Prior to the 18th century, scientists depended on the Bible to inform their presuppositions. In the 18th century, James Hutton, known as the father of geology, suggested that the time line of the Bible wasn't long enough to account for all the earth's features to be formed. He observed processes such as erosion, runoff, flooding and deposition, that could account for the earth's features, given enough time.
Hutton speculated ". . . that processes occurring in the present were the same processes that had operated in the past, and would be the processes that operate in the future."* These thoughts were formalized as the Theory of Uniformitarianism. In the 19th century, Sir Charles Lyell popularized Hutton's ideas in his book, Principles of Geology (1830)*.
Let us use these two different Theories as major premises and see how they are used to interpret the same data.
First, let us limit ourselves to the class of rocks called sedimentary, those which appear to be formed from the deposition and hardening of rocks, sand, silt, and clay and those formed from prior plant and animal life, primarily oil, coals and carbonates. The other kinds of rocks, igneous and metamorphic, are not generally categorized in the same way as the sedimentary rocks, because of the absence of fossils in them.
Sedimentary rocks are found worldwide in layers. Each layer is identified because it contains the same materials and the same kind of fossils. Assuming that layers are formed as a process, the layers can be numbered or named in regard to where the layer fits in relation to the other layers. Assuming they have not been inverted, the ones on the bottom are considered to have been deposited prior to the ones above them, and the ones on the top are considered to have been deposited most recently.
A laboratory experiment can easily verify that these assumptions have merit. If I take a glass jar and pour black sand in it, then yellow sand, then red sand, followed by white sand, the layering of the colors corresponds to the order in which the layers were poured.
Geologists call the bottom layers the oldest ones and the higher layers the newer ones, thereby assigning a time dimension corresponding to the differing layers.
If you assume Uniforitarianism, all these statements are logically consistent, and indeed, this is the view of most modern geologists.
What if, on the other hand, you assumed Catastrophism? What if all the layers were deposited in the same period of time? What if a tremendous event eroded the land surface and mixed the sand in the sea bottom, all at the same time? In that case, the layering would not represent time, but it would represent something else.
A laboratory experiment can also be suggestive as to how layers could be formed in this scenario. Suppose I take a large bucket and pour in many different kinds of rock-making particles, from silts and clays to sand to pebbles to rocks. No matter what order I put these things into the bucket, when I add water and shake the bucket violently, the particles group themselves into layers, based upon particle size and density. The smallest particles group themselves at the bottom, and the largest ones are grouped at the top.
The rock layers exist, but what do they tell us? The meaning we give to them depends upon which major premise we use in our syllogism. The minor premises are the observations. There are layers. There is no argument about that. But there is room to argue on the meaning of the layers.
One geologists begins with Uniformitarianism and concludes the layers correspond to time. Another geologist begins with Catastrophism and concludes the layers do not correspond to time. Both geologists might have the same degrees and be equally competent scientists, but they have different starting points, different presuppositions, different faith-principles, different faiths.
Please note, the argument is faith vs. faith, not faith vs. science. Also note that these faiths used entirely secular terminology. One's faith doesn't have to be a religious faith associated with a particular religion or sacred text. Faith is what one accepts because he or she thinks it is true, not because it can be demonstrated to be true.
Notice that I have neither said that Uniformitarianism is true nor that Catastrophism is true. I have only demonstrated that choosing a theory or major premise to accept in an argument will determine your interpretation of the reality you are investigating. Obviously, we choose to believe things that do not conflict with what we believe based on our life experience. In this case, the theories are both bigger than anyone could experience in a lifetime, so neither theory conflicts with what we accept as true.
This still leaves the question, Are all theories equal? Does it matter what I presuppose? Is one theory better than another? I will try to address these issues in later essays.