Science, Observation, and Reason Scientific Method is used to construct scientific knowledge about nature. Knowledge is increased through careful observation and logical inference. Observation, inference, and knowledge are almost always fused together to some degree. For example, much of our observation of the world is recognition of the familiar, which is observation informed by knowledge. Also, most of our observations of objects in the world are informed by inference, because the information from our senses in quite superficial by itself. Using vision, we only really see surfaces, shadows, colors, patterns: but we observe objects having depth and volume and texture. Using hearing, the various noise we hear become the sounds of things near and far, like approaching cars or hidden animals. Our ordinary everyday experience of the world is a type of knowledge, which we can characterize as practical reliable knowledge. Although this knowledge of ordinary experience is often mistaken, it works well enough for our daily activities. Examples are gathering vegetables and cooking them for a nutritious meal, or weaving cloth and sewing it to make clothing. Empiricism and Rationalism Philosophers who believe that experience is the source and ultimate justification for all knowledge are called empiricists. Some empiricists have looked to experience to provide a higher type of knowledge than practical reliable knowledge, a type of knowledge that is infallible and certain, which will never turn out to be false. But not all empiricists search for certain, perfect knowledge -- we might call those who do undertake this search "extreme empiricists". There have been few extreme empiricists, since there are serious problems with trying to find reasonable cases of experiences that give perfect knowledge about the world. These problems are so severe that other rival philosophers have concluded that experience by itself cannot be a source of perfect knowledge at all. Indeed, most empiricists do accept that experience needs help from reason to establish knowledge about the world. However, experience (even with help from reason), can never establish perfect knowledge about the world (as will be explained below). A philosopher searching for perfect knowledge will conclude that experience cannot play any role in perfect knowledge. What other source of perfect knowledge is possible? The alternative to experience is reason, and philosophers who emphasize the large role that reason must have for knowledge are called rationalists. Some rationalists, searching for perfect knowledge, will use only reason to find knowledge, and we might call them "extreme rationalists". As it turns out (also to be explained below), reason by itself cannot establish any perfect knowledge about the world. That is why there have been few extreme rationalists in the history of philosophy. Most empiricists have decided that experience needs a little help from reason to establish knowledge, and most rationalists have concluded that reason needs a little help from experience to establish knowledge about the world. Debates between these empiricists and rationalists are surveyed by this article about "Rationalism vs. Empiricism". If both sides assume that perfect knowledge must be the quest, then both sides must fail. Experience and reason can indeed be artificially separated from each other, in the philosophical imagination (again, far from our ordinary experience in which observation, inference, and knowledge are partially fused together). By artificially separating experience from reason, extreme empiricists and extreme rationalists actually destroy the possibility of knowledge about the world. That is why most philosophers conclude that both experience and reason are needed for knowledge about the world, and the difference between empiricists and rationalists comes down to different estimates about how much experience and reason contributes to knowledge. In the extreme empiricists' philosophical imagination, experience is "purified" of anything that might admit the possibility of error and illusion, and the empiricists announce the discovery of a realm of "sensations" or "sense data" that can never prove false. Example: "There is a bright point of light." In this example, a person making this judgment is claiming to observe something and describe it so narrowly that she can never be shown to be wrong. If instead she claimed, "There is a star in the sky", this judgment could conceivably turn out to be wrong, because we can imagine how further investigation could show that what this person really experienced was not a star (but instead a planet, or an airplane, etc.). The problem with pure sensations, even when described in infallible ways, is that they cannot help establish knowledge about the world. Knowledge consists at least of judgments about the world expressed in propositions of some public language. If pure sensations are expressed in judgments, they either (1) fail to be about the world, and instead are about some realm of pure experience (just lights and colors and noises and tastes, etc.); or (2) they try to be about the world but begin to suffer from the possibility of error and illusion (e.g. is that really a circle of light, or maybe an ellipse -- and is it red, or reddish-orange? etc.). Furthermore, anything like scientific knowledge about the world would at minimum consist of judgments about the regular behavior of objects and events in the world. Yet pure experience cannot establish these sorts of judgments because of the "Problem of Induction": even though a series of experiences may have common features, and appear to present a pattern, it is impossible to have perfect knowledge that this pattern would continue into the future. Empiricism's quest for perfect knowledge through experience alone can therefore only lead away from knowledge about the world and can never produce anything like scientific knowledge. In the 20th century, scientific anti-realists have generally preferred types of Empiricism (like positivism's view that science can only describe patterns of phenomena). On the other side, in the extreme rationalists' philosophical imagination, reason must have a method of inference for establishing perfect knowledge. The only method of inference that promises to prevent all possibility of error is deduction. Deduction is a careful relation between premises and a conclusion, designed so that if you know that the premises are all true, you can also know that the conclusion is true. So long as the premises remain true, the conclusion can never turn out to be false, and your knowledge of the conclusion is perfect knowledge. You can read an advanced article about "Classical Logic" here. The difficulty with deduction is that a person's perfect knowledge of conclusions depends on perfect knowledge of the premises. How can a person perfectly know the premises? Well, perhaps other deductive arguments show that each of the premises are knowably true. Ok, but those additional arguments must have their own additional premises, which all need their own deductive arguments to justify why they can be known to be true, and so forth, and so on -- are an infinite number of arguments needed for any knowledge? That seems strange, since no person could hold an infinite number of arguments in their mind, and thus can never be assured that perfect knowledge is achieved. There are two other alternatives: (1) perhaps some premises can be known to be true without any argument (see "Foundationalist Theories of Epistemic Justification"), or (2) perhaps some special conclusions can serve as premises for other arguments, which in turn prove conclusions that serve as premises justifying those special conclusions, so that only a finite number of arguments are actually needed (see "Coherentist Theories of Epistemic Justification"). Rationalists have usefully developed the foundationalist or coherentist alternatives, and these developments are very important for scientific method and realism, so they will be discussed further in sections below. However, extreme rationalism is a dead-end because pure deductive inference (nor inductive or abductive inference either -- more about these below) cannot establish any perfect knowledge about the world. Reason by itself can form perfectly coherent systems of thought, but there is no way to determine which system must be true, and most are quite compatible with the natural world. In other words, pure reason's truths are either (1) not about the natural world at all, or (2) somehow they are true about all possible worlds. Most rationalists therefore admit that reason needs some information from experience in order to produce knowledge about the actual natural world (thus agreeing with most empiricists that experience needs some assistance from reason). The endless debates between extreme empiricism and extreme rationalism are inconclusive, because each side can show why the other side must be inadequate. Experience by itself cannot be a path to perfect knowledge about the world, but reason alone cannot establish any knowledge about the world either. Most philosophers turn away from this fruitless debate and take a compromise position that could be called "Rational Empiricism": knowledge about the world is created by experience and reason working closely together. However, rational empiricism is a philosophical position that admits that perfect knowledge about the world is never possible. There may be types of perfect knowledge, but none of them can be about the actual natural world. Since scientific knowledge is about the natural world, then scientific knowledge cannot ever reach perfect knowledge, and therefore any scientific knowledge is less than certain -- instead, scientific knowledge, even at its best, is always fallible (could be exposed as false in the future) and revisable (could be improved or entirely replaced with better scientific knowledge). The scientific method itself is not a case of perfect knowledge either -- rather, scientific method is a tool that can be (and has been) modified and improved through regular use and testing. Furthermore, although there is general scientific method that is explained here, each of the sciences uses its own specific version of the scientific method that works best for that science. Scientific Observation We can now ask this question: what is the relationship between the knowledge of ordinary everyday experience and scientific knowledge? Is scientific knowledge a quite different sort of knowledge from ordinary reliable knowledge? This introduction to scientific method takes the position that scientific knowledge is also a kind of reliable practical knowledge, but vastly improved: the reliability and practicality of scientific knowledge is far greater than that of ordinary everyday knowledge. Also, the scientific method depends on ordinary experience, but often must improve that experience for its own purposes to become scientific observation. A person makes a scientific observation by properly using an approved instrument (one that has the confidence of the scientific community) for focus and/or measurement to carefully experience a thing or event that is public (could be observed by others too), and the person makes a record of the observation using a description that is precise (the thing or event is described in a more formal way than ordinary language, using special concepts and categories to increase discrimination and accuracy). The best kinds of scientific observations are designed to be both precise and public: these observations are described using concepts and categories specially designed and used by a scientific community of people, all trained for making good observations. Example: Measuring the movement of a planet across the sky from night to night across two years' time. The astronomy community designed a system of concepts and categories (right ascension and declination) for describing the exact position of any object in the sky. Using this system, any trained and careful observer will be able to accurately record the position of a sky object. When a community of scientists all use the same system for observation, and are well-trained to perform observations using this system, the community has established the possibility of scientific objectivity: scientific knowledge about natural objects and events within experience. This scientific objectivity, which provides reliable and practical information about objects and events, is the starting-point of scientific method and makes science possible. The scientific method uses experience to produce knowledge, but not just any sort of experience: only scientific observation counts. Of course, scientific observation is still fallible and revisable, since scientists make errors and misjudgments even when sincerely trying to do their best. The best kind of scientific observation is highly objective by being repeatable and durable: lots of scientists have been able to make the same observation (or almost the same, within a reasonable amount of error) over long periods of time. Observation, inference, and knowledge are always fused together to some degree. This is true for ordinary experience, and it is true for scientific observation. For example, when astronomer Tycho Brahe observed and recorded the positions of the planet Mars during the late 1500s, he used a telescope. Brahe's observations enjoyed a high level of scientific objectivity because of their precision and replicability, which was only possible by using his excellent telescope. Only an instrument already approved by a scientific community, which agrees on how that instrument is correctly used, can be used to make scientific observations. The scientific community endorsed the use of the telescope because by that time, scientists understood how telescopes work and they trusted well-made telescopes to accurately magnify the visual image of the object viewed. Scientists had reliable and practical knowledge about telescopes, and they also had by that time a well-established theory about how a telescope worked, from the science of light and optics. In summary, Brahe was able to make scientific observations of Mars because his experience was enhanced by inferences from what he saw through the telescope to make conclusions about the position of Mars in the sky, and these inferences depended on his knowledge about the telescope. A scientist's own senses can qualify as scientific instruments. For example, a scientist's own eyes can be adequate instruments for making scientific observations. Unless Brahe's eyes were adequate instruments for looking through the telescope properly, his observations would not have been accepted as scientific by the community of scientists. The trained eyes of a botanist are used to make scientific observations about the structures of flowers. The trained ears of a ornithologist are used to make scientific observations of bird calls, as another example. Scientific observations are observations about natural objects that really exist. How do scientists know that their observations are truly of things that really exist? Rational Empiricism would say that a valid observation is an experience aided by inference and knowledge. A scientist must have an experience of an object that includes its "identifying qualities". The scientist already knows what qualities a certain thing must have, which identify it. In the observation of a thing, the scientist looks for its identifying qualities, and when those identifying qualities are observed, the scientist infers that it is indeed that particular thing which is observed. This inference could be mistaken (maybe other things also have that quality), so a scientific observation remains fallible, like any knowledge. Scientists reduce the possibility of mistaken identifications by having rigorous tests for several qualities that uniquely identify particular things. Science makes a useful distinction between a thing's qualities that depend on their being observed ("perspectival" qualities), and a thing's properties that exist regardless of whether they are being observed ("independent" qualities). Perspectival qualities only exist when organisms are perceiving them: colors, sounds, tastes, textures, etc. Independent qualities exist even when they are not being perceived, although we naturally detect them using perception: shapes, mass, size, etc. Also, science makes a useful distinction between those perspectival qualities which can be observed by the unaided senses ("directly observed" qualities), and those which can only be observed through mechanical instruments ("instrumentally observed" qualities). Finally, some independent qualities are detected only by inference from other instrumentally observed qualities. Five kinds of qualities are therefore discriminated by science, according to the method of their identification: (1) the directly observed perspectival quality (DOPQ). Examples of using a DOPQ: a chemist identifying a mineral by its color, a ornithologist identifying a bird by its song, and a geologist identifying a rock by its texture. (2) the instrumentally observed perspectival quality (IOPQ). Examples of using a IOPQ: an astronomer identifying a red giant star by its flickering color through a telescope, and submarine sonar operator identifying a surface vessel by its amplified propeller noise. (3) the directly observed independent quality (DOIQ). Examples of using a DOIQ: a paleontologist identifying a fossil bone by its shape, and an oceanographer identifying a tide by the water height. (4) the instrumentally observed independent quality (IOIQ). Examples of using a IOIQ: an official of the bureau of weights and measures using a standard gallon container to identify a full gallon of gasoline from a station pump, and an engineer using calipers to measure the size of a machine part. (5) the instrumentally detected independent quality (IDIQ). Examples of using a IDIQ: a physicist identifying a metal by calculating its density from its measured volume and weight, and a geologist identifying an iron ore by measuring its magnetic attraction. In actual scientific practice, identifications often use a combination of two or more of these means. There is one kind of natural entity which must receive additional scrutiny: that entity which, due to the scientific conception of that entity, can only be identified by one or more IDIQs, and thus cannot be identified by any direct or instrumental observation. Examples of such non-observable entities are black holes, the force of gravity, and the curvature of space-time. Evidence for such entities will only consist of the detection of their effects on scientific instruments. Summary 1. Observation, inference, and knowledge are almost always fused together to some degree. 2. Scientific observation requires a combination of experience and inference, and a person can make a scientific observation only after training and approval by a scientific community. 3. There are five important kinds of qualities that can be scientifically observed. Copyright 2011 John R. Shook