We humans think all the time. Thinking impacts every decision we make, and yet, we rarely think about how we think. Critical thinking is a self-directed, clear, and careful way of thinking by which we take deliberate steps to think at the highest level of quality. It involves identifying the key points and false assumptions, recognizing the sources of information, evaluating evidence, and weighing up different types of arguments through structured reflection to draw justified, evidence-based conclusions.

Critical thinking is not about being skeptical, attempting to find flaws in others’ claims only, and negatively doubting everything but ourselves. Rather, it means tripping all the apples (Descartes’ analogy for our ideas, beliefs, opinions, and other forms of knowledge), ours and others, out of the basket and casting our eyes over each apple, putting back those we see after close, careful and logical examination as sound and leaving the others. Critical thinking is crucial when dealing with arguments that are either presented by others to persuade us or we formulate to persuade others

Before proceeding with the scrutiny and analysis of arguments, it is important to first pin down all sources of obscurity that may affect our clear thinking and lead to confusion or misunderstanding. This review summarizes 1) the three paramount sources of obscurity in speaking and writing: excessive vagueness, ambiguity, and generality, and 2) how definitions are used to reduce or eliminate these sources and for other purposes

To think critically, we must first think clearly. To achieve this, it is necessary to bear in mind the three major features of imprecise language that add confusion to claims and arguments. The first one is excessive vagueness, and it results when the scope of a concept is not clear. Vague terms are extremely common in natural language, and they admit to borderline cases, a completely determinate situation in which there is no correct answer as to whether the term applies to a certain object or not. The term ‘bald’, for instance, is vague because there is no precise number of hairs that mark the boundary between ‘bald’ and ‘not bald’. Similarly, the term ‘hot’ is also vague because there is no precise temperature that something must reach to count as hot. An example of vague claims is the statement ‘there are many people in the concert’ which does not give an image of the number of people that attended the concert.

The problem with the use of vague terms is that the receiver of the message, whether a listener or a reader, is not sure whether some particular things fall under them. They, therefore, render it impossible to establish the truth and falsity of the claims in which they appear. A typical example is that of sorites paradox: as grains of sand are removed from a heap, at what point does it cease to be a heap? It seems that the removal of a single grain of sand can never, by itself, transform a heap into a non-heap, but applying that idea consistently would entail that a heap is still a heap even when reduced to only a single grain.

It is important to know that vagueness occurs to varying degrees, and it is difficult to the point of impossibility to get rid of it entirely. As stated by Russell (1918), “Everything is vague to a degree you do not realize until you have tried to make it precise”. Therefore, when a claim is not too vague to convey appropriately everything the speaker intends it to (though sometimes vagueness is used intentionally), its level of vagueness is acceptable, but when it is not, vagueness becomes a problem. If a politician claims that he will raise taxes on the wealthy, then he must pin down just what he means by ‘wealthy’ since where the borders fall here makes a huge difference. On the contrary, if a person says that his brother is cold, then it is advisable to take his statement with a grain of salt without investigating where cold starts and where it ends.

Speaking of cold, the second linguistic phenomenon that can cause confusion and obscurity is ambiguity. Interestingly, the word ‘ambiguity’ itself, at least according to the Oxford English Dictionary, is ambiguous between two meanings: uncertainty or dubiousness on the one hand and a sign bearing multiple meanings on the other. Our concern is with the latter definition, the property enjoyed by linguistic signs, be it words, phrases, or sentences, that bear multiple (legitimate) interpretations (i.e., more than one meaning. The previous word ‘cold’, for example, can semantically mean both cold in temperature and feelings or personality. Likewise, the word ‘light’ is also ambiguous because it can mean ‘not-heavy’ or ‘not-very-dark’, etc. Words like ‘cold’, ‘light’, ‘saw, ‘bank’ ‘bat and ‘over’ are semantically ambiguous. They induce ambiguity in phrases or sentences in which they occur.

Nevertheless, phrases and sentences can be ambiguous even if none of their constituents is. The sentence ‘he saw a man on the hill with a telescope’, for instance, is structurally/ syntactically/ grammatically ambiguous - also known as amphiboly- as is the journal head title ‘actor sent to jail for not finishing the sentence’ or G. Marx’s famous joke “One morning, I shot an elephant in my pajamas; how he got in my pajamas I don’t know”. This type of ambiguity arises not from the range of meanings of single words, but from the relationship between the words and clauses of a sentence and the sentence structure underlying the word order therein (the sequencing).

Claims that are not properly constructed often create confusion and obscurity for readers or listeners. To illustrate this, the sentence ‘the professor said on Monday he will give an exam’, without punctuation, is subject to two interpretations: the professor talked to the class on Monday, and the exam will be given on Monday. Ambiguity can still have both a lexical and a structural basis, as with sentences like ‘He saw a bat’ (cut a wooden bat with a saw, saw the chiropteran animal, or cut the animal with the saw, etc.) or ‘time flies like an arrow; fruit flies like a banana’, and the like.

Other types of ambiguity include grouping ambiguity, a type of semantic ambiguity that results when it is not clear whether a word is being used to refer to a group collectively or to members of the group individually. A typical example is ‘Nurses make more money than doctors’. This type of ambiguity can lead to two venerable fallacies. the first is the fallacy of division which occurs when someone assumes that what is true of a whole must also be true of all or some of its parts. Another fallacy associated with this type is the ecological/population fallacy, the interpretation of statistical data that occurs when inferences about the nature of individuals are deduced from inferences about the group to which those individuals belong. Going the other direction, the fallacy of composition arises when one infers that something is true of the whole from the fact that it is true of some part(s) of the whole.

Another type of ambiguity is the ambiguous pronoun reference, a type of syntactic ambiguity. It occurs when a pronoun could refer to two or sometimes more possible antecedents. As a result, it is not clear to what or to whom the pronoun is supposed to refer. The presence of two or more distinct meanings for a single word or expression is a common, harmless, and often amusing feature of ordinary language that has been the source of much frustration and amusement for everyone who considers the interpretation(s) of linguistic signs. Yet, when unnoticed in the context of otherwise careful reasoning, it can lead to one of several informal fallacies.

Another notion that is closely related to vagueness and ambiguity is Generality. Overly general statements or claims are those that include words or phrases that are not specific enough to properly understand what they refer to and what they do not. The word ‘child’ is vague since it is not clear where the line is drawn between children and non-children. It can also be ambiguous (lexically) because it refers to both immature years and offspring. Besides, it is also general because it applies to both boys and girls. Similarly, the word ‘friend’ is general because it could mean a female friend and a male friend. Generality is a matter of “unspecification”: the fewer details a claim provides, the more general it becomes (Moore and Parker, 2009).

It is suggested that with all these potential pitfalls to clear thinking and clear communication, the best we can do is be clear about what our words mean. To achieve this, three types of definitions can be used. The first, definition by example (also called ostensive definition) specifies the meaning of an expression by pointing to examples of things to which the expression applies (e.g., by green I mean the color of grass, limes, lily pads, and emeralds). Ostensive definitions rely on analogical or case-based reasoning by the subject they are intended for, and they are often used when the term is difficult to define verbally, either because the words will not be understood or because of the nature of the term. It is usually accompanied by a gesture pointing out the object serving as an example. The second, definition by synonym refers to providing another word or phrase that has the same meaning as the term being defined. In this type of definition, the speaker uses a definiens- a linguistic expression that shares the same meaning- to clarify a definiendum- the word being defined. The third, the analytical definition, states the necessary and sufficient conditions for the definiendum and specifies the features that something must possess for it to be defined as such.

Each of these types of definitions can be used in a specific context to better illustrate and illuminate an obscure term. A person must be wise enough to determine which type is suited for each context. For example, if a person defined a horse as “quadruped, graminivorous, Forty teeth, namely twenty-four grinders, four eye-teeth, and twelve incisive, sheds coat in the spring, in marshy countries, sheds hoofs,…” (Bitzer’s definition in Hard Times), then he is likely to create more obscurity and confusion for his listener.

Besides their general purpose: telling what a word generally means (lexical definitions), three other functions can be fulfilled by definitions: Stipulative definitions are those that are used to amount to coinage of new words (neologisms) or define familiar words that are used in ways different from ordinary usage. Precision definitions are used to reduce vagueness or generality or to eliminate ambiguity. These definitions are common in law books (e.g. In this contract, the word ‘dollars’ will refer only to Canadian dollars, even if one party normally deals in U.S or Australian dollars). Finally, definitions can be used to persuade. These troublesome items are known as persuasive or rhetorical definitions and they are primarily designed to influence beliefs or attitudes using the emotive meaning of terms (the rhetorical force) instead of simply conveying linguistic information.

When a person employs these definitions, he or she uses the emotional connotation of a word or expression instead of one having a similar meaning but with less affective quality. Euphemisms, dysphemisms, hyperboles, cacophony, misleading analogies, and other rhetorical devices are the best examples (e.g. ‘murder’ when used instead of ‘homicide’ or ‘drunk’ instead of ‘inebriated’). Whether we define ‘abortion’ as ‘the murder of an unborn child’ or with abstract, clinical language that deflects our attention, or by saying that the woman is exercising her ‘choice’ to ‘terminate’ the pregnancy plays a crucial role in framing and influencing how we think about abortion far before we present arguments for or against it.

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Moore, Noel Brooke and Parker, Richard(2008). Critical Thinking. McGraw HillEducation.

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