HOW DOES EDUCATION PARALYZE INDEPENDENT THINKING? *
CRITICAL UNDERSTANDING AND CRITICAL THINKING IN SCIENCE EDUCATION
K. P. Mohanan
1.
A CRISIS IN SCIENCE EDUCATION
There has been a growing awareness all over the world that the current approach to science
education is unsatisfactory in many ways. Books by educators and professional scientific
journals devoted to research have repeatedly voiced this concern. In his book The
Unschooled Mind, for instance, Howard Gardner describes how otherwise competent
college students do not “really understand” what they have learnt, even when they show a
high degree of understanding in solving problems of the textbook type (Gardner 1993). In
his Science editorial, “Science: A Mountain or a Stream,” Don E. Detmer (1997) expresses
the warning: “If we remain dedicated to minor revisions of past educational approaches,
our prospects will be dim indeed.” In his Scientific American article in the section on
Trends in Science Education, Tim Beardsley (1992) documents an extensive list of similar
concerns. The 1991 Carnegie Commission on Science, Technology and Government states
that the situation is “a chronic and serious threat” to the future.
Educators and scientists have identified several possible causes for the situation, including
rote memorization and unintegrated knowledge. In this paper, I suggest that an important
factor that contributes to the problems of current science education is the failure to facilitate
critical understanding of scientific knowledge. My discussion involves three related
concepts:
transparent knowledge: a body of knowledge accompanied by evidence;
critical understanding: understanding of the knowledge with an awareness of the
evidence and argumentation; and
critical thinking: the process of critically evaluating knowledge claims.
Knowledge presented to students must be transparent in order to allow critical
understanding, and critical understanding is a prerequisite to critical thinking.
The point I wish to make in this paper is the following. A typical science education
program in most parts of the world offers non-transparent knowledge to students. This
disallows students from arriving at a critical understanding of the knowledge, disabling
them from engaging in critical thinking. The inhibition of critical thinking in a large
number of disciplines has the aggregate result of corroding the natural potential for critical
thinking in general. Thus, our educational programs paralyze the critical thinking faculty of
the younger generation. If we wish to remedy this situation, we must make scientific
knowledge transparent to the learners: the list of topics in science syllabuses must contain
issues of evidence, textbooks should present evidence and argumentation, and
examinations should test critical understanding.
Before I proceed, some clarification is in order. First, when talking of “science”, I include
not only the physical and biological sciences, but cognitive sciences like cognitive
psychology and generative linguistics, and social sciences like economics, sociology,
sociolinguistics, and political science. My point about the absence of critical understanding
applies to all these sciences.
*
I gratefully acknowledge Sunita Abraham, Desmond Allison, Alex Alsina, W.A.M. Alwis, Arun Bala,
Anjam Khursheed, Daphne Pan, Rani Rubdy, Wee Lian Hee, and Ravi Warrier for comments on earlier
drafts. Malavika and Tara Mohanan literally rewrote the paper, and transformed it into a readable form.
Second, there is a certain deep critical understanding of a belief that one can arrive at only
after having critically evaluated it and assimilated it into one’s belief system. On the other
hand, there is a certain basic critical understanding of evidence without which one cannot
critically evaluate a belief. The critical understanding that I am concerned with in this paper
is basic critical understanding.
Third, discussions of knowledge and thinking may be concerned with thinking in the
application of knowledge, or in the construction and evaluation of knowledge. This paper is
concerned with the second type of thinking, which is what goes into the making of future
scientists. My critique of traditional science education is that even at its best, it does not
facilitate the development of the thinking for knowledge construction and evaluation.
2.
KNOWLEDGE, EDUCATION, AND CRITICAL THINKING
2.1. Knowledge and Education
Knowledge is a set of propositions that an individual or community believes to be true. It is
fairly uncontroversial that institutionalized education has the responsibility of transmitting
a body of knowledge from the older generation to the younger generation. The current
scientific community believes that the earth revolves round its axis, that all matter is made
up of atoms, that water is not an element, and that the human species evolved gradually
from monocellular organisms on earth. Current science education transmits these beliefs to
the younger generation.
As knowledge advances, some beliefs included as part of knowledge get rejected, and
others get added. It is natural, therefore, that what is presented in textbooks will also
change with time. A few decades ago, science textbooks transmitted the belief that living
organisms consist of two kingdoms, namely, plants and animals, and that fungi belong to
the plant kingdom. Science textbooks these days reject the two kingdom system and
present a five kingdom system (Monera, Protista, Fungi, Plantae, Animalia) in which fungi
are neither plant nor animal. At a joint meeting of the Society of the Study of Evolution and
the Society of Systematic Biologists in 1996, biologists made the radical proposal that the
classificatory system of kingdom, phylum, class, order, family, genus, and species should
be abandoned, as it has no biological meaning, and can be misleading in the study of
evolution. In textbooks of the 21st century, we may therefore find a radically different
classification.
2.2. Transparent Knowledge
A knowledge claim is a proposition that is alleged to be correct. An important
characteristic of scientific knowledge is that knowledge claims are supported by evidence
and argumentation. Take, for instance, the following claim which is currently accepted as
part of “scientific knowledge”.
Common salt is made of sodium and chlorine.
This belief is based on experimental results. More than a century ago, the English chemist
Humphry Davis demonstrated that by passing electricity through it, salt can be separated
into two substances: a soft silvery metal, to which he gave the name sodium, and a
greenish-yellow gas, which had been named chlorine earlier. Conversely, it can also be
demonstrated that a sodium wire will burn in chlorine, producing salt. These two
experiments justify the belief that common salt is made up of sodium and chlorine.
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Typical textbook treatments, however, present such beliefs without evidence that supports
or conflicts with the beliefs. Knowledge presented without accompanying statements of
relevant evidence or the unavailability of evidence is opaque. Such knowledge is not open
to questioning and critical evaluation. Knowledge is transparent only when each
knowledge claim is accompanied by a discussion of evidence.
2.3. Critical Understanding
In the process of knowledge transmission, members of the adult academic community are
the producers of knowledge, and students, the consumers. The beliefs that get transmitted
to students are the conclusions arrived at by the academic community. If we want the
younger generation to be intelligent consumers capable of making decisions on their own,
the curriculum must present knowledge that is transparent, and provide for critical
understanding and critical thinking.
By critical understanding, I mean understanding of the propositions of knowledge, with
an awareness of the evidence for them. Take the following proposition found in
introductory textbooks in the physical sciences:
A molecule of water consists of two atoms of hydrogen and one of oxygen.
What are the reasons for believing this proposition to be true? Why can’t we assume that a
molecule of water consists of one atom of hydrogen and one of oxygen, as Dalton
originally proposed? Critical understanding involves answers to such questions. In
conventional science education, the commitment to presenting the reasons for accepting
claims is generally absent. As a result, students are prevented from achieving a critical
understanding of the knowledge they encounter.
2.4. Critical Thinking
We may view critical thinking as the mental process on the basis of which we make
reliable judgments on the credibility of a claim or the desirability of a course of action. The
members of a jury use their critical faculty to scrutinize the evidence presented in court to
decide if the accused is guilty. Members of a board of directors use their critical faculty to
decide if a proposed reform would be beneficial to the institution. Members of a scientific
community use critical thinking to judge the credibility of novel theories or experimental
results. A doctor uses critical thinking to assess the reliability of a diagnosis or treatment.
In academic disciplines, critical thinking is the process of assessing knowledge claims. For
instance, the proposition that there is life on Mars is a knowledge claim that is still under
scrutiny in the scientific community. The proposition that the universe is identical in all
directions is a knowledge claim which was previously taken as correct, but is currently
being re-scrutinized. We assess a knowledge claim by examining the evidence for it.
The knowledge claims in a discipline are evaluated by the specialists who form the research
community of that discipline. However, an intelligent non-specialist also needs to make an
estimate of the reliability of knowledge claims. I will use the term disciplinary critical
thinking to refer to the critical thinking that a specialist engages in, and general critical
thinking to refer to the critical thinking that an intelligent non specialist engages in. When
a professional physicist reads a research paper in physics, she uses disciplinary critical
thinking which involves the knowledge and thinking skills of physics. When the same
physicist reads an article on neuropsychology in Scientific American, or a newspaper report
on new evidence on the ‘Out of Africa’ hypothesis, she relies on her general critical
thinking which involves general knowledge and global thinking skills.
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For a non specialist, education must provide general critical thinking. When reading a
report on the alleged dangers of not taking sufficient calcium, and another report warning
against taking too much calcium, an intelligent non specialist should be able to arrive at an
informed estimate of how reliable the claims are. On the basis of available information, she
should be able to decide for herself if she should believe that there is life on Mars, or that
the human species originated in Africa. General critical thinking provides the intellectual
independence needed for such decisions.
Disciplinary and general critical thinking are obviously related. Deepening of disciplinary
critical thinking will naturally have the result of strengthening general critical thinking.
Furthermore, the larger the number and variety of disciplines in which students acquire
disciplinary critical thinking, the greater the range of strategies they can bring to bear in
general critical thinking. In other words, the best way to strengthen general critical thinking
in students is to help them acquire disciplinary critical thinking in a variety of subjects.
In what follows, I will argue that systematic inhibition of critical thinking does indeed take
place in conventional science education. I will first elaborate on what I mean by critical
understanding in science, and how it is related to disciplinary and general critical thinking.
I will then try to show how conventional science curricula do not provide for critical
under-standing. Finally, I will present a possible solution to the problem, and state what a
science curriculum must do to facilitate critical understanding and disciplinary critical
thinking.
3.
LEVELS OF UNDERSTANDING
As pointed out earlier, critical understanding is essential for critical thinking within a
discipline. Let us place critical understanding in the context of the goals of an educational
curriculum in terms of its knowledge component. One may view these goals in terms of
four levels of attainment:
A
B.
C.
D.
Familiarity: students are familiar with what is presented as knowledge in the
textbooks/classrooms.
Routinized understanding: in addition to (A), students have understood what is
presented as knowledge in the textbooks/classrooms such that they can apply the
knowledge to situations of the type routinely presented in textbooks/classrooms.
Genuine understanding: in addition to (B), students are able to apply the
knowledge to novel and unanticipated situations not encountered in the
textbook/classroom setting.
Critical understanding: in addition to (C), students have an understanding of the
relevant evidence (or lack of it) that bears upon the knowledge.
To illustrate, take the following questions involving Newton’s theory of motion.
(1) a.
b.
State Newton’s laws of motion and gravity.
A bomber plane is flying in a straight line at a speed of 300 miles an hour. When the
plane is 12800 feet vertically above point A on the ground, the pilot drops a bomb.
Calculate how far from A the bomb will land on the ground.
Familiarity with knowledge without understanding is rote learning. If we can answer (1a)
but not (1b), we have not understood Newton’s laws of motion and gravity. The task in (1a)
does not test understanding.
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The task in (1b) tests what I have called routinized understanding. Questions of this type
recurrently appear in students’ homework problems and quizzes. To answer this question,
students should have learnt the appropriate equations, and a set of skills and strategies for
calculation. Once these are learnt and internalized, they can be applied like a recipe. Thus,
(1b) demands routinized understanding with mechanical application.
In The Unschooled Mind, Howard Gardner cites a number of studies that indicate that
“students who receive honor grades in college-level physics courses are frequently unable
to solve basic problems and questions encountered in a form slightly different from that on
which they have been formally instructed and tested.” Take the following question:
What are the forces acting on a coin that has been tossed straight up and is still
continuing to move up?
This question does not belong to the normal textbook template of college physics. An
untrained person has the intuitive view that the coin is acted upon by both the downward
force of gravity, and the upward force of the hand. Someone who has genuinely understood
Newtonian physics should realize that the common sense intuition of the force of the hand
is wrong, and gravity is the only player (ignoring air resistance). Yet, 70 percent of college
students who had completed a course in mechanics gave the same naive answer as
untrained students, indicating that they had not achieved genuine understanding (see
McCloskey 1983 for more examples). Citing a wide variety of examples from subjects
ranging from physics and biology to sociology and history, Gardner demonstrates a serious
failure of our educational system in helping students move towards genuine understanding:
... essentially the same situation has been encountered in every scholastic domain in which inquiries have
been conducted. In mathematics, college students fail even simple algebra problems when these are
expressed in wording that differs slightly from the expected form. In biology, the most basic assumptions
of evolutionary theory elude otherwise able students who insist that the process of evolution is guided by
a striving towards perfection. College students who have studied economics offer explanations of market
forces that are essentially identical to those proffered by college students who have never taken an
economics course.
Gardner (1993: 4)
My own preoccupation is with the fourth level, namely, that of critical understanding,
which involves an appreciation of issues of evidence. Let me illustrate using two
hypothetical questions that call for critical understanding:
(2) The Greek philosopher Aristotle assumed that the universe is composed of four elements,
namely, earth, water, air, and fire. According to him, these elements occur in concentric
spheres. The natural place of earth (any solid substance) is the innermost sphere, and the
natural place of water is the next sphere, with air next, and fire the outermost. From the point
of view of a person standing on the ground, this means the earth is the lowest, with water
above it, air above water, fire being the highest. Aristotle’s law of motion states that elements
return to their natural places. When a stone is released up in the air, it returns to its natural
place, namely, the ground. When things burn, fire moves up instead, returning to the natural
outermost sphere.
a. What are the reasons for believing that Newton’s theory of motion is superior to
Aristotle’s?
b. There exist phenomena that Aristotle’s theory can explain, but Newton’s theory cannot.
Mention one of them, and explain why this phenomenon does not necessarily show the
superiority of Aristotle’s theory.
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(3) The impetus theory of motion was proposed by John Philoponus in the 6th century and
developed by Jean Buridan and others in the 14th century. According to this theory, setting
something in motion involves transferring an impetus from the mover to the thing moved.
When we throw a stone, impetus is transferred from our hand to the stone. When the impetus
is in a straight path, the object continues to move in a straight path; when the impetus is in a
curved path, it moves in a curved path. The impetus of a falling apple is straight, and hence it
continues moving in a straight line. The impetus of a spinning wheel is circular, and hence it
continues the circular motion.
On the basis of your knowledge of motion, identify the counterexamples to the impetus
theory of motion.
If a physics graduate cannot answer these questions, we must conclude that (s)he has not
attained the level of critical understanding with respect to Newton’s theory of motion, or
has not acquired the reading skill to understand the summary of the theories of motion in
the questions.
I must hasten to add that the reverse need not be true: successful answers to these questions
do not necessarily point towards critical understanding, as it may very well be that the
answers are available in class notes, and that the student is regurgitating these answers,
without really understanding the evidence and argumentation. All that we can reliably say
is that failure to provide a satisfactory answer points to a lack of critical understanding.
4.
CRITICAL UNDERSTANDING IN SCIENCE: FACTS VS. THEORIES
Critical understanding presupposes an appreciation of how knowledge claims are justified
in the given discipline. What does it take to understand the evidence for a knowledge claim
in science? The first step towards critical understanding is to develop an awareness of the
distinction between facts and observations on the one hand, and theories and theoretical
interpretations of these facts on the other. The second step is an appreciation of how
factual and theoretical claims are justified in the sciences.
4.1. Factual and Theoretical Claims
Take, for instance, the propositions in (4).
(4) a.
b.
Common salt is made up of sodium and chlorine.
A molecule of common salt consists of one atom each of sodium and chlorine.
Common salt, sodium, and chlorine are labels for observable entities. The proposition in
(4a) states an observable relation between these entities, and hence is a factual claim. In
contrast, molecules and atoms are labels for unobservable hypothetical constructs that
scientists have postulated as part of their explanation of observable facts. Hence, the
proposition in (4b) is a theoretical hypothesis which forms part of the scientist’s
interpretation of facts. In other words, (4a) is a factual statement, and (4b) is a theoretical
statement. By ‘observable’, I mean something that (a) the human sensory apparatus can
perceive, (b) normal individuals do not have disagreements about, and (c) we have no
reason to question the reliability of.
As another example, take the statement that when we hold a coin above a table and drop it,
it moves down in a straight line and lands on the table. This is a factual statement. We can
directly observe the coin moving down. However, we are not making a factual statement
when we say that the coin falls because of the gravitational force of the earth. The assertion
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about gravity is a theoretical hypothesis, one of the pieces in a theoretical interpretation that
explains the observed facts.
To summarize then, factual claims are formulated in terms of observable entities. In
contrast, theoretical claims often involve unobservable hypothetical entities. We can
observe the falling of a coin, an effect that theoretical physics attributes to gravity, but
gravity itself is not observable. It is a hypothetical construct that scientists have invented.
Other examples of hypothetical constructs include magnetic field, electric charge, kinetic
energy of molecules, valence, chemical bonds, electronic orbits, electron spin, genetic
program, black hole, time-space continuum, and so on. As Einstein and Infeld (1935:31)
point out unambiguously, such constructs of theoretical science are inventions of the
human mind, not deducible from any set of observations.
The first step towards a critical understanding of scientific knowledge involves a clear
separation of facts and theories. Very few science textbooks are sensitive to this distinction.
The result is the widespread illusion that science is a collection of established facts.
4.2. Justifying Theoretical Claims
We justify factual claims by demonstrating that our observations are consistent with the
factual claims. We justify theoretical hypotheses by demonstrating that they are an
essential part of the best explanation for a set of observable facts.
Let us go back to the issue of critical understanding in relation to the propositions in (4):
(5) a.
b.
c.
Why should we believe that common salt is a compound made of sodium and chlorine?
Why should we believe that a molecule of sodium chloride consists of one atom of
sodium and one of chlorine?
Why should we believe that there are such things as atoms?
(5a) deals with a factual claim; we saw earlier the experimental evidence for this claim.
(5b) and (5c) deal with theoretical claims that form part of a theoretical explanation. These
theoretical hypotheses are justified by the demonstration that they are a necessary part of
the best explanation for a set of observable facts. In a textbook meant for college students,
Pauling (1955) gives the following answer to question (5c):
In 1785 the French chemist Antoine Laurent Lavoisier (1743-1794) showed clearly that there is no
change in mass during a chemical reaction — the mass of the products is equal to the mass of the
reacting substances. This general statement is called the law of conservation of mass.
In 1799 another general law, the law of constant proportions, was enunciated by the French
chemist Joseph Louis Proust (1754-1826). The law of constant proportions states that different
samples of a substance contain its elementary constituents (elements) in the same proportions. For
example, it was found by analysis that the two elements hydrogen and oxygen are present in any
sample of water in the proportion by weight 1:8. One gram of hydrogen and 8 grams of oxygen
combine to form 9 grams of water.
Dalton stated the hypothesis that elements consist of atoms, all of the atoms of one element
being identical, and that compounds result from the combination of a certain number of atoms of one
element with a certain number of atoms of another element (or, in general, from the combination of
atoms of two or more elements, each in definite number). In this way, he could give a simple
explanation of the law of conservation of mass, and also the law of constant proportions.
A molecule is a group of atoms bonded to one another. If a molecule of water is formed by the
combination of two atoms of hydrogen with one atom of oxygen, the mass of the molecule would be
the sum of the masses of two atoms of hydrogen and an atom of oxygen, in accordance with the law
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of conservation of mass. The definite composition of a compound is then explained by the definite
ratio of atoms of different elements in the molecules of a compound.
Dalton also formulated another law, the law of simple multiple proportions. This law states
that when two elements combine to form more than one compound, the weights of one element which
combine with the same weight of the other are in the ratios of small integers. It is found by
experiment that, whereas water consists of hydrogen and oxygen in the weight ratio 1:8, hydrogen
peroxide consists of hydrogen and oxygen in the ratio 1:16. The weights of oxygen combined with
the same weight of hydrogen, one gram, in water and hydrogen peroxide are 8g and 16g; that is, they
are in the ratio of small integers 1 and 2. This ratio can be explained by assuming that twice as many
atoms of oxygen combine with an atom of hydrogen in hydrogen peroxide as in water.
Pauling (1955:28-29)
The argument for atomic theory involves the statement of a set of facts, stated above as the
laws of conservation of mass, constant proportions, and simple multiple proportions. It also
involves the statement of how the facts lead to the justification of the theoretical claim. To
see the logic of the argument more clearly, let us state the bare essentials of Pauling’s
argument as follows, supplying the missing steps.
On the basis of experimental observations, we are justified in concluding that the law of
conservation of mass, the law of constant proportions, and the law of simple multiple
proportions, are correct.
The assumption that elements are composed of atoms yields a simple explanation for these
experimental laws.
In the absence of evidence to the contrary, we accept this explanation, and conclude that the
atomic hypothesis is correct, until we find a better or equally good explanation for these laws.
The abstract structure of this argument is schematized as follows:
We observe Q.
If we postulate P, we can explain Q. Therefore P is a desirable theory.
In the absence of evidence to the contrary, we accept P as correct, until a better
explanation becomes available.
Note the appeal to the explanatory power of the theory, as well as the absence of total
certainty in the conclusion. These are the two essential hallmarks of theoretical science.
Critical understanding of scientific knowledge presupposes a familiarity with the structure
of scientific argumentation illustrated above, and an appreciation of the tentativeness of
scientific knowledge.
Unfortunately, the necessary ingredients of critical understanding are missing in most
science textbooks. They do not spell out how the three laws that Pauling mentions yield an
argument for atomic theory. They do not even state that the two are connected. Finally,
they do not carry a sense of the tentativeness of scientific theory, thus creating the illusion
that the propositions of theoretical science are facts.
Let me take one more example of evidence for theoretical hypotheses in science. Every
school student is told that the earth rotates around its axis once a day. Now, the alleged
rotation of the Earth is not observable from the Earth. All that we can observe from within
the solar system are the changes in the observed positions of the objects in the sky in
relation to the earth. The earth’s rotation is not a fact, but a hypothesis, an interpretation
that allows us to explain a set of facts. The justification for believing this hypothesis is that
we need to make this assumption in order to explain the observed facts. Hence, providing
evidence for this hypothesis involves answering questions (6a-d):
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(6) a.
b.
c.
d.
e.
What facts support the hypothesis that the Earth rotates around its axis?
How do these facts support the hypothesis?
Are there any facts that challenge the hypothesis?
Can the facts be interpreted in terms of an alternative hypothesis?
If there are alternatives, which is the best one? Why?
At the high school level, an answer to the first two questions can be stated along the
following lines. Let us take a look at the night sky from the earth. Though the stars in the
night sky keep changing their locations at different rates, the North Star, also called Polaris,
hardly changes its location. From the reference point of an observer on earth, the stars near
Polaris appear to move around Polaris in circles. When they are above Polaris, they move
from east to west, and continue moving under Polaris from west to east. The stars farther
away from Polaris move from east to west and then slip below the horizon, when we can
see them no longer. The Sun and the Moon move from east to west and then dip under the
horizon in the same fashion. Why does the sky appear to move in this systematic fashion
day after day?
Let us imagine that the sky is like a huge basketball, and the earth is like a huge tennis ball
suspended inside the basketball. We are ants sitting on the tennis ball, staring at the stars
studded on the inside of the basketball. The observed changes in the location of the stars
can then be due to the rotation of the tennis ball inside the basketball:
The observed facts
In relation to the Earth, Polaris does not change its position, but the other stars move in
circles around Polaris. Why does the sky appear to move in this systematic fashion every
day?
An explanation
Let us assume that the Earth rotates around the axis connecting the Earth and Polaris.
From this assumption, it would follow that for an observer on earth, the position of
Polaris would appear fixed, and the other stars would appear to describe a circular
motion around Polaris.
Argument
The facts cited above can be successfully explained if we assume that the earth rotates
around its axis. In the absence of a better or equally good explanation, we accept the
explanation in terms of the earth’s rotation.
The argument for the Earth’s rotation crucially relies on the explanation for the observed
changes in the positions of the stars. The explanation is satisfactory, and there are no facts
which contradict this explanation. At this point, however, it would be natural to ask if our
explanation is the best one, even the only one for the observed facts. Are there alternative
explanations which can account for these facts? Let us take the most obvious one:
An alternative explanation
Let us assume that the whole sky, with all its stars rotates around the axis connecting the
Earth and Polaris. From this assumption, it would follow that for an observer on earth,
the position of Polaris would appear fixed, and the other stars would appear to describe a
circular motion around Polaris.
A few centuries ago, Ptolemy chose the hypothesis of the rotation of the sky, and
constructed a theory on the basis of which the positions of celestial bodies can be calculated.
Following Copernicus, modern astronomy has chosen the hypothesis of the Earth’s rotation
instead, and constructed an alternative theory. Critical understanding of the hypothesis of
the rotation of the Earth demands that students also understand why this hypothesis is
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superior to the hypothesis of the rotation of the sky. The traditional answer is that the latter
leads to a simpler analysis, the details of which may be beyond the level of the high school
student. What is important for the student, however, is the awareness that the superiority of
the modern theory rests on the promise of a simpler analysis.
In sum, the relation between facts and theories in scientific knowledge is as given below:
facts
/\ <— ARGUMENTATION
... theory–x ... theory–y ...
A scientific theory is an explanation for a set of observed facts. A given body of facts can
be explained by more than one theory. A factual claim is justified by appealing to
observation, while a theoretical claim is justified indirectly by appealing to the ability of
the claim to satisfactorily explain established facts. The chain of reasoning that connects
the theory to the facts and thereby justifies theoretical claims is argumentation.
4.3. Fallibility of Scientific Knowledge
Factual claims, once established, cannot be overturned on the basis of additional evidence
or alternative ideas. In contrast, established theoretical claims can be overturned. The
history of science is full of examples of theoretical claims that were accepted as true at
some stage, but were subsequently rejected as false:
John Dalton, the founder of the atomic theory, believed that a water molecule consisted of
one atom of oxygen and one atom of hydrogen, and that the atomic weight of oxygen was
eight. Subsequent evidence showed that Dalton was wrong: twentieth century chemistry
subscribes to the belief that a water molecule has two atoms of hydrogen, and that the
atomic weight of oxygen is sixteen.
Dalton also believed that atoms are indivisible. This idea was replaced by the idea that an
atom is made up of a nucleus and one or more electrons.
In 1898, J.J. Thomson proposed that atoms are clumps of matter with electrons embedded
in them, like raisins in a fruitcake. This idea was soon rejected, and replaced by
Rutherford’s idea that electrons orbit around the nucleus like planets, with empty space
between them.
During the early twentieth century, it was believed that electrons, protons, and neutrons are
elementary particles which cannot be broken down further. Today, scientists believe that
both protons and neutrons consist of still smaller particles called quarks.
Newton believed that time and space do not interact, a hypothesis which was rejected by
Einstein who assumed that time and space do interact.
Both Newton and Einstein believed that the universe is identical in all directions, a
hypothesis which is currently being challenged by what looks like evidence for the idea of
an axis in the universe.
Contrary to the illusion created by conventional textbooks, theoretical science does not
offer certain and infallible knowledge: uncertainty and fallibility are inescapable properties
of scientific knowledge. A recognition of this characteristic is foundational to critical
under-standing and critical thinking in science.
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5. LEVELS OF CRITICAL UNDERSTANDING
The critical understanding of a body of scientific knowledge may be pursued at different
levels of abstraction. It would be useful to distinguish the following levels:
Representations of entities in terms of theoretical concepts;
The theory itself;
The conceptual framework of the theory;
The value system that underlies critical evaluation of the theory.
Let us take a brief look at each of these levels.
5.1. Representations
The term ‘representation’ refers to the interpretation of a particular entity or state of affairs
in terms of the concepts of a theory. Thus, given the axioms of atomic theory, we explain
the observed pattern of the compositional behaviour of water by assuming that a molecule
of water consists of two atoms of hydrogen and one of oxygen. This representational
assumption is expressed by the formula H2O. Similarly, the formulae CH4, C2H6, C3H8,
C2H4, and C6H6 express the theoretical representations of methane, ethane, propane,
ethene, and benzene respectively.
It is important to realize that although a theory constrains the possible types of
representations, the theory by itself does not uniquely determine the representations of
particular entities. Had the experimental results been different, we might have represented
water as HO, or H4O. The theory gives us the option from among a number of
representations to fit the observed data. It is the combination of the theory and the observed
data that justifies our representational assumptions.
Given the axioms of structural chemistry, the representations of the structure of molecules
become more sophisticated. To illustrate, the standard representations of methane, ethane,
and propane, and ethene are given below:
methane
H
|
H–C–H
|
H
ethane
H H
| |
H–C–C–H
| |
H H
propane
H H H
| | |
H–C–C–C–H
| | |
H H H
ethene
H
\
/
H
H
/
C=C
\
H
These pictures do not represent observable facts, but what scientists have assumed to be the
hidden structure of molecules. Hence, critical understanding of representations involves an
understanding of issues such as the following:
(7)
a.
Granted that a molecule consists of atoms, why should we assume that a molecule of
water contains two atoms of hydrogen and one of oxygen? Why can’t we assume that it
contains one atom of each, as Dalton originally did?
b.
Granted that the concept of valence is justified, why should we assume that oxygen has
a valence of two and carbon, a valence of four?
c.
Granted that we need the concepts of atoms and electrons, why should we assume that
a hydrogen atom has one electron while a helium atom has two?
d.
Granted that a hydrogen atom has a single electron, why should we assume that the two
nuclei in a molecule of hydrogen share their electrons?
11
e.
Why should we define valence in terms of structural links as in the representations
above? For instance, instead of assuming that in ethane, each carbon atom has four
links (three to hydrogen atoms and one to the other carbon atom), why can't we assume
that carbon has an alternate valence of three? Likewise, why should we assume that
ethene has a double bond, symbolized by the double line between the two C’s in its
representation? Why can’t we account for the number of atoms in ethene by assuming
that carbon has a valence of two in ethene?
5.2. Theories
A scientific theory is a set of logically related laws and definitions. The questions below
illustrate ways of evaluating scientific theories:
(8) a.
b.
c.
d.
Why must we assume that an atom of an element has the same properties as any other
atom of the same element?
Why should we accept Avogadro’s hypothesis that equal volumes of all gases contain
equal number of molecules at the same pressure and temperature?
Why should we believe that Rutherford’s model of the atom is better than Thomson’s
model? That is to say, why should we assume that there is empty space between the
nucleus and electrons?
Why should we believe that Bohr’s model of the atom is better than Rutherford’s? In
other words, why should we accept that:
(i)
electrons circle around the nucleus in an orbit without losing energy;
(ii)
the orbits are universally defined for all atoms; no electron in any atom can exist
between two such orbits;
(iii) the energy of an electron depends on which orbit it is in; the larger the orbit, the
greater the energy; and so on.
5.3. Conceptual Frameworks
Some of the concepts of science that high school and university students are exposed to
include force, mass, weight, distance, displacement, time, velocity, acceleration,
momentum, gravity, magnetic field, electric charge, molecule, atom, valence, chemical
bond, nucleus, electron, proton, neutron, atomic number, atomic weight, electron orbits,
electron spin, electron shell, and so on. These concepts constitute a conceptual framework,
that is, a set of related concepts for explaining or describing phenomena. Scientific theories
are constructed in terms of these concepts. Newton’s laws, for instance, employ the
concepts of force, mass, weight, distance, displacement, time, velocity, acceleration,
momentum, and gravity. Rutherford’s model of the atom crucially appeals to the concepts
of atom, electron, and orbit, but not the concepts of electron spin or electron shell. Critical
understanding at this level consists of an understanding of the justification for accepting the
propositions in (9) and (10):
(9) a. Why must we assume entities such as atoms and molecules?
b. Why must we assume molecules in addition to atoms?
c. Why must we assume valence?
d. Granted that we need the concepts of molecules and atoms, why must we assume atomic
nuclei and electrons?
e. Granted that we need to assume atomic nucleus, why must we assume protons and
neutrons?
f. Why do we need the concept of electron orbit?
g. Why do we need the notion of chemical bonds in addition to the notion of valence?
12
(10) a. What are the reasons for rejecting the Greek concept of elements and accepting the
modern concept of elements?
b. What are the reasons for rejecting Ptolemy’s concept of planets and accepting the
modern concept of planets?
c. What are the reasons for rejecting the concept of ether?
d. Why must we reject the concept of atom as an indivisible unit of matter?
5.4. The Value System
The central elements of the value system common to the physical and biological sciences
(not necessarily shared by many of the social sciences) are given below:
A theory should derive correct predictions of observed facts; a theory that makes incorrect
predictions should be rejected or modified.
We believe that Nature does not contain logical contradictions. Hence we cannot accept
scientific theories that contain logical contradictions.
The predictions of a theory should be as general as possible.
We believe that Nature is ultimately simple. Hence scientific theories must be as simple as
possible. Given two competing theories which are equal with respect to the above criteria,
we choose the simpler one.
Critical understanding of the value system of a discipline calls for an appreciation of the
alternative value systems in other disciplines. In mathematics, for instance, we take the
initial postulates as given (e.g. Euclid’s postulates), and justify the theorems by
demonstrating that deductive reasoning yields these theorems from the initial postulates
(e.g. the proofs of Euclid’s theorems). In theoretical sciences, the counterparts of initial
postulates are the theoretical hypotheses. We demonstrate that deductive reasoning yields a
set of predictions from the theory, that these predictions match observed facts, and then
justify the theory on the basis of the correctness of predictions. The value system in
mathematics does not include the correctness of predictions. The value system in history,
on the other hand, includes neither predictions nor deductive reasoning.
At the level of the value system, critical understanding calls for the acknowledgment of
something akin to an intuitive faith in the belief that Nature does not contain logical
contradictions, Nature is ultimately simple, and Nature is amenable to rational exploration.
It is important that students appreciate that no further rational justification of the value
system is really possible. Very few textbooks are sensitive to the value system of scientific
justification. As a result, very few science students are exposed to these issues.
5.5. Critical Understanding and Independent Thinking
It should be clear by now that one can be critical of knowledge claims in science at various
levels. The lowest level is that of representations. A student may accept as given the
context of the value system, the framework of theoretical concepts, and a particular theory
in terms of the framework, and yet question the particular representations proposed in
science. The next level is that of the theory. A student may accept as given the context of
the value system and the framework of theoretical concepts, and yet question the particular
theory constructed out of the framework. Questioning the framework itself is the next level
of critical understanding. An appreciation of the nature and limitations of the value system
that underlies critical evaluation is the most abstract level of critical understanding. The
background assumptions within which each of these levels of critical understanding are
located can be pictured as follows:
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_____________________________________
______________________________
________________________
__________________
REPRESENTATIONS
__________________
THEORY
________________________
CONCEPTUAL FRAMEWORK
______________________________
VALUE SYSTEM
_____________________________________
As many philosophers and scientists have pointed out, science may be thought of as the
activity of discovering and solving puzzles (Kuhn (1970)). The picture above shows
various levels of creative and critical activities associated with puzzle solving. At the
lowest level, creative and critical activity will be solving puzzles and evaluating the
solutions in the context of a given theory, framework, and value system. At a higher level,
creative and critical activity will involve solving puzzles by constructing novel theories,
and critically evaluating existing theories. At the next level, creative and critical thinking
involves solving puzzles by constructing novel theories that involve novel concepts or
novel conceptual frameworks. The highest form of critical thinking would involve being
critically aware of the limitations of the value system of the community, and of how this
value system differs from alternative value systems.
It would be unrealistic to expect beginners to practice critical and creative thinking at the
levels of theory and framework in a technical disciplines like physics and chemistry.
However, it is not unrealistic to expect beginners to achieve a critical understanding at all
these levels, such that when their technical mastery of the discipline increases, the doors are
open for critical thinking at any of these levels.
6. SCIENCE EDUCATION, CRITICAL UNDERSTANDING, CRITICAL THINKING
6.1. Absence of Critical Understanding in Science Education
In the preceding sections, I suggested that critical understanding is a precondition for
disciplinary critical thinking, and that critical understanding in science requires the
following ingredients:
Familiarity with the observations relevant for critically evaluating a factual claim.
Familiarity with facts relevant for critically evaluating a theoretical claim.
An understanding of how the facts justify or refute the theoretical claim.
An understanding of how a hypothesis or theory is superior to its alternatives.
An awareness of the distinction between facts and theories.
An understanding of the value system of science and the modes of argumentation that rely
on this value system.
An appreciation of the uncertainty and fallibility of scientific knowledge.
I have not found these ingredients in the prescribed science textbooks that I have looked at.
The syllabuses, textbooks, and examinations in current science education in most parts of
14
the world do not provide for critical understanding. The types of questions in (2)–(3) and
(5)–(10) seldom figure in science textbooks or examinations.
I am not saying that all science textbooks fall into this category. There are indeed some
that aim at critical understanding. Some of the best that I am familiar with include Einstein
and Infeld’s Evolution of Physics, Richard Feynman’s Character of the Physical Law, and
Lectures in Physics, Leon Cooper’s An Introduction to the Meaning and Structure of
Physics , and Isaac Asimov’s Atom. Such books, however, do not seem to be popular for
some reason with those who make decisions on what to prescribe.
6.2. Inhibition of Critical Thinking
Because traditional science education does not provide for critical understanding, it fails to
provide the environment for the development of disciplinary critical thinking. This has an
immediate consequence. General critical thinking strategies are developed through the
practice of disciplinary critical thinking in particular disciplines, and then gradually
extending these strategies outside their boundaries. I take it that critical understanding is a
pre-requisite to disciplinary critical thinking, and disciplinary critical thinking is essential
for general critical thinking. It follows that the current system of education is detrimental to
the development of general critical thinking. This flaw cannot be remedied by offering
discipline-free decontextualized courses in critical thinking.
The absence of critical understanding in science education has a greater danger. Traditional
science textbooks provide conclusions in science without the supporting evidence, thereby
transmitting what I have called opaque knowledge. This forces students to accept beliefs
without questioning, and promotes an unscientific attitude towards knowledge. The result
is that of indoctrination:
What really constitutes scientific education is not the content that we transmit, but the spirit
of the scientific enterprise. This spirit, which is missing in most science curricula, is
expressed by Richard Feynman as follows:
The scientist has a lot of experience with ignorance and doubt and uncertainty, and this experience is of
very great importance, I think. When a scientist doesn’t know the answer to a problem, he is ignorant.
When he has a hunch as to what the result is, he is uncertain. And when he is pretty darn sure of what
the result is going to be, he is still in some doubt. We have found it of paramount importance that in
order to progress we must recognize our ignorance and leave room for doubt. Scientific knowledge is a
body of statements of varying degrees of certainty — some most unsure, some nearly sure, but none
absolutely certain.
Now, we scientists are used to this, and we take it for granted that it is perfectly consistent to be
unsure, that it is possible to live and not know. But I don’t know if everyone realizes this is true. Our
freedom to doubt was borne out of a struggle against authority in the early days of science. It was a very
deep and long struggle: permit us to question — to doubt — to not be sure. I think that it is important
that we do not forget this struggle and thus lose what we have gained. Herein lies a responsibility to
society.
Feynman (1988:245)
In his book Frames of the Mind: The Theory of Multiple Intelligences, Howard Gardner
expresses a similar view:
While both scientific and nonscientific or pre-scientific ways of thinking are efforts to explain the
world, there remains a fundamental difference between them. Specifically, in its effort to explain the
world, the scientific mind includes a credo that involves the positing of hypotheses, the stipulation of
the conditions under which a hypothesis can be rejected, and the willingness to abandon the hypothesis
15
and to entertain a new one should the original one be disconfirmed. Hence the system is inherently open
to change. The pre-modern or nonscientific mind has available all the same thought processes as has the
scientific mind, but the system within which the former works is essentially closed: all premises have
already been stated in advance, all inferences must follow from them, and the explanatory system is not
altered in the light of the new information that has been procured. Rather, in the manner described in
traditional religious education, one’s rhetorical powers are simply mobilized to provide ever more
artful justifications of the conclusions, world views, that were already known in advance for all time.
Gardner (1983: 362)
Whether it is Darwinism or Creationism, whether it is Ptolemy or Newton, whether it is the
Greek theory of elements or Dalton’s theory of elements, if we force our students to accept
what we believe without giving them a chance to scrutinize the evidence and make up their
minds on their own, we are training them to be superstitious, not scientific.
6.3. Inhibition of Creative Thinking
Opaque knowledge in science education has the consequence of suppressing creative
thinking as well. In the context of scientific knowledge, creative thinking is the mental
activity involved in the production of new knowledge. We recognize creativity in the
discovery of new facts, novel designs of experiments, construction of theoretical
explanations, pursuit of alternatives, and invention of novel theoretical constructs. In most
cases, such creative activity is made possible by a critical assessment of the existing body
of knowledge. Absence of critical activity would inhibit creative activity.
It may be useful to distinguish between creativity at the level of the individual and
creativity at the level of the research community. Boden (1992) refers to former as
P-creativity and the latter as H-creativity. Imagine a group of students who have not yet
been exposed to the laws of motion. The teacher draws their attention to a number of facts
of motion, such as objects falling in a straight line, objects sliding a greater distance on a
polished surface than on a rough surface, and so on. To explain such facts, the students
construct a crude version of Newton’s laws of motion. In this scenario, the students create
knowledge which is novel for them, but not for the research community in physics. Their
activity is P-creative.
It would be unrealistic to expect school and college students to be H-creative, and make
original contributions to existing knowledge. However, there is nothing unrealistic about
expecting them to be P-creative. Practice of such creative thinking in the classroom would
facilitate H-creativity over time. Denying critical understanding to students is denying the
creative path that ultimately leads to making original contributions to existing knowledge.
7.
A POSSIBLE SOLUTION TO THE CRISIS
To summarize, I made the following points on the relation between knowledge, education
and thinking.
Institutionalized education has two related goals: knowledge and thinking abilities.
Knowledge is a set of propositions that we believe to be true. We may view the mastery of
knowledge in terms of four levels: familiarity, routines understanding, genuine
understanding, and critical understanding.
A transparent body of knowledge is accompanied by evidence that bears upon the
knowledge claims, or an explicit acknowledgment of the absence of available evidence.
Given transparent knowledge, the receivers of knowledge can judge for themselves
16
whether to accept or reject what is offered. If this requirement is not met, what we have is
opaque knowledge. Opaque knowledge is not open to challenge, questioning, and
modification, and hence is unscientific in spirit.
Critical understanding of a body of knowledge involves the awareness of the evidence and
argumentation that supports or challenges that knowledge.
Critical thinking is the mental activity of judging the credibility of a knowledge claim.
Disciplinary critical thinking is the specialist’s mental activity of judging the credibility of
the discipline internal knowledge claims in the context of the value system and knowledge
internal to that discipline. General critical thinking is the intelligent non specialist’s mental
activity of evaluating knowledge claims on the basis of global critical values and general
knowledge.
Critical understanding is a pre-requisite to disciplinary critical thinking.
On the basis of these remarks, I advanced the following criticism of existing science
education:
Conventional science education as currently practiced in most parts of the world generally
transmits opaque knowledge to students. This is contrary to the very spirit of science.
By indoctrinating students with opaque knowledge and denying them critical
understanding, conventional education in science (as well as non-science subjects) makes
them incapable of subjecting the knowledge to disciplinary critical thinking, and forces
them to accept the beliefs taught to them.
This state of affairs has the effect of paralyzing not only their ability for disciplinary critical
thinking, but also their natural potential for general critical thinking, and creative thinking.
A solution to this undesirable state of affairs is to incorporate issues of evidence and
argumentation into the curriculum for every subject, from primary school to graduate
school. We can make a beginning by requiring students to read books such as Einstein and
Infeld’s Evolution of Physics, Asimov’s Atom, John Ziman’s Reliable Knowledge, and so
on. The next step would be to build transparent knowledge and critical understanding into
the curriculum. Such an enterprise, in my view, would involve the following ingredients:
There should be a clear awareness of the distinction between factual and theoretical claims
for each new piece of knowledge.
For each piece of knowledge, there should be a discussion of the relevant evidence, and a
clear acknowledgment of the absence of evidence or of the existence of counterexamples
where relevant.
For theoretical claims, evidence would include the presentation of arguments in support of
each theoretical representation, theoretical law, and theoretical concept.
When relevant evidence is too advanced for the students in question, there should be a clear
acknowledgment of this difficulty, and a promise of relevant evidence at a later stage.
Where there are obvious theoretical alternatives, some of them historical, they should be
built into the presentation.
In addition, there should be a clear articulation of the value system of the discipline, to be
appealed to in the specific examples of argumentation at various stages.
Finally, there should be a clear sense of the fallibility and uncertainty of scientific
knowledge, as well as a sense of theoretical knowledge in science as a human creation. We
discover facts, but we invent scientific theories.
17
These ingredients should not be restricted to an introductory chapter in a textbook. They
should be woven as an integral part into every piece of knowledge: they should be included
in the syllabuses and textbooks, and tested in examinations.
Needless to say, the implementation of this suggestion would necessitate a major
reorganization of syllabuses and textbooks. At least for introductory courses, a number of
relatively non-basic topics in current syllabuses dealing with items of scientific knowledge
will have to be removed so as to make room for issues of evidence for the basic topics.
Suppose a textbook informs students that an atom consists of a nucleus and one or more
electrons, and that an atomic nucleus consists of one or more protons and optional neutrons.
Let us also suppose that constraints of time and space prevent the author from presenting
evidence for these hypotheses. A fruitful alternative would be to inform students that
scientists believe that an atom consists of a nucleus and one or more electrons, and proceed
to present the reasons for this belief, reserving hypotheses on the internal structure of
nuclei to an advanced course.
Ideally, discussion of evidence for scientific beliefs should be an essential component of
education for a primary school student as well as Ph.D. student. Critical thinking can
flourish only in an enlightened system of education that offers transparent knowledge and
critical understanding, so that the students are enabled to critically evaluate, question, and
modify the body of knowledge they receive.
I have argued above that critical understanding is a necessary condition for the
development of critical thinking and creative thinking in science. However, critical
understanding by itself is not sufficient guarantee for critical and creative thinking. We can
ensure a basic level of critical understanding by producing textbooks that present relevant
evidence for each piece of knowledge transmitted to students, and designing examinations
that test this aspect of knowledge. To develop the thinking skills, mere presentation of
evidence is not enough. To acquire thinking ability in science, students should do science,
which means performing tasks of the kind that scientists perform in their pursuit of science.
This means that the science classroom should have a workshop component where students
discover facts, construct theoretical explanations of facts, look for alternative explanations,
present evidence and argumentation in support of factual and theoretical claims, and
evaluate claims and arguments. In other words, the teaching of science will have to be
centered round a number of tasks aimed simultaneously at the development of scientific
knowledge and scientific thinking, rather than mere transmission of facts, theories, and
evidence. Incorporating critical understanding in textbooks and examinations would be the
first step towards this revolutionary approach to teaching science by making students do
science.
18
REFERENCES
Asimov, Isaac (1993) Atom: Journey across Subatomic Cosmos. Truman Talley Books.
Beardsley, Tim (1992) “Teaching Real Science.” Scientific American. October. p. 79-86.
Boden, Margaret (1992) The Creative Mind: Myths and Mechanisms. Abacus.
Cooper, Leon (1970) An Introduction to the Meaning and Structure of Physics. Harper and Row.
Detmer, Don E. (1997) “Science: A Mountain or a Stream.” Science. 28 March: p. 1859.
Einstein, Albert & Leopold Infeld (1935) The Evolution of Physics. Simon and Schuster.
Feynman, Richard (1963) The Feynman Lectures on Physics. Addison-Wesley Publishing.
————— (1965) The Character of Physical Law. The MIT Press.
————— (1988) “The Value of Science.” Public address at the 1955 autumn meeting of the
National Academy of Sciences, published in What do you Care what Other People Think?
Bantam Books (240–249).
Gardner, Howard (1983) Frames of the Mind: The Theory of Multiple Intelligences. Basic Books.
————— (1993) The Unschooled Mind: How Children Think and How Schools Should Teach.
Fontana Press.
Kuhn, Thomas (1970) The Structure of Scientific Revolutions. The University of Chicago Press.
McCloskey, Michael (1983) “Intuitive Physics.” Scientific American. April. p.114-122.
Pauling, Linus (1955) College Chemistry. W.H. Freeman and Company.
Ziman, John (1978) Reliable Knowledge. Cambridge University Press.
19
HOW DOES EDUCATION PARALYZE
INDEPENDENT THINKING?
CRITICAL UNDERSTANDING AND CRITICAL THINKING IN SCIENCE EDUCATION
K. P. Mohanan
Department of English Language and Literature
National University of Singapore
email: [email protected]
7TH INTERNATIONAL CONFERENCE ON THINKING
Singapore, 1 – 6 June 1997
20
TABLE OF CONTENTS
1. A Crisis in Science Education
2. Knowledge, Education, and Critical Thinking
2.1. Knowledge and Education
2.2. Transparent Knowledge
2.3. Critical Understanding
2.4. Critical Thinking
3. Levels of Understanding
4. Critical Understanding in Science: Fact vs. Theory
4.1. Factual and Theoretical Claims
4.2. Justifying Theoretical Claims
4.3. Fallibility of Scientific Knowledge
5. Levels of Critical Understanding
5.1. Representations
5.2. Theories
5.3. Conceptual Frameworks
5.4. The Value System
5.5. Critical Understanding and Independent Thinking
6. Science Education, Critical Understanding, and Critical Thinking
6.1. Absence of Critical Understanding in Science Education
6.2. Inhibition of Critical Thinking
6.3. Inhibition of Creative Thinking
7. A Possible Solution to the Crisis
References
21