Van Huyssteen J.W. (editor) Encyclopedia of Science and Religion

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PHILOSOPHY OF SCIENCE

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of nature” (p. 26). One standard criticism that

Harding considers is whether there is such a thing

as a “feminist standpoint” that cuts across all

classes, races, and cultures.

Donna Haraway’s work Simians, Cyborgs, and

Women (1991) exemplifies the feminist postmod-

ernism tradition. Haraway rejects the idea of single

feminist standpoint and instead argues that all

knowledge is locally situated. Like Longino, Har-

away offers an alternative account of objectivity.

She writes, “Feminist objectivity is about limited lo-

cation and situated knowledge, not about tran-

scendence and splitting of subject and object. In

this way we might become answerable for what

we learn how to see” (p. 190). Although Haraway’s

view shares some affinities with social construc-

tivism, she explicitly rejects the label “relativist.”

She explains, “the alternative to relativism is not to-

talization and single vision. . . . [Rather, it is] partial,

locatable, critical knowledges. . . . Relativism is a

way of being nowhere while claiming to be every-

where equally. The ‘equality’ of positioning is a de-

nial of responsibility and critical enquiry” (p. 191).

Underlying many of these feminist philosophies is

a central concern for the social and ethical impli-

cations of science.

Scientific explanations and laws

The most influential account of scientific explana-

tion is Hempel’s covering law model. On this

model, explanations are understood as arguments

in which the explanandum (the event, feature, or

law to be explained) appears as the conclusion of

an argument. The premises of the argument must

contain at least one universal or statistical law used

essentially in the derivation, and empirically verifi-

able statements describing particular facts or initial

conditions. If the argument is deductive and in-

volves a universal law, it is called a deductive-

nomological explanation; if the argument is induc-

tive and involves a statistical law, then it is called

an inductive-statistical explanation. For example,

suppose one wants to understand why an ice

skater’s angular velocity increases as she draws her

arms in during a spin. The explanation would

show that this event can be logically deduced from

premises involving the law of conservation of an-

gular momentum and statements such as her initial

angular momentum was nonzero and her moment

of inertia was reduced by drawing her arms in.

Several philosophers and historians have ob-

jected that Hempel’s conditions are neither neces-

sary nor sufficient for a scientific explanation. The

most famous counterexamples fall into the cate-

gories of either irrelevance (although the event fol-

lows from the premises, as a matter of fact those

premises are irrelevant to the explanation of the

event) or symmetry (if the law involves a bicondi-

tional or equation then one can switch one of the

premises with the conclusion and “explain” things

such as why a flagpole is a certain height in terms

of the length of its shadow). These sorts of prob-

lems have led philosophers largely to abandon

Hempel’s model and propose new alternatives. To

handle the problems of irrelevance and symmetry,

Wesley Salmon (1925–2001) introduces a causal

model explanation, whereby to explain an event is

to identify the causes of that event. Alternatively,

van Fraassen in his pragmatic account of explana-

tion embraces the possibility that the length of a

shadow may explain the height of a pole. For van

Fraassen (1980), an explanation is always relative

to a particular context. Yet another model of ex-

planation is provided by Philip Kitcher (1981), who

understands explanation to be a unification of di-

verse phenomena by means of a common under-

lying structure or small number of processes. He

sees Charles Darwin’s theory of evolution as illus-

trating this model of explanation. The link between

explanation and unification is challenged by Mar-

garet Morrison in her book Unifying Scientific The-

ories (2000).

From reductionism to theoretical pluralism

Reductionism can be construed as a thesis about

ontologies, laws, theories, linguistic expressions,

or some combination of these. Considered as a re-

lationship between scientific theories, it can be

taken as a synchronic relation between two con-

current theories belonging to different levels of de-

scription or a diachronic relation between a histor-

ical predecessor theory and its successor. The

classic formulation of theory reduction is due to

the logical empiricist Ernest Nagel (1901–1985),

who takes it to involve the logical derivation of

one theory from another. More specifically, “a re-

duction is effected when the experimental laws of

the secondary science . . . are shown to be the log-

ical consequences of the theoretical assumptions

. . . of the primary science” (p. 352). The standard

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example is the reduction of thermodynamics (sec-

ondary science) to statistical mechanics (primary

science). In the physical sciences, reductionism is

more often taken to be a correspondence between

two theories under certain conditions, typically

characterized by the limit of some quantity. As

Thomas Nickles notes, this view is “best described

by ‘inverting’ the usual concept of reduction, so

that successors are said to reduce to their prede-

cessors . . . under limiting operations” (p. 181). For

example, special relativity is said to reduce to New-

tonian mechanics in the limit of small velocities.

Challenges to reductionism have come from

detailed case studies of the relations between par-

ticular scientific theories. One recurring challenge is

known as the problem of multiple realizability. For

example, in reducing Mendelian genetics to molec-

ular biology, as Alexander Rosenberg points out in

his 1989 “From Reductionism to Instrumental-

ism?”,one discovers that a single Mendelian trait can

be realized by a variety of molecular mechanisms,

and furthermore, the same molecular mechanism

can produce different Mendelian characteristics.

Another set of challenges arises when the reducing

theory is statistical (such as statistical mechanics or

quantum mechanics) and the reduced theory is not

as Lawrence Sklar indicates in this 1999 essay, “The

Reduction (?) of Thermal Dynamics to Statistical

Mechanics.” These sorts of difficulties have led

many to reject reductionism and instead argue for

theoretical pluralism, or the so-called disunity of

science. According to pluralism, each scientific the-

ory has its own proper domain of applicability. In

her book, The Dappled World (1999), Nancy

Cartwright raises the possibility that “nature is gov-

erned in different domains by different systems of

laws not necessarily related to each other in any

systematic or uniform way” (p. 31). This view has

been criticized on the grounds that it forfeits the

benefits that come from examining inter-theoretic

relations. The question of the unity or disunity of

science remains a controversial topic.

See also EXPLANATION; PHILOSOPHY OF SCIENCE,

ISTORY OF; POSITIVISM, LOGICAL

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ALISA BOKULICH

PHILOSOPHY OF SCIENCE,

ISTORY OF

In tracing the history of the philosophy of science,

it should be noted that philosophy and science

were not clearly distinguished from each other until

the early eighteenth century; furthermore, the phi-

losophy of science, as a distinct subdiscipline, did

not emerge until the nineteenth century. Nonethe-

less, almost from the beginning of philosophy, there

were thinkers who reflected on the methods, aims,

and epistemological status of inquiry into nature. In

this respect, Aristotle (384–322

B.C.E.) is generally

regarded as the first philosopher of science.

Ancient and medieval periods

Aristotle’s views on the philosophy of science are

primarily found in his Posterior Analytics. For Aris-

totle, genuine scientific knowledge has the status

of necessary truth. This necessity comes from the

fact that scientific explanations are to be demon-

strations—that is, logical deductions from premises

that are necessarily true. He argued that these

premises must function as “first principles,” which

are primitive (they cannot themselves be demon-

strated), known immediately, and known better

than the conclusions. Each science, whether it be

zoology or physics, has its own first principles.

Aristotle thought that we come to know these first

principles inductively through experience; that is,

we can intuit or perceive the essences of things in

our observations of nature.

In the Middle Ages, reflections on the scientific

method were primarily focused on elaborations

and criticisms of the views laid out in Aristotle’s

Posterior Analytics (which was reintroduced to

Western scholars in the twelfth century). In the

thirteenth and fourteenth centuries many scholars

began to call into question Aristotle’s assertion that

scientific knowledge is demonstrative—that it, has

the status of necessary truth. For many theologians,

this assertion seemed to be in conflict with the

doctrine of God’s omnipotence and with revelation

as the preeminent source of knowledge. The grow-

ing tension between Aristotelian natural philoso-

phy and church doctrine led the Bishop of Paris,

Etienne Tempier, in 1277 to issue a condemnation

of 219 propositions. Among these were proposi-

tions relating to Aristotle’s views that the world is

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eternal and that a vacuum is impossible. Both

Pierre Duhem and the contemporary historian of

science Edward Grant has argued that the con-

demnation of 1277 was an important stone in

paving the way, not only for the scientific revolu-

tion, but for new philosophical views about the

methods and epistemological status of science.

Early modern period

In 1620 Francis Bacon (1561–1626) published his

Novum Organum, or New Organon, in which he

laid out a new philosophy and methodology of sci-

ence that he hoped would replace Aristotle’s

Organon (the name given to the collection of Aris-

totle’s six books on logic and scientific method:

Categories, De Interpretatione, Prior Analytics, Pos-

terior Analytics, Topics, and Sophistical Refuta-

tions). Whereas Aristotle emphasizes deductions

from necessary first principles, Bacon emphasizes

induction as the central scientific method. Bacon

was not, however, a naïve inductivist: He notes

that impressions from the senses can be deceptive

and that it is a bad induction to infer the principles

of science through simple enumeration (Novum

Organum, Book I, Aphorism 69). Bacon famously

compares the proper scientist to a bee:

Those who have handled the sciences

have been either Empiricists or Rational-

ists. Empiricists, like ants, merely collect

things and use them. The Rationalists, like

spiders, spin webs out of themselves. The

middle way is that of the bee, which gath-

ers its materials from the flowers . . . but

then transforms and digests it by a power

of its own. (Novum Organum, Book I,

Aphorism 95)

Bacon is often referred to as the father of ex-

perimental science. Instead of simply observing

nature, Bacon advocates the use of experiments,

which are skillfully thought out and framed for the

purpose of inquiry. An important and controversial

legacy of Bacon’s philosophy of science is his no-

tion of a crucial experiment or “instance of the fin-

gerpost” (described in Aphorism 36 of Book II),

which is designed to unambiguously decide in

favor of one hypothesis or theory and refute

another.

Although René Descartes (1596–1650), like

Bacon, saw himself as providing a new epistemo-

logical foundation for science, in many respects

his views on science were a return to the Aris-

totelian ideal of science as a set of deductions from

necessary first principles. According to Descartes,

these first principles are known not through ob-

servations, but by the “light of nature” that is given

to us by God. Towards the end of his life, how-

ever, Descartes seemed to concede that this de-

ductive ideal is unattainable.

Descartes’s contemporary, Galileo Galilei

(1564–1642), blended a Baconian emphasis on ex-

perimentation with a Cartesian emphasis on the

importance of geometry for physics. In The Assayer

he famously claims:

Philosophy is written in this grand book,

the universe, which stands continually

open to our gaze. But the book cannot be

understood unless one first learns to com-

prehend the language and read the letters

in which it is composed. It is written in the

language of mathematics, and its charac-

ters are triangles, circles, and other geo-

metrical figures. (p. 238)

One of Galileo’s most important contributions

to the methodology of science is his use of ideal-

ization. As Ernan McMullin (1985) notes, Galileo

uses not only mathematical idealization, but also a

sort of causal idealization, whereby one considers

nature not in its full causal complexity but in an

idealized situation in which all but the causal line

of interest have been eliminated. Whether the con-

clusions drawn from these “artificial” scenarios

apply to nature in its full complexity as well was

an issue of debate between Galileo and the Aris-

totelian natural philosophers.

Scientific Revolution

In the generation following Descartes, Christian

Huygens (1629–1695) argues that the method of

science differs distinctly from that of geometry and

that the conclusions of science are, at best, highly

probable. In the preface to his Treatise on Light, he

argues for the hypothetico-deductive method in

science. According to this method one first puts

forward a hypothesis and then deduces from it cer-

tain observational predictions. If those predictions

are born out then the hypothesis is rendered more

probable.

Isaac Newton (1642–1727), by contrast, fa-

mously declared that hypotheses have no proper

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place in science—a declaration that was not en-

tirely consistent with his practice. In the General

Scholium to his Principia he writes, “I frame no hy-

potheses; . . . and hypotheses, whether metaphys-

ical or physical, whether of occult qualities or me-

chanical, have no place in experimental

philosophy” (p. 443). Instead, Newton advocates

the method of analysis and synthesis, which he de-

scribes in Query 31 at the end of his Opticks. Ac-

cording to this method one begins with “analysis,”

which consists of making observations and exper-

iments and then inductively drawing conclusions

from them. Once one has these inductive general-

izations in hand, the method of “synthesis” consists

in using them in turn to explain the phenomena.

Although Newton’s name is often associated with

the godless mechanistic worldview, Newton him-

self believed that blind necessity could not account

for the diversity in the world (General Scholium).

He furthermore believed that the uniform motions

of the planets required the intervening mainte-

nance of God. In Query 31 of the Opticks he writes:

For it became him who created them [all

material things] to set them in order. And

if he did so, it is unphilosophical to seek

for any other Origin of the World, or to

pretend that it might arise out of Chaos by

the mere Laws of nature. . . . [B]lind Fate

could never make all the Planets move

one and the same way in Orbs concen-

trick [sic]. (p. 402)

By the end of the eighteenth century an im-

portant shift had taken place, namely figures such

as Huygens and Newton realized that the empirical

sciences could at best yield probable knowledge;

the ideal of scientific knowledge as certain knowl-

edge came to be largely abandoned.

Early nineteenth century

In the early nineteenth century three important

books were published on the philosophy of sci-

ence: John Herschel’s A Preliminary Discourse on

the Study of Natural Philosophy (1830), William

Whewell’s The Philosophy of the Inductive Sciences,

Founded Upon Their History (1840), and John Stu-

art Mill’s System of Logic (1841). In Part I of his Dis-

course Herschel defends the study of natural phi-

losophy (science) against the charge that it leads

one to “doubt the immortality of the soul, and to

scoff at revealed religion,” arguing instead that it

leads to the betterment of one’s moral character

and undermines atheism (section 5). In Part II of

the Discourse he lays out three methods by which

one can come to discover scientific laws: first, by

inductive reasoning; second, “by forming at once a

bold hypothesis . . . and trying the truth of it by fol-

lowing out its consequences and comparing them

with facts” (section 210); and third, by a process

that combines both. With regard to the second (hy-

pothetico-deductive) method, Herschel notes

“when a theory will bear the test of such extensive

comparison, it matters little how it has been origi-

nal framed” (section 220). Passages such as this

have led the contemporary philosopher of science

John Losee to attribute to Herschel the invention of

the distinction between what Hans Reichenbach

(1891–1953) would later call the “context of dis-

covery” and the “context of justification.”

Whewell (1794–1866) was the first philosopher

of science to take the historical turn, arguing that

the philosophy of science ought to reflect—and

be a product of—a close historical examination of

the practice of science. Despite this important in-

sight, Whewell’s own philosophy of science was

probably to a greater extent shaped by the

philosophies of Bacon and Immanuel Kant

(1724–1804), than the history of science. Like Her-

schel, Whewell recognizes the important role that

hypotheses play in science, though he thinks that

these hypotheses are to be grounded inductively.

Whewell sees his work as a renovation of the in-

ductive method laid out in Bacon’s Novum Or-

ganum. The most striking renovation was

Whewell’s (Kantian) claim that the mind supplies

from within itself certain “fundamental ideas” that

shape, and are a necessary precondition for, expe-

rience and the empirical knowledge on which the

sciences are based. Whewell represents a surpris-

ing return to the claim that science aims for, and

can obtain, the status of necessary truth. The con-

temporary philosopher of science, Laura Snyder,

has cogently argued that these two aspects of

Whewell’s philosophy of science (fundamental

ideas and empirical science as necessary truths)

can be properly understood only in the context of

his natural theology. Snyder explains:

we are able to have knowledge of the

world because the Fundamental Ideas

which are used to organize our sciences

resemble the Ideas used by God in his

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creation of the physical world. . . . [T]he

Divine origin of both our Ideas and our

world is what enables Whewell to claim

that axioms knowable a priori from the

meanings of our Ideas are informative

about the empirical world, and necessarily

true of it. (p. 796)

In 1833 Whewell contributed his “Astronomy

and General Physics Considered with Reference to

Natural Theology” to the well-known Bridgewater

Treatises.

John Stuart Mill (1806–1873) debated Whewell

on the nature of induction in science. In Book II,

chapter 5 of his System of Logic Mill rejects

Whewell’s claim that science can obtain the status

of necessary truths. Mill writes:

I may have seen snow a hundred times

and may have seen that it was white, but

this cannot give me entire assurance even

that all snow is white, much less that snow

must be white. However many instances

we may have observed of the truth of a

proposition, there is nothing to assure us

that the next case shall not be an excep-

tion to the rule . . . experience cannot offer

the smallest ground for the necessity of a

proposition. (pp. 155–156)

Here it is clear that Mill is squarely in the em-

piricist tradition of David Hume (1711–1776) and is

construing induction narrowly as induction by sim-

ple enumeration. Mill’s best known contribution to

the philosophy of science is his four methods of

experimental inquiry (typically referred to as “Mill’s

Methods” though, as Losee and others have noted,

they can be found in the works of earlier medieval

natural philosophers) described in chapter 8 of

Book III of System of Logic. They can be summa-

rized as follows:

• Method of Agreement: If two or more in-

stances of the phenomenon have only one

circumstance in common, the circumstance

in which the instances agree is the cause of

the phenomenon.

• Method of Difference: If an instance when

the phenomenon under investigation occurs

and an instance in which it does not occur

have every circumstance in common save

one, then that circumstance by which they

differ is the cause (or an indispensable part

of the cause) of the phenomenon.

• Method of Residues: Subtract from any phe-

nomenon those parts that are known to be

the effect of certain antecedent causes; the

remaining part of the phenomenon (the

residue) is the result of the remaining an-

tecedents.

• Method of Concomitant Variations: Whatever

phenomenon varies when another phenom-

enon varies is either a cause, or an effect of

that phenomenon or is causally related to it

some way (e.g., both the product of a com-

mon cause).

Late nineteenth and early twentieth centuries

New challenges to the English inductivist tradition

came from the French physicist and historian of

science Pierre Duhem (1861–1916). Duhem argues

that physics is subject to certain methodological

limitations that do not affect other sciences. In his

book The Aim and Structure of Physical Theory

(1914) Duhem provides a devastating critique of

Baconian crucial experiments. According to

Duhem, an experiment in physics is not simply an

observation, but rather, is an interpretation involv-

ing a theoretical framework. Furthermore, no mat-

ter how well one constructs one’s experiment, it is

never a single hypothesis that faces an experimen-

tal test. Instead, it is a whole interlocking group of

hypotheses, background assumptions, and theo-

ries. This thesis has come to be known as holism.

According to Duhem, it is this holism that renders

crucial experiments impossible. More generally,

Duhem is critical of Newton’s description of the

method of physics as a firm and straight forward

“deduction” from facts and observations.

In the appendix to The Aim and Structure, en-

titled “Physics of a Believer,” Duhem draws out the

implications that he sees his philosophy of science

as having for those who argue that there is a con-

flict between physics and religion. He writes,

“metaphysical and religious doctrines are judg-

ments touching on objective reality, whereas the

principles of physical theory are propositions rela-

tive to certain mathematical signs stripped of all

objective existence. Since they do not have any

common term, these two sorts of judgments can

neither contradict nor agree with each other” (p.

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285). Nonetheless, Duhem argues that it is impor-

tant for the theologian or “metaphysician” to have

detailed knowledge of physical theory in order not

to make illegitimate use of it in speculations.

This separation of physics from metaphysics

that Duhem describes is characteristic of the posi-

tivist movement founded by Auguste Comte

(1798–1857) and developed by the Austrian physi-

cist and philosopher Ernst Mach (1838–1916).

Mach’s philosophy can be characterized as a form

of sensationalism, according to which the world

consists not of things, but sensations. In other

words, an object, such as an apple, is nothing but

a composite of various elements of sensations: red,

round, crunchy, and sweet; and talk about apples

is really just an economical way of talking about

collections of sensations. Indeed, all scientific the-

ories, for Mach, are just economical ways of talking

about sensations. Mach’s elements of sensation are

neither subjective, nor purely mental: Sensations

can also be considered physical in so far as they

depend in various ways on each other. Although

this view may be reminiscent of Bishop George

Berkeley’s (1685–1753) idealism (the view that

there are no material substances—only ideas and

the minds that contain them), Mach explicitly dis-

tinguishes his view from both Berkeley and Kant:

“Berkeley regards the ‘elements’ [of sensation] as

conditioned by an unknown cause external to

them (God); accordingly Kant, in order to appear

as a sober realist, invents the ‘thing-in-itself’;

whereas, on the view which I advocate, a depend-

ence of the ‘elements’ on one another is theoreti-

cally and practically all that is required” (pp.

361–362). Mach sees sensationalism as providing a

framework in which to unify the newly emerging

psychological sciences with the physical sciences.

Both progress and unification require eliminating

all concepts in physics that do not correspond di-

rectly to sensations (i.e., eliminating all metaphys-

ical concepts). On these grounds, Mach famously

denied atomism, which he took to be an unneces-

sary metaphysical assumption. Mach’s philoso-

phy—in particular, his rejection of metaphysics

and concern for the unity of science—greatly in-

fluenced the founders of the Vienna Circle.

Henri Poincaré (1854–1912) was a French

physicist, mathematician, and philosopher. In the

preface to his Science and Hypothesis (1902) he

distinguishes three kinds of hypotheses in science:

“some are verifiable, and when once confirmed by

experiment become truths of great fertility; . . .

others may be useful to us in fixing our ideas; and

finally, . . . others are hypotheses only in appear-

ance, and reduce to definitions or to conventions

in disguise” (p. xxii). It is his defense of this third

kind of “hypothesis” that makes Poincaré’s philos-

ophy of science a form of conventionalism. While

he does not think that all of science is a matter of

convention, he does take the geometry of space

and certain principles of mechanics to be simply

stipulated, rather than discovered. By saying that

something is conventional, Poincaré does not

mean that it is arbitrary—there are certain con-

straints and consequences that come with fixing a

convention. For example, although neither logic

nor experience forces us to accept Euclidean

geometry, rather than non-Euclidean geometry, as

the correct description of our space (i.e., it is a free

choice), choosing to adopt one geometry rather

than another will require us to adjust our physical

theories in certain ways (e.g., will require intro-

ducing new forces). Despite his conventionalism,

Poincaré adopts a realist stance toward science. He

writes, “we daily see what science is doing for us.

This could not be unless it taught us something

about reality; the aim of science is not things them-

selves . . . but the relations between things” (p.

xxiv). This has led some contemporary philoso-

phers to attribute to Poincaré the first expression of

a view known as structural realism. Poincaré con-

cludes the preface to his book by noting, “No

doubt at the outset theories seem unsound, and

the history of science shows us how ephemeral

they are; but they do not entirely perish, and of

each of them some traces still remain. It is these

traces which we must try to discover, because in

them and in them alone is the true reality” (p.

xxvi). While Poincaré’s remarks may or may not be

true of the history of science, they do seem to be

true of the history of philosophy of science.

See also PHILOSOPHY OF SCIENCE; SCIENCE AND

RELIGION, HISTORY OF FIELD

Bibliography

Aristotle. The Complete Works of Aristotle, Vol. 1, ed.

Jonathan Barnes. Princeton N.J.: Princeton University

Press, 1984.

Bacon, Francis. Novum Organum, With Other Parts of The

Great Instauration, ed. and trans. Peter Urbach and

John Gibson. Chicago: Open Court, 1994.

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PHYSICALISM,REDUCTIVE AND NONREDUCTIVE

— 662—

Descartes, René. The Philosophical Writings of Descartes,

Vol. 1, trans. John Cottingham, Robert Stoothoff, and

Dugald Murdoch. Cambridge, UK: Cambridge Univer-

sity Press, 1985.

Duhem, Pierre. The Aim and Structure of Physical Theory,

91914) trans. Philip Wiener. Princeton N.J.: Princeton

University Press, 1954.

Galileo Galilei. The Assayer, trans. Stillman Drake. In Dis-

coveries and Opinions of Galileo, ed. Stillman Drake.

New York: Anchor, 1957.

Grant, Edward. The Foundations of Modern Science in the

Middle Ages: Their Religious, Institutional, and Intel-

lectual Contexts. Cambridge, UK: Cambridge Univer-

sity Press, 1996.

Herschel, John. A Preliminary Discourse on the Study of

Natural Philosophy (1830). Chicago: University of

Chicago Press, 1987.

Huygens, Christiaan. Treatise on Light, trans. Silvanus

Thompson. Chicago: University of Chicago Press,

1945.

Laudan, Larry. “Theories of Scientific Method From Plato

to Mach: A Bibliographical Review.” History of Sci-

ence 7 (1968): 1–63.

Losee, John. A Historical Introduction to the Philosophy of

Science. Oxford: Oxford University Press, 1972.

Mach, Ernst. The Analysis of Sensations and the Relation of

the Physical to the Psychical (1897), trans. C.

Williams. New York: Dover, 1959.

McMullin, Ernan. “Galilean Idealization.” Studies in the

History and Philosophy of Science 16, no. 3 (1985):

247–273.

McMullin, Ernan. “The Development of Philosophy of Sci-

ence, 1600–1900.” In Companion to the History of

Modern Science, ed. Robert Olby, G. Cantor, J.

Christie, and M. Hodge. London: Routledge, 1990.

Mill, John Stuart. System of Logic Ratiocinative and Induc-

tive: Being a Connected View of The Principles of Evi-

dence and the Methods of Scientific Investigation,

(1841). New York: Harper, 1846.

Newton, Issac. The Principia (1687), trans. Andrew Motte.

Amherst, N.Y.: Prometheus, 1995.

Newton, Issac. Opticks: or A Treatise of the Reflections, Re-

fractions, Inflections and Colours of Light (1704).

New York: Dover, 1952.

Poincaré, Henri. Science and Hypothesis (1902). New

York: Dover, 1952.

Reichenbach, Hans. Experience and Prediction: An Analy-

sis of the Foundations and Structure of Knowledge.

Chicago: University of Chicago Press, 1938.

Snyder, Laura. “It’s All Necessarily So: William Whewell on

Scientific Truth.” Studies in History and Philosophy of

Science 25, no. 5 (1994): 785–807.

Whewell, William. The Philosophy of the Inductive Sci-

ences, Founded Upon Their History. London: J.

Parker, 1840.

ALISA BOKULICH

PHYSICALISM,REDUCTIVE

AND

NONREDUCTIVE

Physicalism is a doctrine that asserts that ultimately

only physical particulars exist. While physicalism

and materialism are sometimes considered equiva-

lent, the former is more ontologically open, for

while materialism claims that everything is com-

posed of matter, physicalism holds that everything

is comprised ultimately of those entities assumed

in the basic statements of fundamental physical

theory (fields, particles, strings, or whatever). The

thesis that only these physical entities exist is often

termed ontological physicalism.

While ontological physicalism is often presup-

posed in the philosophical discussion, controversy

arises about the properties possessed by these

physical particulars. For example, what is the on-

tological status of putative mental properties? Are

they reducible to underlying physical properties, or

do they have a kind of being of their own? The re-

ductive physicalist affirms, while the nonreductive

physicalist denies, that mental properties are “noth-

ing but” the physical. Broadly conceived, reductive

physicalism asserts that all nonphysical properties

are coextensive with particular physical properties.

Nonreductive physicalism, on the other hand, con-

joins the irreducibility of nonphysical properties

(property dualism) to ontological physicalism.

Since the 1960s considerable doubt has been

cast on the reductive physicalist project. In Ernest

Nagel’s (1901–1985) classic account, physicalist re-

duction occurs when nonphysical predicates are

biconditionally connected to particular physical

predicates such that the nonphysical property is

instantiated when and only when a particular phys-

ical property is instantiated, (e.g., the mental prop-

erty of a particular headache pain is instantiated

when and only when a particular neuro-property

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is). However, one can imagine a silicon-based Mar-

tian having the same headache pain as an earth-

ling, but because of the Martian’s different neuro-

physiology, different physical properties will be

instantiated. Because the same mental state seems

to be realizable in different physical systems, re-

ductive physicalism is called into question. Conse-

quently, nonreductive physicalism has generally

replaced reductive physicalism in the philosophy

of mind. Accordingly, while the instantiation of an

upper-level mental property is not reducible to the

instantiation of a lower-level one, it is nonetheless

realized by some lower-level property. Thus, in-

stead of a type identity between property kinds,

(every time mental property m is instantiated,

physical property p is instantiated), there is a token

identity between an instantiation of m and the in-

stantiation of some physical property or other.

Issues of reductive and nonreductive physical-

ism are important in the science/theology discus-

sion. If, as the natural sciences methodologically

assume, only physical entities have causal powers

and hence ultimately exist, then what kind of sense

can be made of religion and its talk of God? In re-

sponding to this problem, nonreductive physical-

ism seems initially promising, for it holds with the

natural sciences that only physical entities exist,

and yet agrees with religion in claiming that there

are irreducible nonphysical properties. If it can be

shown that our mental life is irreducible to neuro-

science, then insofar as religion concerns our men-

tal life, it too is irreducible to the physical.

But large questions loom. Can upper-level

properties be something more than mere epiphe-

nomena, if they are token identical to physical

properties that do all the causal work? Alternately,

if physical properties do not do all the causal

work, can dualism be avoided? Finally, if the irre-

ducible mental is nonetheless completely realized

by the physical, then in charting this physical real-

ization, is one not offering a reductive explanation

of the mental, and its religious experience, after all?

See also MATERIALISM; MIND-BRAIN INTERACTION;

ATURALISM; REDUCTIONISM; SUPERVENIENCE

Bibliography

Beckermann, Ansgar. “Introduction—Reduction and

Nonreductive Physicalism.” In Emergence or Reduc-

tion? Essays on the Prospects of Nonreductive Physi-

calism, eds. Ansgar Beckermann, Hans Flohr, and

Jaegwon Kim. Berlin and New York: Walter de

Gruyter, 1992.

Davidson, Donald. “Mental Events.” In Essays on Actions &

Events. Oxford: Clarendon Press, 1980.

Kim, Jaegwon. Mind in a Physical World: An Essay on the

Mind-Body Problem and Mental Causation. Cam-

bridge, Mass.: MIT Press, 1999.

Murphy, Nancey. “Physicalism without Reduction: Toward

a Scientifically, Philosophically, and Theologically

Sound Portrait of Human Nature.” Zygon 34 (1999):

551-572.

Nagel, Ernest. The Structure of Science: Problems in the

Logic of Scientific Explanation. New York: Harcourt,

Brace, and World, 1961.

DENNIS BIELFELDT

PHYSICS

Physics is the branch of scientific investigation that

focuses its attention on fundamental concepts, pat-

terns, and relationships involving matter, energy,

space, and time. Other natural sciences, such as

chemistry, biology, geology, and astronomy, also

deal with these categories in their investigation of

material systems like atoms, molecules, life

processes, organisms, planets, stars, and galaxies,

but physics is concerned with the most basic and

universal principles that apply to all of these di-

verse systems.

It is sometimes convenient to divide physics

into several different arenas of concern, such as

mechanics (the study of motion), electromagnet-

ism and optics, thermodynamics, quantum

physics, atomic physics, nuclear physics, particle

physics, and relativity (the study of space, time,

and gravity).

Classical mechanics is the study of motion in

the manner established by Isaac Newton in the

seventeenth century. Among its major contribu-

tions is a fruitful method for describing the cause-

effect relationship for motion in a quantifiable

manner. A force, like the familiar push or pull,

functions as the cause of acceleration (any change

in the speed or direction of motion), which is its

effect. Another major contribution of Newton was

his concept and description of the force of gravity

that is experienced and exerted by every object

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possessing the quality of mass. The gravitational

force that causes apples to fall earthward is also

the kind of kind of force that steers the moon in its

orbit around the Earth and the planets in their or-

bits around the sun.

Electromagnetism encompasses all phenom-

ena in which electric and magnetic fields play a

role. In classical physics, fields may be thought of

as qualities of space that lead objects with certain

properties to experience a force. Any object pos-

sessing the property of electric charge, for exam-

ple, will experience a force in the presence of an

electric field. Electromagnetic radiation (light,

X-rays, radio waves) may be understood as varia-

tions in electric and magnetic fields that travel at

the characteristic speed of three hundred thousand

meters per second through space.

Thermodynamics is concerned with the man-

ner in which energy, especially heat energy, af-

fects the state of a system and its interaction with

its environment. Energy, often characterized as the

capacity to do work, appears in a diversity of

forms and may be changed in either form or loca-

tion as a consequence of some physical process. In

all processes, however, the sum of the energy pos-

sessed by a system and its environment remains

constant. This principle, called the First Law of

Thermodynamics, or the conservation of energy, is

thought to apply without exception to all physical

phenomena.

Quantum theory describes the structure and

behavior of systems like atoms, atomic nuclei, and

molecules. Extremely small structures behave in a

manner different from the predictions of classical

mechanics. The quantities of energy possessed by

a system or exchanged between systems, for in-

stance, is restricted to certain values only. Further-

more, the outcome of many processes is open to

diverse options, each outcome having a calculable

probability of occurrence.

Relativity theory provides a framework for

speaking of the interactive relationships among

space, time, mass, and gravity. Special Relativity

describes the way in which the experience of time

and space are interrelated, while General Relativity

focuses its attention on the interrelationships

among mass, space, gravity, and motion.