What is Science?

Etymology, history and epistemology

Linguistic issues• ‘Scientia’ is a Latin word, meaning knowledge. • ‘Science’ came to be used (with the same meaning) in old French. • This notion was originally much broader in scope than our present

use of science– it included all kinds of knowledge. • The use of ‘science’ as a special term for study of the natural world

is relatively recent. • Newton’s chair is a chair in natural philosophy, which was the

standard term for some subjects we would call sciences including physics and chemistry today.

• The sciences we now call biology and geology were then called natural history.

• These phrases persisted well into the 18th century; in the 19th century the growing professionalization of science and its separation from other forms of knowledge led to the term as we now use it.

Knowledge• This has been a term of art in philosophy from its very

beginnings. • To know something is, first, to be right about it; this

applies both to knowledge of how to do something (where the proof is in the practice) and to knowledge of fact (where the proof is in the evidence).

• With some caveats (which arise in peculiar cases) knowledge of fact can be thought of as adequately justified true belief.

• But this doesn’t explain much without more details on what we mean by adequate justification (not to mention truth).

Evidence and truth• These are central ideas in our understanding of knowledge. • Justifying our beliefs requires that we give real evidence in support of

them (not that we give this much thought most of the time). • What counts as evidence is related to our notion of truth– for it to be

proper evidence, it must (in some sense) support (i.e. be something from which we can, if only tentatively and conditionally, infer) the truth of the claim it’s evidence for.

• We can ignore the subtleties of different philosophical theories of truth so long as we accept a condition that Alfred Tarski claimed all such theories must meet:

• Where ‘X’ is the name of a sentence that we abbreviate the sentence by writing p,

X is true if and only if p. • Given this, we can infer the truth of X from anything we can infer X from–

so we can (for now) focus on basic sentences and evidence for them without worrying about what ‘truth’ is.

World View• Science as we know it today is the source of a particular description of the world

and of ourselves. Many aspects of this world view are (or at least were) wildly counter-intuitive when they were first proposed.

• At one extreme, there is Galileo’s defense of the idea that the earth is turning (rather than the rest of the universe spinning about us): People asked, in response, why does an object dropped from a tower land at the base of the tower rather than far away as the earth turns under it? The motion of the object, on Galileo’s account, is clearly not a vertical motion towards the earth’s centre!

• At the other extreme, we have today’s quantum physics, which allows the state of an object to be definitely located among some collection of states while definitely not in any one state belonging to that collection.

• Further, it holds that we are descended from a distant common ancestor shared by all life on earth.

• This scientific world view is always tentative and subject to change: despite its many brilliant successes, classical (Newtonian) mechanics has been given over for general relativity (on the large scale) and quantum mechanics (on the small). In the early 1960’s the idea that the continents have always been where they now are was overturned by plate tectonics, which holds that the continents have wandered the earth, joining together and splitting apart many times.

World view stuff

A crude image of an atom An image of the universe

The development of science• The history of the development of this world view

occurred, for the most part, in Western Europe.• In this sense, it’s the product of a particular culture. • This leads some to emphasize that science is only ‘one way

of knowing’, one among many different cultural practices for arriving at descriptions of the world.

• But it has become a widely-accepted practice among many other cultures as well—science has spread in ways that (for example) the Azande practice of the ‘poison-oracle’ has not.

• The spread of science might be partly explained as due to ‘cultural imperialism’.

• But it’s pretty clear that this is not explanation enough.

The tree of life

Plate tectonics

The earth’s motion

Successful Practices• One bit of history that’s worth relating here is the story of Greek

medicine and Arab conquerors.• Following the conquest of the eastern Mediterranean, Arab

physicians soon realized that the Greeks could successfully treat some conditions that they could not.

• They responded by studying and translating Greek medical practices and writings, adopting them and making them their own.

• So in this case it was the reverse of cultural imperialism: The conquerors adopted both the successful practice of the conquered and the theoretical framework in which that practice was embedded.

• These texts and practices were later transferred from Arab regions to Europe, along with Greek scientific and philosophical works (most influentially, those of Aristotle).

Standards of success

• This case (and plenty of others) suggests that the standards by which we judge whether or not a practice works are at least partly independent from the framework of other ideas in terms of which we understand the practice.

• This contrast between the place of a practice within a system of ideas and its place in the world is an important aspect of empiricism: the view that experience is the sole source of substantial, matter-of-fact knowledge.

Authority• The source and scope of science’s authority are important questions here.

– On what grounds does science offer up this strange but powerful view of our world and ourselves?

– To whose allegiance does this world view lay claim?• The empiricist response to the first is that the evidence on which the

scientific world view is based is, in the end, a matter of experience. (This leaves many questions about the nature of experience and how it comes to provide evidence for science—or for anything else– open.)

• The empiricist response to the second claims a kind of universality for science. While nothing requires that we all understand our experience in the same way, we do all have experience, and our basic sensory capacities are much the same.

• This is supported by the observation that the most straightforwardly translatable and independently testable aspects of language use have to do with describing the objects around us in terms of their sensible characteristics; the justification of scientific claims begins with observations of the world expressed in these terms.

Anthropocentrism• This starting point for science is not tied to any single

culture, and the kinds of tests we want scientific theories to pass are not arbitrary, culturally dependent values either (anymore than the basic goals of medical practice are) but tests that any reliable, useful sort of description should pass.

• Still, the fact that it begins with how humans naturally describe the sensible world around them makes our starting point anthropocentric.

• One of the central questions about scientific realism is whether this initial anthropocentrism is something we can escape as scientific investigation continues, or whether we are stuck with an anthropocentric view of the world.

Reducing anthropocentrism• One sort of anthropocentric aspect of our world view involves colour, smell, taste,

the ‘feel’ of hot and cold. These ‘proper sensibles’ divide the world’s objects up into categories (groupings) that depend on the details of our sensory apparatus. (For example, the taste of aspartame is a lot like the taste of sugar– but they are chemically quite different…)

• Philosophers since Descartes have argued that these aspects of our world view are not part of a scientific description of the world– but it’s hard to imagine actually eliminating them in practice!

• Another important anthropocentricism has to do with how difficult it is (and how long it took) to appreciate that the earth is moving, and that the entire universe does not revolve around us once every day.

• This second anthropocentrism is one that we have eliminated for serious purposes (since Copernicus, or, to be more historical, since Galileo and Kepler). Though we still casually describe the sun as ‘rising’ and ‘setting’, we know perfectly well that what’s actually going on is the earth turning.

• Other anthropocentrisms appear in our particular systems of measurement (the meter, the kilogram etc.)– but the role of these in our physical descriptions is really inessential: they are handy, but the real facts (ratios of actual distances, masses etc.) don’t involve these units at all.

Still less anthropocentrism• Einstein’s special and general theories of relativity also aim to remove

anthropocentric elements from our description of the world. • The special theory of relativity is founded on the postulate that the speed

of light is constant for all observers, no matter what their state of motion is– as a result, many things (including the length of objects and the time that passes between two events) turn out to depend on one’s point of view, and a new account of things in terms of what does not depend on point of view is developed.

• The general theory of relativity is founded on the postulate that inertia and gravity are indistinguishable (at least locally); the upshot is that the geometry of space-time is also a matter of ‘point of view’ rather than an objective feature of the world.

• We’ve also made progress towards explaining how our visual system manages to assign stable colours to objects that we see; at this point the story is pretty complete, from the sensitivity of different kinds of ‘cone’ receptors in the retina to the visual processing centres of the brain; the operations of taste and smell receptors are also pretty well understood.

So how does this work?• How do we sort out anthropocentric features of the world from its

more objective features?• I want to suggest today (I’ll do no more, really, than that) that the

key to this process is explanatory coherence, that is, making our observations fit together in an inferentially tidy way.

• Consider how this applies to how we use an objective description of the locations and shapes of objects around us to explain how they appear to observers located in different places.

• Similarly, our eyes, retinal receptors and neural system, along with the surface reflectance properties of objects provide the basic components in an explanation of why things appear to have ‘surface’ colours to us. (Other types of colour– iridescence, the colour of the sky etc. can also be explained in closely related ways.)

• In general, the objective story of things should explain how things appear, from various places and for different types of organism.

A bit of history

• Philosophy of science is a pretty recent specialization.• Some interesting figures wrote about these issues in

the 19th century. (Whewell, Herschel, Mach, Compte and others…the notion of a vera causa, discussed by Herschel in particular, was quite important to Darwin)

• But we’ll be concentrating on the 20th century and the present situation in the field.

• The idea will be to get a broad sense of the developments that led to the present state of the field, and then to explore some of the main issues that philosophers of science are concerned with today.