The Use of Observation in Science.
We’ve all heard it, the claim that evolution isn’t science because it isn’t observable. Of course this is just an extremely narrow and convenient definition of science used by members of the creationist community to assure them their belief system isn’t threatened. It’s pretty obvious from the context that this claim is saying that if the evolution of one kind (not species) into another isn’t directly observable it isn’t a scientific theory. The idea that phenomena have to be directly observable to be a part of science seems to be limited to only those sciences that are a threat to theistic worldviews.
Contrary to what creationists want us to believe, there are several different forms of observation available to us. I like to break scientific observation into three categories. Sensory observation where an event, state or object is directly observable by human senses. Measurable observation where the phenomenon is indirectly observable through the use of tools. Trace observation is the observation of changes in an distinct and separate event, state or object caused by the phenomenon we are investigating.
Creationists will frequently mention gravity as an event that is directly observable so it fits into their narrow definition of science. To them the observation proves the science of gravity. However what they are doing is conflating the observable event and the explanation for the event we get from science.
In science an observation is made first. When we hold an object above the ground and then release it, it moves toward the ground below our feet. What we are really seeing are three different observations: the direction of movement, the consistency of that direction and the acceleration. Sensory observation tells us the direction doesn’t change with a change in release height. Measurable observation tells us the direction does change in a consistent manner – it curves. Sensory observation tells us the object accelerates as it moves toward the Earth. Measurable observation tells us the acceleration changes depending on the material below where the drop happens and where the Sun and Moon are in relation to that drop. Obviously, the sensory observation touted by creationists tells us less than measurable observation can.
Interestingly, trace observation can tell us more than either sensory or measurable observation can by themselves when we use scientific methods to utilize sensory observation and measurable observation to analyze trace observation. For example, noting an indentation in the ground and a number of objects surrounding the indentation we can not only determine which object fell, but the height it was dropped from, the direction it came and its condition after the impact. All without observing the object as it fell.
Science doesn’t prove things. That may be hard to get your head around, given the way science has been advertised for decades, but it’s a general truth. Science isn’t about proving, it’s about observing, making a guess about why that observation was made, testing that guess and guessing something different if the first guess was wrong. Science is also not a single method applied blindly, as we are led to believe by ‘the scientific method’ taught in school but a set of functional strategies for testing hypotheses specific to a problem or field of study.
Granted, sometimes the observation is made in areas where the average person has no knowledge, nor desire to know, but the guess is more than an educated guess and is based on the scientist’s unique and intense knowledge base, like physics, or mathematics. What is important is that the guesses, called hypotheses, can be tested in a real sense, as long as the observation is repeatable, or can be broken down into unique testable mini-observations. There are always two hypotheses being compared, even if one is just saying ‘you’re wrong’ so that the tests can be formed in a way where the answer is exclusive to both. Forming a test that answers positively for more than one hypothesis says very little, unless it can be further defined by different tests, or from an entirely different line of investigation.
It’s all about forming a hypothesis based on an observation(s), designing a test that will allow a prediction to be made, running the test and then comparing the prediction to the outcome of the test. The test has to limit the number of outcomes and the prediction has to be test specific: If the test produces outcome ‘a’ then hypothesis ‘A’ becomes more likely. If the test produces outcome ‘b’ then hypothesis ‘B’ is more likely and hypothesis ‘A’ becomes less likely. If the test produces outcome ‘c’ then we learn nothing about ‘A’ or ‘B’. Hypothesis ‘B’ may just be ‘Not A’.
If a single prediction/test pair cannot reduce the number of possible hypotheses down to one, a series or group of tests from different perspectives can. For example: If test 1 leaves five possible hypotheses out of ten with equal probability we learn something but not enough to be conclusive. If seperate test 2 leaves seven possible probabilities out of ten, but only three when used with the five left by test 1, then we’ve learned much more.
Let’s go back to the idea that the observability of gravity is what makes it provable science. The problem creationists have is gravity as a name we give to the consistent direction of movement of a dropped object isn’t a scientific explanation. It is a single point of data that needs explaning. Gravity could just as easily be angels pushing the object the direction God ordered them to, magic magnetism pulling all objects to itself, static electricity attracting the object, space-time pushing objects away from its expansion or a fundamental force where mass warps space-time. The simple observation tells us nothing about why or how gravity causes objects to move toward the Earth. Gravity is not its own explanation.
Gravity is an observation that elicits questions but explains nothing. The Theory of Gravitation however, not only explains the whys and hows of gravity, it presents science with further questions such as: is there a graviton particle, how does it relate to the quantum world, and will we ever have a theory of quantum gravity.
At this point you’re probably asking yourself what the heck this has to do with evolution as a science.
I’ve just shown that science is not limited to sensory observation and in fact trace observation when utilizing both sensory observation and measurable observation gives us a better explanation, which is the purpose of science, than sensory observation by itself.
As the creationists point out, we have never sensibly observed a chimp give birth to a human, nor have we found fossils of a crocoduck. What we have observed are the traces of the evolution from a chimplike mammal to modern humans from several different sources. Those traces come in the form of fossils, the order of stratification those fossils are found, the incremental change in shared traits and shared behaviour, and several different aspects of shared DNA including the one I find most interesting, the fused chromosome #2.
Taken one at a time, and without historical context, the evidence looks intriguing, but not convincing. However, looking at each source of evidence, every tested hypothesis, in the context of each other only one conclusion can be made. Homo not only is related to Pan, but they share a common ancestor.