You're about to embark on a journey of discovery. You'll be learning a lot, asking numerous questions, and exploring the culture of "real" science. Before beginning, however, I think it would be wise to examine some important issues -- broad, general matters that have to do with making judgements about what you're going to learn. For example:
Here are a few questions that may help you determine why you believe somethings and not others.
It's obvious, even from the brief list of questions presented above, that all of us have to regularly decide the truth of a great number of matters. These decisions fall into certain categories.
In many cases, we are told "facts" in school or by others about past or ongoing matters ("Washington was the first president", "Air consists of a mixture of gases"), explanations ("Drinking alcohol to excess interferes with good judgment"), and what will happen ("There will be an solar eclipse in Hawaii on December 12, 2002") that we are expected to believe. Why should we accept them? We are told to believe in some things and not others by our parents or religious leaders or scientists or politicians. How do they know? In some cases, we decide on the truth of falsehood of some issues because of input from our friends or from commentators on TV. Sometimes we decide things because we have a "gut" feeling about them. Thus the crucial question: How should we decide what is true or what to believe?
It is clear that it would be nice to have some help in deciding whether to believe a suggested explanation or fact. Having a list of rules would certainly make it easier to determine whether to believe what politicians, teachers, clergy, philosophers, and scientists tell you. Here are a few guidelines. (Let me say up front that following these suggestions never guarantees the truth.) After each quideline, I've included a paragraph indicating how "Science" uses these indicators to decide about the truth or falsity of something.
Objectivity
When a tobacco company executive asserts that smoking doesn't
cause cancer, you may feel that he may not be telling the truth
because his livelihood depends on the sales of cigarettes. When a
politician denies involvement in a scandal, most of us keep in mind
that his political interests don't make him an impartial party. Thus
the general principle: We tend to believe people who do not have a
stake in a decision. (In some courtrooms, the outcome of some cases
is determined by an impartial observer, the judge. In others, a jury
may play the same role. In both instances, the evidence is presented
by advocates for opposing sides - who do have a stake -
but each side is supposed to have an equal chance to present their
point of view.) But be careful: Just because people have a stake in
the outcome of some dispute doesn't mean that they are inaccurate or
wrong. And similarly, impartial judges and juries make mistakes too.
In Science, objectivity is treated in a funny manner (funny peculiar, not funny humorous). The proponent of a point of view is supposed to be impartial. Certainly the entire scientific process depends on the fact that scientists aren't supposed to cheat or distort their data. They have to play by the rules. At the same time, scientists are supposed to act as advocates, advancing and even pushing their ideas. Generally, the scientific community also understands that someone who is advancing some idea is not the best person to look to for debunking that idea. And, it turns out that high status is given to those who are able to devise ways of showing that someone else's ideas are wrong.
Consensus
We tend to believe things when there is near uniformity or at
least a consensus among those asserting something. The great majority
of scientists, for example, believe that AIDS is caused by the HIV
virus -- even though there are a few prominent exceptions. Many
scientists think that mad cows disease (Bovine spongiform
encephalopathy or BSE) is caused by an infectious agent that contains
no RNA or DNA. But there is a segment of the scientific
community that thinks otherwise. However, keep in mind that
experience has shown that the majority isn't always correct. In fact,
there have been many points in history -- in science and in other
matters -- where there was a near unanimity of view among a group,
and that view was wrong.
In Science, the "facts" that we read in textbooks appear to derive from a consensus view of the scientific community. In other words, most of what you learn in school is what most scientists believe to be true. But how is this consensus evaluated? How is it known what the concensus thinks? There aren't votes. There almost never is a tabulation of numbers on either side of an issue. The fact is that scientific consensus comes from about in an informal manner (see "How Science works", below).
Status
There is a tendency to believe something if the person or
institution who asserts it has a high status because of something
he/she/they has accomplished, or because that person is presumably an
expert in an area, having devoted their lives to studying a subject.
The Nobel Prize winner is often given much more credibility than Joe
Blow; the New York Times is believed more often than the World News.
Advertisers recognize this tendency in humans by paying sports stars
and political figures to appear in their commercials. Presumably,
their status lends credence to their advocacy of some position or their endorsement of some product. There
are two things to keep in mind here: Even experts are often wrong,
and expertise in one field often doesn't carry over to another.
Simplicity
The principle of Occam's Razor (formulated in the middle ages)
says that if there are two equally good explanations that account for
all the facts concerning some phenomenon, than the simpler one is the
better (although, of course, both may be wrong!). Another way of putting it is
that one can explain anything if you add enough "ifs" to an
explanation.
In Science, Occams Razor also holds. On the other hand, the real world is complicated and some phenomena require complicated explanations. This is particularly true of biology.
Reproducibility
One of the problems with demonstrating the existence of
extrasensory perception is that people claim that it is a power that
occurs occasionally, and that it doesn't work in a controlled
setting. On the other hand, if some phenomenon occurs repeatedly or
if you can get it to occur regularly under certain specific conditions, then
you have more confidence that it is real. So, when dealing with
phenomena that are occurring in the present, an important component
of believability is to get it to happen regularly under the same
conditions. If you take a ball and raise it to waist height and then
release it, it may fall straight down (more or less) with a certain
velocity and acceleration. If it behaves the same way after 100
tries, then you tend to believe that the phenomenon is real and will
occur on the 101st try.
Reproducibility is a key principle in Science. If you do toss a coin twice and it comes up heads each time, that doesn't mean that the coin isn't true. If you tossed the same coin 1000 times and each time it came up heads, you'd have much more confidence that heads was favored. However, just because it happened every time before, that doesn't guarantee that it will happen the same way next time. In fact, there's no logical reason to believe that phenomena have to be repeatable, or that something that repeats will continue to do so.
Accuracy and specificity
We tend to believe that Newton's laws of physics are true under
most conditions because they can very accurately predict things like
tides, eclipses, and the path of rockets with amazing accuracy.
Or, put another way, if Jeanne Dixon (a popular "seer" in the mass
media) were to make her predictions more accurate ("On July 15, 2001,
Michael Jackson will run away with Julia Roberts"), then one will have a
tendency to believe in her more strongly when they occur. Predictions
that aren't very specific ("There will be large earthquake in North
America in the decade of the '00's") don't have as much weight. And
of course, track records count. If one is mostly wrong, one tends not
to be believed.
But again, in Science as in everything else, being right even 100% of the time in the past doesn't guarantee that you will be right the next time. And being wrong previously, doesn't mean that you won't be right the next time.
Demonstrability
While your eyes and other senses can be fooled by illusions of
various sorts, most people put much stock in what their senses
perceive. In fact, a whole state (Missouri) seems to think that
seeing is believing. Similarly, those instruments that extend our
senses and either increase their range or accuracy:
microscopes, telescopes, voltmeters, photometers, also
support our beliefs. However, some ideas about the real world aren't readily tested. Historical
events can't be repeated (the Big Bang, evolution of dinosaurs), so
how can one test whether they're right? Yet we believe many
historical truths, even if we weren't alive to see them for
ourselves. In general, if an idea is testable -- you can set up a way
of demonstrating that it will be either right or wrong -- then
that idea is often more worth considering than one that is not.
On the other hand, our senses can deceive us, particularly when we're not prepared for something new. There are some great precedents for this in Science. The great Italian physicist Galileo (1564-1642) looked at the planet Saturn and saw three spheres, rather than rings.
Not contradictory, logical
It is difficult to hold two beliefs at the same time that are
contradictory to one another. One tends to believe ideas and theories
that augment or buttress ones that you already hold. If you believe
fact A because it is supported by facts B, C, and D; and if
observation E comes along that is in support of A, B, C and D, then
you tend to believe E.
On the other hand, what seems logical to one person may not be logical to another. For example, there are phenomena in quantum physics that don't seem to make any sense. Yet quantum physics seems to work very well. Science deals primarily with what works, and if forced to, will disregard logic when necessary.
Alternate views
The more different ways that one test ideas and the more that they
continue to give a consistent picture, the more confidence we have
that they're right.
Science is concerned with understanding of the real world. It works best when confronting phenomena that are happening now and are subject to manipulation (the path that a bullet takes when fired from a gun; how cells divide; the presence of certain subatomic particles). It doesn't always work so well -- but still is reasonably effective -- when dealing with historical events (how mountains formed; how life arose; the big bang) or phenomena that are out of reach (life on other planets, the birth of a star). It's been particularly unsuccessful in dealing with matters concerning morality or ethics or motives.
Science finds out about the real world by using all the indicators of truth mentioned above and then engaging in a communal activity. In other words, Science can't be carried out in isolation. Typically, a scientist (or group of scientists) works on some question or finds some new phenomenon. After satisfying themselves that they have found something new (in general, finding out something that someone has already discovered is uninteresting to scientists. I'll have more to say about this later), they submit their findings to the community. This may take the form of an informal remark to a colleague, a seminar or poster session directed at a group of colleagues, or a formally published article. The last route, formal publication in a scientific journal, is the official route for community dissemination. It is vital to the scientific process, and the maxim "publish or perish" is deeply rooted in the scientific method.
Publication
The act of publication is saying that the scientists think that
they have discovered something new and they are announcing this to
the science community. At the same time, they are trying to convince
the community that they are correct; that they haven't made any
mistakes in their observations or methods, that what they've found is
significant. What many nonscientists don't understand is that all
good scientific journals (that is, magazines in which articles are
published) carefully evaluate submitted articles, and often don't
accept more than a few percent. All journals have one or more
editors. They send the article out for review, a process where one
more colleagues carefully evaluate the article and decide whether it
is likely to be correct, whether it is noteworthy, whether there is
enough evidence in support of the assertions made in the article, and
whether it fits with the philosophy and interest of the journal.
Mistakes can be (and often are) made, after all, Science is a human activity. Sometimes an article is rejected, even though it is important and correct. Sometimes articles are accepted that have errors in them or are completely wrong (or even fabricated). If an article contains errors, several things may happen. Sometimes the facts in an article are checked by another group of scientists who then come up with a different story. Sometimes, the authors of the article find that they have made a mistake and they publish a retraction. Sometimes no one pays attention and the article gets forgotten.
Sometimes another group of scientist assumes the mistaken data is correct, and builds on it, thereby reinforcing the error. Since Science is supposed to explain the real world, and since the real world seems to consist of a set of interlocking phenomena, a mistake in one place can affect the interpretation in many other places. Ultimately, mistakes are supposed to be caught, and Science is said to be self correcting.
An interesting question is who decides what is correct? After all, even after all these criteria, there still may be conflicting opinions. Is there a scientific supreme court? a Pope? a Bible? How do people know what should go into textbooks and what shouldn't?
The answer is that somehow scientists make a collective decision. Writers of textbooks and teachers take the findings that are published, especially those that are not in dispute and that many scientists seem to agree on and that fit in neatly with other findings, and put these into their textbooks. These findings then become "facts". And it is these "facts" that you will be learning. But because every scientist doesn't have to hold to them, these decisions aren't written in stone. In fact, because new facts emerge at regular intervals, what the scientific community believed yesterday may not be what it believes today or what it will believe tomorrow.
