Tag Archives: Theories

Scientific Models

I recently attended a book club discussion on The Meme Machine by Susan Blackmore (see here).  In it, Blackmore puts forth a thesis of “memetic evolution” to describe how our minds work. In fact, her assertion is that our minds can only be understood in terms of memetic selection. Although that seems to be a wildly exaggerated claim, the scientific model she proposes is both stimulating and promising.

But memetic evolution is not the topic of this article. I only cite it as one example of the kind of topic that  many non-scientists and even some scientists have great difficulty discussing fairly. Often in discussing such topics, a great many unfounded criticisms are lodged, and these quite often flow from an inadequate understanding and appreciation of scientific models.

This is understandable. Unless you are a trained, experienced, and particularly thoughtful scientist, you probably have had inadequate background to fully appreciate the concept of a scientific model. In fact, if you look up the word model in most dictionaries, the scientific usage of the term is typically not even mentioned. No wonder many people have a very limited if not completely mistaken appreciation of what a scientific model is. A scientific model is not analogous to a plastic model kit that is intended to look just like the real race car in every detail. It is not at all like a fashion model, intended to present something in an attractive manner. Nor is it like an aspirational model to be put forth as a goal to emulate and strive toward.

No, a scientific model is a working system that does not need to actually “look like” the real system it describes in any conventional way. The important characteristic of a scientific model is that it behave like the real system it describes. How accurately a scientific model reflects the real system it models is measured by how well it explains observed behaviors of the real system and is able to predict future behaviors of the real system.

For example, in 1913 Ernest Rutherford and Niels Bohr put forth the atomic model of matter that we are all familiar with – a nucleus of protons and neutrons orbited by electrons. This was a highly successful model because it described a huge number of observed characteristics and behaviors of matter, allowed us to gain great understanding of matter, and most importantly allowed us to predict as yet unobserved traits of matter.

But in truth the Bohr model is a laughably simplistic stick-figure representation of matter. It describes certain behaviors adequately but completely fails to describe others. It was quickly extended by De Broglie, by Schrödinger, and innumerable others to include wave and then quantum characteristics.

Despite its almost laughable simplicity and innumerable refinements and extensions made over the last century, the Bohr model remains one of the most important and consequential scientific models of all time. If the Bohr model was presented in many book discussion groups today, it would be criticized, dismissed, and even mocked as having no value.

Certainly we can and should recognize and discuss the limitations of models. But we must not dismiss them out of a mistaken lack of appreciation of the limitations of scientific models. Often these misguided criticisms have the more widespread effect of unfairly discrediting all science. Following are some examples of the kinds of criticisms that are valid and some that are invalid.

  1. We must first recognize when we are talking about a new idea like memetic evolution, that we are talking about a scientific model.
  2. A scientific model does not need to answer everything. We must recognize the limitations of every model, but the more important focus is on how useful it is within its applicable limits. Newton’s Laws do not describe relativistic motion, but in our everyday world Newtonian physics is still fantastically useful. Critics of science should not claim that a model – or science in general – is fundamentally flawed or unreliable because a particular model is not universal.
  3. Many critics of science think they have scored points by pointing out that “you can’t trust science because their models are always being replaced!” But models are hardly ever replaced, rather they are extended. The Bohr model was greatly extended, but the basic model is still perfectly valid within its range of applicability.
  4. The fact that there are many different models of the same thing is not proof that “science contradicts itself and cannot make up its mind.” We famously have the two major models of light- the wave model and particle model. The wave model correctly predicts some behaviors and the particle model correctly predicts others. Though they appear irreconcilably different, both are absolutely valid. Real light is not exactly like either model but is exactly like both models. Think of your mother. She has a mother-model that describes her behavior as a mother. But she also has a wife-model, a career-model, a daughter-model, a skeletal-model, and many others. None of these in themselves completely describes your mother, and many may seem irreconcilably different, but all of them correctly model a different set of behaviors in different situations and only collectively do they all communicate a more complete picture of your mother.

So, when discussing something like memetic evolution, it is proper and correct to ascertain its boundaries and to critique how well it describes and predicts observed behaviors within those boundaries. But it is wrong and counter-productive to dismiss it either because there exist other models or because it does not – yet – describe everything. And worst is to dismiss all of science as flawed because it puts forth multiple models of reality and extends them over time.

To describe and predict human thinking, Skinner put forth a stimulus-response model, Blackmore puts for forth a meme-model, and I often focus on a pattern-recognition model. These are not in competition. One is not right and the others all necessarily wrong. The fact that there are these three and many other models of human thinking does not reflect any fundamental weakness of science, but rather its strength.

It us unfortunate that far too few people have a sufficiently deep appreciation and level of comfort with scientific models. We must do much better to understand and communicate these subtleties that are so fundamental and critical to science.