If anyone uses thermodynamics against evolution, they're an idiot anyway:

Entropy and Life- The Functions of Thermodynamics and their implications for biological systems

And, to paraphrase him, don't tell me I'm wrong about this, as I studied it to doctorate level.

This is probably this best defintion that I have for Law, Hypothesis and Theory in the scientific field.

Scientific Law: This is a statement of fact meant to explain, in concise terms, an action or set of actions. It is generally accepted to be true and univseral, and can sometimes be expressed in terms of a single mathematical equation. Scientific laws are similar to mathematical postulates. They don’t really need any complex external proofs; they are accepted at face value based upon the fact that they have always been observed to be true.

Specifically, scientific laws must be simple, true, universal, and absolute. They represent the cornerstone of scientific discovery, because if a law ever did not apply, then all science based upon that law would collapse.

Some scientific laws, or laws of nature, include the law of gravity, Newton's laws of motion, the laws of thermodynamics, Boyle's law of gases, the law of conservation of mass and energy, and Hook’s law of elasticity.

    Hypothesis: This is an educated guess based upon observation. It is a rational explanation of a single event or phenomenon based upon what is observed, but which has not been proved. Most hypotheses can be supported or refuted by experimentation or continued observation.

Theory: A theory is more like a scientific law than a hypothesis. A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers. One scientist cannot create a theory; he can only create a hypothesis.

In general, both a scientific theory and a scientific law are accepted to be true by the scientific community as a whole. Both are used to make predictions of events. Both are used to advance technology.

In fact, some laws, such as the law of gravity, can also be theories when taken more generally. The law of gravity is expressed as a single mathematical expression and is presumed to be true all over the universe and all through time. Without such an assumption, we can do no science based on gravity's effects. But from the law, we derived Einstein's General Theory of Relativity in which gravity plays a crucial role. The basic law is intact, but the theory expands it to include various and complex situations involving space and time.

The biggest difference between a law and a theory is that a theory is much more complex and dynamic. A law governs a single action, whereas a theory explains an entire group of related phenomena.

    This of course is the major difference between theory and law, but those not in the know cannot tell the difference between scientific theory and just regular everyday layman theory, which is where the big confusion occurs. 

Seeing as I'm also no expert, here's the soundbite version as it was explained to me: "a law tells you WHAT will happen; a theory tells you WHY". I don't mean "why" in a sense to ascibe meaning to things; atoms really don't give a damn about what we want to be true.

Laws: gravitation, equal motion, 2nd thermodynamic all explain that given set of circumstances A will result in situation B. When you think "scientific law", think "equation". Laws predict future outcome given a starting state.

Theories: germ, relativity, number all explain WHY we get sick, the matter's maximum velocity and why prime numbers are the basis for all mathematics. Theories are collections of interacting laws and hypotheses that explain the actions of complex systems.

If I'm wrong about any of the above, someone please correct me.

I always have the issue when debating with friends, they will say evolution is just a theory. I always tell them a theory is supported by various facts and emperical evidence. I have to my research to come up with a more concise answer.

The terminology does get a bit tricky, yes. I won't bore you with definitions because someone defined the terms fairly well a few posts above, but the comments in the initial post about creationists holding laws above theories struck my interest. First off, laws are not "above" theories; the scientific community prizes theories more than laws, but obviously both are important. The underlying implication here is that laws are always right and theories can be wrong, so we should always trust the whilom and hold off on the latter. Well, this is a completely ridiculous view because it's not true. Many of the "facts" that we call "laws" - like Newton's laws of motion, for example - are ontologically incorrect. In the Newtonian world, time and space are viewed as absolute and mass remains constant with acceleration, assertions that today we know are false yet assertions that are still presented as "laws." Why? Because even though they are not fully correct, they are still useful at a macroscopic level: we still employ classical mechanics to send space probes to the planets or to construct buildings and bridges. The classical mechanical picture of the world is wrong, but that doesn't mean we should expunge classical mechanics from our daily lives.

Theories have a larger scope than laws; they explain something fundamental about a wide range of phenomena and often introduce us to new areas of research, which means that scientific laws and principles are usually encompassed in some sort of theoretical framework. Theories can and have been wrong, but they also can be and (some) are right. There are theories out there that correspond so well to the particular materialistic portion of reality they aim to describe that they are essentially "true." The modern evolutionary synthesis, which unified Mendelian genetics and Darwinian natural selection, is one such theory. There are still tiny gaps here and there to complete, but the larger theoretical construct is dead on.

The goal of science is theory, NOT LAW!

What is the difference between a fact, a theory a hypothesis and a law?

A fact is something difficult to define completely, and is in many ways somewhat of an axiomatic concept. We presume that a fact is something discoverable by empirical observation, or logical inference - and that it corresponds to reality in that it is not contradicted by observation or logic.

In popular usage, a theory is something less than a fact. This is an ignorant view that confuses theorizing for hypothesing, or even merely guessing. A theory is actually a conceptual framework, designed to describe, explain predict and help control some phenomenon, based on a preponderance of facts. The theory supports itself with non-vague, operationizable predictions that are held to be accurate and in accordance with observed reality. Theories and facts are not antonyms - they are inter-related and interpedent. Facts are used to support theories, and theories explain existing facts and predict new ones. A great example would be Mendelev's theory of elements, better known as the "periodic table of elements." When Mendelev proposed his theory, it was considered ludicrous. However, without any knowledge of atomic structure, the theory predicted the existence of then undiscovered elements. When these predicted elements were discovered AFTER THE PREDICTION, AND NOT BEFORE, the truth of the theory was supported. In other words, the table predicted reality, and was then therefore supported by reality. Evolution is yet another theory that has overwhelming predictive power. That the term "theory", a concept which can only thrive in an ocean of facts, became seen as something less than a fact, is a testament to our society's scientific ignorance.

One of the most galling statements that can be made in reference to theories is the oft heard whine: "That's only a theory" as if to then claim that dogmatic "certainty" is superior theoretical tentativeness. The truth is that dogma often exists in stark contradiction to fact, while theory can only exist on the basis of facts. Another glaring difference between theory and dogma is that theory offers a coherent explanation of a phenomena. Dogma often offers nothing other than blanket authority statements concomitant with blatant threats of violence and harm to non believers.

A hypothesis is a tentative theory that has not yet been tested. It's an early stage in theory creation. Hypothesizing occurs early in theory formation, and is a bidirectional process. Typically, a scientist devises a hypothesis from his experience and his prior knowledge, and then tests this hypothesis experimentally. If the hypothesis is not refuted by experiement, the scientist declares it to be a theory.

An important characteristic of a scientific hypothesis is that it be stated in a "falsifiable" manner. This means that there must be some experiment or possible discovery that could prove the theory untrue. For this reason, a hypothesis should be stated in the form "If x, then y", meaning if we do or see X, then y must follow, otherwise, the hypothesis is false. An example of this is seen in Einstein's theory of Relativity. The theory made predictions about the results of experiments, such as "If a large mass moves near the path of a ray of light, the ray of light will bend. "If x, then y". We can watch large bodies in our solar system. The results of these observations could have produced results that contradicted Einstein, making the theory falsifiable.

We can see that even at the hypothesis stage, scientific thinking is superior to dogma, because religious dogma is not falsifiable. Everything religion says is held by its adherents to be true, no matter the outcome. In science, failed hypotheses are scrapped. In religion, "failed outcomes" are re-interpreted to fit the dogma. Therefore, it is of no use as a predictive tool, because it literally predicts anything and everything.

A law is an exact formulation of a principle (as in the law of the conservation of energy). Theories don't graduate into laws and laws are not former theories that are now somehow protected from disproof. This is another common misunderstanding. Both theories and laws add to our scientific understanding and one is not somehow superior to another. Laws, just like theories, can be refuted.

Basically, most people you meet won't have the slightest fucking clue as to what the terms: theory, hypothesis, fact and scientific law, really means, but they won't let ignorance get in the way of their acting like experts anyway. If you grasp the concepts, you already rate higher in scientific literacy than the majority of America.

 http://candleinthedark.com/scientific.html

Thanks. I might as well provide this whole list:

Commonly Held Myths about Science

Myth 1 - Science is a body of knowledge, a collection of facts

Anyone who has read this page knows that science is not merely a collection of facts, but a method of learning about the world, and error correcting what we already believe. This differs science from other authoritative bodies of collected "knowledge", such as dogma.

Myth 2 - Science claims to have "all the answers"

This is related to myth #1. While we learn about "science' in "science class" the scientific method itself is typically not taught explicitly in schools. For this reason, we come to see scientific facts devoid of the method of science, we come to see science as just "another subject" like English - a group of facts that we are to learn to the point of memorization, and never question. Science appears to us as a mystical and unknown authority, that claims to have answers to everything.

This is unfortunate, because science is all about questioning what we know. Science, by its real nature, is humble and tentative. It does not claim to have all the answers, in fact, what it claims to have is the best way to learn what the answers may be. Those who disagree are invited to offer their critiques of this falsfiable claim!

Myth 3 - Science is merely one more authority, like all other claims to knowledge.

Science not only asks us to question authority, it depends upon the questioning of authority! New learning often comes from refuting current claims about the world. While much of science does simply add to what we already know, the greatest scientific discoveries turned previous knowledge on its head (i.e. Einstein's relativity, quantum theory, chaos theory)

Myth #4 - Science changes what the 'answers" are all the time, making it unreliable

I first saw this claim on a creationist website. What this myth does is mistake the "error correcting" abilities of the scientific method for being "wishy washy" - it mistakes the tenatitve nature of scientific claims as "uncertain". At the same time, it mistakes the "certainty" of dogma for being "correct"

Being certain does not tell us that we are right, and in fact, being certain often keeps us from uncovering what the truth actually is. The scientific method recognizes that human dogma is merely a way to quell human anxiety, and not a means towards truth at all.

Myth #5 - "That's only a theory" i.e theories are just educated guesses.

This myth creates so many errors at once that it requires it's own section. In short, the idea that scientific theories are 'only a theory' mistakes a scientific theory for a hunch, or educated guess, rather than what it really is - a system of learned concepts that describe,explain, predict and/or guide us in how to control the nature or behavior of a specified set of phenomena, based on a preponderance quantifiable, observed data and supported by experiments that are capable of being replicated.

Myth #6 - Hypotheses Become Theories Which Become Laws

It is a generally held belief that there is a developmental sequence from hypothesis to theory to scientific law. This is actually backwards: theory is the goal of science! Laws are generalizations, principles or patterns in nature; theories are the explanations of those generalizations. A law allows us to make a prediction, but does not give us an explanation of the forces at work. A good historical example would be the fact that while the ancients could predict an eclipse, they had no idea what exactly an eclipse was. In fact, eclipse prediction was used in China to help avert dragons from eating the sun! Gravity is a modern example of a well-established law for which no really satisfying theory is available. We can make very accurate predictions using the Law of Gravity, but we don't have any consensus notion of how it functions!

Myth #7 - Experiments are the Principle Route to Scientific Knowledge While controlled, replicable experimentation is the best way to show causal relationships, controlled experimentation is not the sole means of creating scientific knowledge. Many fundamental discoveries in astronomy are based on extensive observations rather than experiments. 

An excellent post, todangst. I too am troubled by the lack of understanding of precisely what "science" is. Because of the accumulation of knowledge and increased specialization that has occured in the last 100 years, much of science has become extremely specialized, hence quite insular. Because it has a highly successfull track record, this creates the "myth of science" in the public eye that science constitutes a mystical authority. This is exploited by those who wish to propogate incorrect assertions, such as that "science is a religion". It is also a useful red herring for those who wish to attack "science" but are either unfamiliar with or cannot formulate an argument against the scientific methodology. This was a criticism I often levelled at Feyerabend.

For this reason, I often emphasize that knowing "scientific facts" no more constitutes "scientific literacy" per se than knowing the alphabet allows one to read a book. It is a necessary but not a sufficient condition.

If you do not mind, I wish to add a particular myth to dispel to your list. Like you, I found this on a creationist website.

The charge is: "Science cannot deal with anything outside our direct empiricism". Such claims are numerous. How can we know of atoms if they are too small to see? How can we know of evolution if we were not around to witness it? These claims are propogated by those who have a highly egregious understanding of the scientific method. The very purpose of science is by experimentation and observation to determine facts about the natural world that we could otherwise not gather! In this regard, especially in modern science, which deals mostly in things we cannot see, things we were not around to witness, things that are too far away to gain knowledge of otherwise etc. the very thing that methodologically constitutes "Science" involves designing a method that allows us to gain knowledge of a set of facts about the natural world which are then used to explain, predict and build upon other facts. Consider a very simple example. In Robert Boyle's experiment at Oxford, Boyle demonstrated the for an ideal gas of constant temperature, pressure and volume are inversely proportional. However, it is very difficult to do this directly. "Pressure" after all constitutes the amount of force being applied over a certain area. There is no device that one can insert into such an apparatus that would measure this directly. Instead, in the experiment indirectly measures pressure by attaching a gauge to an air pump that pushes oil into a sealed glass tube which compresses the gas inside at a fixed molarity. The gauge will measure the pressure applied by the pump, again, indirectly (the pump pushes a needle in the gauge which is driven by a mount that is fixed to the air tube).

Indeed, it is arguable that the whole of science constitutes indirect empiricism. There is no way to directly measure "temperature" of a macrosystem since that would literally entail counting all the particles in that system, recording their speeds at a certain instant, adding them up and dividing it by the number of particles. Rather, a device called a thermometer allows us to indirectly measure temperature by means of raising the level of an index of mercury in sealed glass vial against notches plotted on an arbitrary scale. The existence of neutrons can be demonstrated by applying an electric field to atoms of gold, which causes them to bend towards the Y-plate at a rate which is inconsistent with their atomic number. The number of neutrons a particle has can be derived this way (these results are in concordance with those of the periodic table). Electrons were not demonstrated to exist by scientists looking through femtoscopes to witness electrons. The charge effect created by firing particles at a phospholuminescent screen indicated that the particles had a negatively charged component. The fact that the particle would curve very sharply towards the positive plate indicated it had a very low relative mass. All this is an example of indirect empiricism, which is the foundation of scientific methodology. 

Because science constitutes to such a large degree of indirectly measuring and observing otherwise hitherto inaccessable variables and mechanisms, there is a confusing interlock of disciplines and theories. To that end, I argued that processes that rely on indirect empericism have an effect of confirming hypotheses in a bidirectional manner. For example, the experiment in which one demonstrates the existence of neutrons relies a priori on knowledge about electricity which was gained in previous experiments by virtue of similar methods of indirect empiricism. If any piece of scientific knowledge A is the necessary precondition for B , then the conformation of B independantly will act as a fortiori for A (not conformation, that would be circular reasoning). The existence of, say, proteins, unthinkingly relies on knowledge that atoms exist and constitute matter. WIthout this, there would not be proteomics. An experiment in proteomics that does not reference atomic theory, but relies on it that confirms a proposition about proteins that obviously requires atomic theory to be true solidifies it as a foundational theory.  Broadly:

Iff A is true then B could be true

B has been proven true

A is true

Obviously, we already knew A was true to begin with, but the point here is that where A is confirmed as true by an experiment independant of theories B, C and D which require A to be true, then any experiment confirming B, C or D independant of A will act as a fortiori for A. This is a fundamental principle of the accumulation of knowledge in science. These experiments which do not test a certain claim but test claims that could only work because of the claim in question therefore act as a fortiori for these claims. Note that these claims A which the proven hypothesis B relies on must have been proven independantly of and a priori to B otherwise the reasoning would be circular. 

Think of it as analogous to building a wall where more bricks on top solidifies those lower down. This has important applications in such things like applied science, where the construction of practical devices put to use acts as an affirmation of principles drawn up in the laboratory or on the blackboard.  This reminds me, another, unrelated but worse claim, is drawing a seperation between applied and pure science.