Understanding Abductive Reasoning and the Historical Sciences:
It appears to me that many do not have a great deal of scientific and logic training. Sadly most schools do a fairly poor job in these areas and very few even teach logic at all. Even at University you generally need to do a course in Philosophy to get to do a unit in logic!
While I did 2 degrees in Physics, I only had real teaching/training in Logic when I did a course in Philosophy.
Understanding and observing the use of logical fallacies when reading argumentative essays and opinion pieces is really vital in this day of mass mis-information and mass formation psychosis. Being able to perceive the use of the straw-man fallacy or the genetic fallacy for example, are crucial to effective ‘critical thinking’ and improved comprehension.
When we are investigating past events from a scientific perspective whether the latest Big Bang Model for the origin or the Universe, or ‘Origin of Life’ hypotheses, we need to mainly use abductive reasoning as opposed to deductive and inductive reasoning.
So here’s a very basic primer. An Abductive argument has the following form:
- Major Premise: If A occurs, then B would be expected as a matter of course
- Minor Premise: The surprising fact B is observed
- Conclusion: Hence, there is reason to suspect that A has occurred.
Abductive reasoning, thus often affirms an historical occurrence and so is used by geologists, palaeontologists, archaeologists and evolutionary biologists, etc., to infer past conditions or causes from present causes/events.
Further than this, historical sciences investigate various hypotheses to see which hypothesis, if true, would best explain the known data.
This may sound simple but where there are a number of possibly adequate competing hypotheses, this can prove very difficult. Also to establish a casual claim, that is a valid and logically consistent link between the ‘probable’ events of the past and our current understanding or interpretation, this scientific approach requires the identification of three things:
1) Evidence that the cause proposed was present;
2) Evidence that on other occasions it has demonstrated the capacity to produce the effect under study, and
3) That there is an absence of evidence, despite a thorough search, of any other possible causes.
So, it is by using this approach we can look effectively at the various hypotheses for the ‘origin of life’ and make a reasonable evaluation of which hypothesis offers the best explanation. Unlike Physics where we can normally test our hypothesis for repeatability, etc. and therefore come to more firm conclusions, any conclusions in the historical sciences including evolutionary biology will normally have a degree of tentativeness to them.
For more on how this approach can help us actually establish a strong case for the very existence of the Almighty please see my article I wrote for some high school students, ‘Does God Exist’ – https://goo.gl/eWGEKH
The Cambrian Explosion:
An example of where abductive reasoning is used is with the Cambrian Explosion. Two expert palaeontologists Douglas Erwin and Eric Davidson have used this approach to rule out all known micro-evolution and macro-evolutionary processes. For example they state that the requirements for constructing animal body plans ‘de novo’ “cannot be accommodated by microevolutionary [or] macroevolutionary theory”.
Further they conclude that the cause of the origin of new animal forms on the Cambrian explosion must be capable of:
1) generating new form rapidly,
2) generating a top-down pattern of appearance and
3) constructing, not merely modifying, complex integrated circuits, but also that this cause is unlike any observed biological process operating in actual living population today.
Stephen Meyer (see Darwin’s Doubt) further illustrates that this cause must be capable of generating
1) digital information,
2) structural (epigenetic) information, and
3) functional integrated hierarchically organised layers of information.
So now considering the second option I listed in the abductive reasoning steps above, namely “Evidence that on other occasions it has demonstrated the capacity to produce the effect under study”, what conclusion might you come to?
What cause may account for this?
Firstly, it is also important to appreciate that the Cambrian Explosion poses a great (and in fact insurmountable) difficulty to both micro and macro evolutionary theories because of the ‘inverted cone’ of disparity preceding diversity.
That is the appearance of new animal forms in the Cambrian Explosion shows a ‘top-down’ pattern of phyla-level morphological disparity (i.e. a lot of new animals and species), followed by species level diversity.
As an analogy to help explain it, it’s like creating different modes of transport like trains and automobiles, then and only then creating the different automobile types of family car, truck, van, ute, etc.
The only known ‘cause now in operation’ (see original 3 point abductive reasoning structure) is the theory of Intelligent Design (ID). It is intelligent agents that have the capacity to introduce complex technological systems into the world fully formed often with very little resemblance to earlier systems. For example, when first invented and created the radio was unlike anything that had come before.
For an introduction to ID please see my 4 sessions that I presented to Senior High School students – available on the ID tab at www.circumcisedheart.info
If interested in much greater depth I can recommend a few books by leading ID proponents such as:
- Will Dembski: see for example The Design Revolution and The Design of Life (co-author Jonathan Wells)
- Stephen Meyer: Darwin’s Doubt, Signature in the Cell, & The Return of the God Hypothesis
- Philip Johnson: Darwin on Trial
I can recommend many others as well if desired.