Rational thinking is characterized as one of the base structures of humanity. Without it the evolution of human race would not be as it is. It is so important that philosophers such as Aristotle were analyzing the aspect many years before the birth of Christ. For Aristotle the mind which was called the “nous” was functioning in many complex and different ways, for perceiving the world and the way of its existence. After many patterns he followed, based on rational thinking he suggested that none of things existing in actuality before thinking.
A simple definition given for rationality is: “One act is accordance with laws of logic “where logic does not describe the philosophy of reasoning with its flashes on insight and over sight, but it describes methods of justifying reasoning”. In Longmans Dictionary of contemporary English the definition given is “this which is based on clear, practical or scientific reasons. All these medical and technological achievements were accomplished with the use of logic combined with rational thinking, and furthermore civilizations invented sets of rules which would keep them existing and evoluting throughout the centuries.
Human reasoning works by receiving external stimuli, combining it with what it knows from memory, combining it with all other inputs ones environments, making a projection of what may happen in the future, taking into account miscellaneous other, factors, and then making a decision. What makes the decision to be good or bad is logic which is the study of correct reasoning. Aristotle founded the discipline of logic as a system of principles on which all others knowledge rests.
In logic we often refer to the two brad methods of reasoning as the deductive and deductive. Deductive reasoning works from the more general to the most specific. It follows a pattern of four major steps. The first is formal, a testing of the internal consistency of the theoretical system to see if it involves any contradictions. The second step is semi formal, and consists of the examination of the theory to distinguish between its empirical and its logical elements. In performing this step the person makes the logical form of the theory explicit.
Failure to do this can lead to category-mistakes, where the person ends up asking the wrong questions, and searches for empirical data where none are available. The third step is the comparing of the new theory with existing ones to determine whether it constitutes an advance upon them. If it does not constitute such an advance, it will not be adopted. If, on the other hand, its explanatory success matches that of the existing theories, it will be deemed to constitute an advance upon the existing theories, and will be adopted.
The fourth and final step is the testing of a theory by the empirical application of the conclusions derived from it. If such conclusions are shown to be true, the theory is corroborated. If the conclusion is shown to be false, then this is taken as a signal that the theory cannot be completely correct, and the person begins his quest for a better theory. He does not, however, abandon the present theory until such time as he has a better one to substitute for it.
More precisely, the method of theory-testing is as follows: certain singular propositions are deduced from the new theory. From amongst the latter the person next selects those which are not derivable from the current or existing theory. He then seeks a decision as regards these and other derived statements by comparing them with the results of practical applications and experimentation. If the new predictions are borne out, then the new theory is corroborated, and is adopted. If the predictions are not borne out, then they falsify the theory from which they are derived.
(Karl Popper, 1959)On the other hand inductive reasoning works the opposite way, moving from specific observations to broader generalizations and theories. Here the thinking person begins with specific observations and measures, starts detecting patterns and regularities, formulate some tentative hypothesis that he /she can make conclusions on theories. Such reasoning can be easily observed in chess playing. Players study the current configuration of the board and recall their opponents play in past games, to discern patterns.
They use these to form hypothesis or internal models about each others intended strategies, may be even holding several in their minds at one time. They make local deductions based on these, analyzing the positive implications of moves several moves deep, and as play unfolds they old onto hypothesis or mental models that prove plausible, they use a sequence of pattern recognition, hypothesis formation, deduction using hypothesis and replacement of hypothesis as needed for the game play. (De Grout 1965).
There are three major types of reasoning, syllogistic reasoning which was firstly introduced by Aristotle with the use of syllogisms and is the base of rational thinking, clearly shows the use of rules of logic in reasoning, conditional reasoning which involves heuristic processes schemas and background knowledge, and finally, every day reasoning which helps us cope with every day issues and is not such complicated as the other two types of reasoning. Evans in 1993 introduced two types of rationality the normative and the goal directed rationality.
Normative rationality is this of a person who is a member of larger groups of people and his acts reflect in a way on the group and this is why this type of rationality can be described as impersonal. Normative rationality follows the rules of logic and all the aspects which are scientifically proven. It is described as good when it follows these rules. On the other hand goal directed rationality is driven by emotions and expectations of an individual, and works for the benefits of a person. It does not follow sets of rules but occurs for the fulfilling of goals of individuals in certain occasions.
It is described as good when it comes to the outcome of fulfilling the goal of the individual. Jerry Fodor (1975) first introduced the concept of LOTH in the study reasoning. The language of Thought Hypothesis suggests that reasoning and thinking, take place in a mental language. This language consists of a system of representations that is physically realized in the brains and has a combinational syntax. According to LOTH thought is the tokening of a representation that has syntactic structure with appropriate semantics, thus thinking consists in syntactic operations defined over such representations.