In its simplest form, the Scientific Method is a method of drawing conclusions based on evidence. It sounds a bit silly to have a semi-glamorous name for such an obvious method, but you’d be surprised how often experts and non-experts alike draw conclusions without enough reason to do so. This is often a biased method that leads to a conclusion that suits the concluder. The Scientific Method is intended to strip away bias, conjecture, and belief, leaving the truth.
The necessary method of drawing scientific conclusions has been debated throughout history and early signs of it go as far back as Ancient Greece. However, the emergence of empirical scientific methods, that is, the collection of data through the use of observation and testing, largely emerged during the Scientific Revolution of the 16th and 17th centuries and culminated with Issac Newton’s conclusions about gravity and the laws of motion.
Prior to the Scientific Revolution, much of the world was explained by myths with the flat earth belief being a notable example. But as empirical methods of observing and testing the physical world emerged, Newton and others started to develop hypothesis about how the world worked and then used testing and observation to prove them. While the story of Newton’s hypothesis about gravity emerging from getting hit on the head by an apple falling from a tree is likely a myth (due to the absence of any evidential support), the principles of gravity that Newton developed are not a myth and are grounded in mathematics and science that have stood for hundreds of years.
You may think that by the time we’ve made it to 2024, people would have an understanding of the scientific method, but we are constantly battling the forces of unsubstantiated conclusion. The Scientific Method involves the development of a hypothesis prior to testing and the eventual formation of conclusions or a theory. It’s often easy and comfortable to skip the observation and testing part and go directly to the conclusion. I hear people say that they have a theory on various events that occur in the world, like why a mouse entered their house, why their tire went flat (example to come later), or why the trash collectors didn’t stop at their house. These often-well-meaning theorists are not developing a theory, but rather, a hypothesis. A hypothesis is an assumption made for the sake of argument or in many cases, for the sake of benefit to those in need of answers. Hypotheses and theories are often used interchangeably in non-scientific arenas, but they are certainly different. A hypothesis does not involve the analytic rigor required to make substantial and scientifically grounded conclusions.
The definition of scientific evidence and testimony has been debated in the court system as well. The current standard in Federal court and some states for the admission of expert testimony was developed starting with a 1993 case Daubert v. Merrell Dow Pharmaceuticals, Inc. When an expert’s testimony is questioned by an opposing expert, it is often referred to within the expert community as a Daubert challenge.
In Daubert, a claim was made that a drug produced by Merrell Dow Pharmaceuticals caused birth defects. The evidence to support this, along with the correlation between the birth defects and the use of the drug, was based on in vitro and in vivo non-human animal studies which were not generally accepted within the scientific community. The expert’s testimony was excluded because of the absence of accepted scientific methods. The judgement about the acceptability of this evidence, along with other cases involving scientific testimony led to the development of the standard for drawing scientific conclusions as an expert witness.
Other cases contributed to the development of the Daubert standard, including a good example of the difference between correlation and causation in Kumho Tire Co. v. Carmichael in 1999. This case involved the failure of a tire that caused injuries and one death. The expert witness said the cause of the failure was a defect in the tire itself effectively blaming the accident on the tire manufacturer. The reason for this conclusion was described by the expert as being the absence of any information to the contrary. In other words, the expert drew this conclusion through a process of elimination and not the review of evidence that supports the conclusion directly. This is a good example of a method of drawing a conclusion that is not consistent with the Scientific Method. This expert developed a hypothesis, but did not support or prove the hypothesis through observation or testing.
The use of correlation to support a conclusion is common and is often the reasoning used in construction-related cases where liability is in dispute. Just because the contractor installed the steel beam that failed, or the brick façade that fell off, doesn’t mean they are responsible. Just because your adjacent neighbor is renovating their house and making noise and vibration doesn’t mean your foundation cracks are caused by your neighbor.
Several parties are involved in the construction process and a scientific method of determining the causes of failures and losses is necessary. As forensic engineers, we must differentiate between hypothesis and theory. While a theory is not infallible, it is supported by data and evidence while a hypothesis is not. For us to confidently state, perhaps under oath, that we used the scientific method to draw conclusions, we must have the data, observations, and evidence necessary for support.
