“The fool does not desire understanding, but only the revelations of his heart” (Mishlei 18:2)
The wording of this pasuk is ambiguous. What is meant by “the revelations of his heart” and why should such an attitude toward tevunah, or understanding, characterize a person as a fool?
Rashi writes: But only the revelations of his heart: his desire is to reveal his heart, that which is in his heart.
In order to understand Rashi’s comments, we must first examine a fundamental principle of thought.
Albert Einstein is said to have defined “common sense” as “the collection of prejudices acquired by the age of eighteen.” Obviously Einstein did not mean for this statement to be taken literally. Rather, Einstein’s intention was to shed light on a commonly overlooked aspect of human psychology. Each and every person has a set of premises to which he ascribes validity. These premises may be ethical principles, religious beliefs, societal values, intuitive “gut feelings,” rules of etiquette, or even aphorisms or maxims. The origins of these premises differ depending on the particular person’s upbringing and environment. They may have been inculcated during youth by one’s parents or teachers, they may have been absorbed from society, or they may be products of one’s personality or emotions. Whether one realizes it or not, these premises greatly influence one’s thinking process and determine what information one decides to accept or reject and which authorities one chooses to trust or distrust. For example, it is likely that a person who was raised in a strictly religious home will be less likely to accept “secular ideas” than a person raised in a non-religious home. His premise is that “religious ideas” are valid and “secular ideas” are not. These premises usually take root at an age during which the person is either too young or too intellectually immature to notice their inception. Consequently, the majority of people will live their entire lives in ignorance of this important principle of psychology, examining neither the validity of their premises nor the manner in which these premises influence their thinking.
The average person views “learning” as the process of analyzing information and accepting that which makes sense and rejecting that which does not make sense. In actuality, however, people do not “learn” this way, contrary to what they may wish to believe. Rather “learning,” for most people, consists of accepting ideas, which are in agreement with their premises and rejecting ideas, which challenge or contradict them. Their criterion for accepting, and rejecting of ideas is not the inherent rationale of the ideas, but the ability of those ideas to conform to their premises. During a person’s youth, he is typically more open to accepting ideas, which differ slightly from his premises, but this limited stage of open-mindedness only lasts for so long. As a person continues in his learning he will begin to develop a framework based on the information he gleans. It is this framework, which Einstein would refer to as “the collection of prejudices.” It is this framework which will dictate all of one’s opinions and beliefs, guide one’s intuition and the way one approaches any new information, and will determine the position one takes on any given issue. Occasionally an idea will have a big enough emotional or intellectual impact to dramatically alter, or even uproot, a premise. Only in such instances will one’s framework undergo change. Unfortunately, such occasions are few in number and tend to decrease with time. Eventually, a person will reach a point at which his framework is so rigid and inflexible there is no longer a chance that any new ideas will be admitted. At this stage “we see only what we are prepared to see, what we have been taught to see. We eliminate and ignore everything that is not part of our prejudices.” By the time a person has reached this stage he has completely exhausted his intellectual integrity as well as his potential to advance in learning.
We can now understand Rashi’s interpretation of the pasuk, as well as the moral injunction of its author. The k’siel, or the fool, utilizes an erroneous approach to learning. Rather than treading the lonely and often perilous path of open-mindedness and independent thought, the k’siel chooses the path of least resistance, allowing his premises do all of the thinking on his behalf. Rather than struggling to withstand the clash of a rational idea with an irrational premise, the k’siel surrenders his mind to that irrational premise and discards the rational idea without giving it a second thought. He may claim to desire understanding, and he may even convince himself that this desire is real, but deep down the k’siel is only interested in that which is already in his heart, that which is in line with his premises, which he is already inclined to accept. For the k’siel, pursuit of wisdom is nothing more than a search to find ideas and opinions, which fit into his preexisting framework of beliefs.
The chacham, the wise man, on the other hand, utilizes the correct approach to learning. The first step he takes is to identify his premises. Once the chacham has identified his premises, he will then examine them to determine which are true and which are false, which of them have a basis in rationale and which have no basis at all. Once he has made this determination, the chacham will attempt to guard against the influence of his false premises. He will seek to understand precisely which areas of thought are likely to be affected by them. When studying those areas, he will check himself to make sure that his acceptance of the ideas is not based on the influence of his irrational premises. Whether the chacham succeeds in this difficult endeavor or not, it is clear from his attitude that he truly desires understanding. The willingness to step outside of his framework and contemplate an idea based on its own merit is what differentiates the chacham from the k’siel. Indeed, “the chacham’s eyes are in his head, while the k’siel walks in darkness.” A person should be guided by his framework - not blinded by it.
 Rabbeinu Shlomo ben Yitzchak (Rashi), Commentary on Sefer Mishlei 18:2
 From here and on, every mention of the word “premises” must be understood as a reference to this idea.
 In the Jewish world the term commonly used to describe such a framework is “hashkafa,” or outlook.
 Jean Martin Charcot, De l’expectation
 Sefer Kohelet 2:14