used synonymously, but that really have two very different meanings. These different
visions are labeled as ‘‘science literacy’’ and ‘‘scientific literacy.’’ Science literacy, the
phrase used by the American Association for the Advancement of Science (1993) focuses
on the knowledge, processes, and products of science. Scientific literacy includes the
knowledge of science, but also extends to applications of this knowledge to make decisions
about personal and societal situations that have science and non-science components. The
purpose here is not to debate the relative merits of these two different visions. Indeed, the
vision focused upon in this paper is more aligned with scientific literacy as opposed to
science literacy.
Details aside, scientific literacy has always been at least partially associated with an
individual’s ability to make informed decisions about scientifically-based personal and
societal issues. However, meeting the stipulations of what it means to be scientifically
literate requires that an individual understand subject matter, nature of scientific knowledge
(NOS), and scientific inquiry (SI). In short, for an individual to make informed decisions
about scientifically-based issues he/she must be able to weigh the claims and evidence
against the characteristics inherent to scientific knowledge (NOS) and its development (SI).
Unfortunately, after over 60 years of research on nature of scientific knowledge (NOS)
there remains some confusion about the meaning of the construct. The situation, although
shorter-lived, is the same for scientific inquiry (SI). Consequently, it is important that a
clarification of these two important constructs be provided.
2 What Do We Mean by Nature of Scientific Knowledge (NOS)?
Before being specific about NOS, it is important to stress that we (my colleagues and
fellow researchers) are not advocating a definitive or universal definition of the construct.
We have never advocated that our ‘‘list’’ is the only list/definition. Unfortunately, readers
have read past our words (Lederman 2007; Matthews 2012; Irzik and Nola 2011) and think
we are stressing more than we are. Debates about a ‘‘definitive’’ description of NOS
abound, but are hardly productive. What we prefer readers to focus on are the understandings
we want students to have. The understandings need not be limited to those we
have selected, but we welcome discussions about whether our focus is scientifically,
developmentally, and educationally appropriate. The same is true for our discussion of
scientific inquiry that follows later. That said, let us begin to unpack the construct of NOS.
The phrase ‘‘nature of scientific knowledge’’ typically refers to characteristics of scientific
knowledge that are inherently derived from the manner in which it is produced, that
is scientific inquiry (Lederman 1992). Beyond these general characterizations, no consensus
presently exists among philosophers of science, historians of science, scientists, and
science educators on a specific definition for NOS. This lack of consensus, however, should
neither be disconcerting nor surprising given the multifaceted nature and complexity of the
scientific endeavor. Conceptions of NOS have changed throughout the development of
science and systematic thinking about science and are reflected in the ways the scientific
and science education communities have defined the phrase ‘‘nature of scientific knowledge’’
during the past 100 years (e.g., AAAS 1990, 1993; Center of Unified Science
Education 1974; Central Association of Science and Mathematics Teachers 1907; Klopfer
and Watson 1957; NSTA 1982). Indeed, during the 1980s the phrase ‘‘nature of scientific
knowledge’’ was shortened to ‘‘nature of science.’’ There is little doubt that this shift
in language introduced some confusion that continues today. Nature of science, in the
N. G. Lederman et al.
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research literature, refers to the nature of scientific knowledge and this is the definition that
is used in this paper.
It is our view, however, that many of the disagreements about the definition or meaning
of NOS that continue to exist among philosophers, historians, and science educators are
irrelevant to K-12 instruction. The issue of the existence of an objective reality as compared
to phenomenal realities is a case in point. While fodder for a lively discussion in a
philosophy of science class, it makes little sense to engage young science students in a
discussion of whether all observation is actually a function of human inference. We must
keep in mind the goal, which is to develop students’ understanding of the difference
between observation and inference and the implication for the development of scientific
knowledge. To this point, we argue that there is a developmentally appropriate level of
generality regarding NOS that is accessible to K-12 students and relevant to their daily
lives. Moreover, at this developmental level, little disagreement exists among philosophers,
historians, and science educators (American Association for the Advancement of
Science 1993; NRC 1996). Among the characteristics of the scientific enterprise corresponding
to this level of generality are that scientific knowledge is tentative (subject to
change), empirically-based (based on and/or derived from observations of the natural
world), subjective, necessarily involves human inference, imagination, and creativity
(involves the invention of explanations), and is socially and culturally embedded. Two
additional important aspects are the distinction between observations and inferences, and
the functions of, and relationships between scientific theories and laws. What follows is a
brief consideration of these characteristics of science and scientific knowledge.
First, students should be aware of the crucial distinction between observation and
inference. In the K-12 science classroom observations are presented as descriptive statements
about natural phenomena that are ‘‘directly’’ accessible to the senses (or extensions
of the senses) and about which several observers can reach consensus with relative ease.
For example, objects released above ground level tend to fall and hit the ground. By
contrast, inferences are presented as statements about phenomena that are not ‘‘directly’’
accessible to the senses. For example, objects tend to fall to the ground because of
‘‘gravity.’’ The notion of gravity is inferential in the sense that it can only be accessed
and/or measured through its manifestations or effects. Examples of such effects include
the perturbations in predicted planetary orbits due to inter-planetary ‘‘attractions,’’ and the
bending of light coming from the stars as its rays pass through the sun’s ‘‘gravitational’’
field.
Second, closely related to the distinction between observations and inferences is the
distinction between scientific laws and theories. Individuals often hold a simplistic, hierarchical
view of the relationship between theories and laws whereby theories become laws
depending on the availability of supporting evidence. It follows from this notion that
scientific laws have a higher status than scientific theories. Both notions, however, are
inappropriate because, among other things, theories and laws are different kinds of
knowledge and one cannot develop or be transformed into the other. Laws are statements
or descriptions of the relationships among observable phenomena. Boyle’s law, which
relates the pressure of a gas to its volume at a constant temperature, is a case in point.
Theories, by contrast, are inferred explanations for observable phenomena. The kinetic
molecular theory, which explains Boyle’s law, is one example. Moreover, theories are as
legitimate a product of science as laws. Scientists do not usually formulate theories in the
hope that 1 day they will acquire the status of ‘‘law.’’ Scientific theories, in their own right,
serve important roles, such as guiding investigations and generating new research problems
in addition to explaining relatively huge sets of seemingly unrelated observations in more