identification of relationships between assertions (typically facts and opinions), not the accuracy of those assertions.
Logical Reasoning in Aptitude Tests
Logical reasoning generally is a very important section in aptitude tests and/or IQ tests. Logical reasoning is universal and it is used in every form of reasoning, in every job, in every field every day. So if you have good logical reasoning skills you should be able to apply this everywhere. Better developed logical reasoning skills make you able to understand, analyze, and to question arguments based on statements or questions. These skills are in general used to identify clues that make an argument weaker, or to recognize a particular assumption. Logical reasoning can be tested in several different ways, however here on Fibonicci we offer the most important and most commonly accepted form of logical reasoning namely syllogisms.