# How/Why is the explanation/prediction of physical phenomena not deductive?

Why is the explanation of the triboelectric effect or the electrostatic effect(indicative examples) not deductive?

How so we have a set of premises and from them follows the conclusion which is what we are trying to explain and hopefully predict so as to reproduce if needed.

• Because we do not have any set of premises, we have a set of observations/measurements to be explained and/or predicted. The passage from that to the model ("explanation") has little to do with deduction, and is usually called abduction. And this is true even when the model is within a framework of some mathematized theory, like classical mechanics, which is not that common. Axioms of classical mechanics do not tell us what even a pendulum should be modeled as, let alone more complex phenomena. It is done based on heuristics, analogies, trial and error, plausible but informal reasoning, etc. Commented Mar 24, 2020 at 7:10
• @Conifold The question was inspired by philosophy.stackexchange.com/questions/70958/… why is the expanation of physical phenomena abductive as opposed to deductive. I think I am still not clear on the distinction of abduction and deduction which was why I added phillosophy of logic as a tag, It is a bit cyclical. You said we don't have an axiomatic system because the reasoning is not deductive and then you said the reasoning is not deductive because we lack an axiomatic system. Explain 1 of these two in other terms Commented Mar 28, 2020 at 1:46
• @Conifold Please clear me up on the distinction, first abstractly and then in concreto explain why Physics is abductive as opposed to deductive. Commented Mar 28, 2020 at 1:47
• SEP already did the job, Deduction, induction, abduction. Commented Mar 28, 2020 at 1:48
• @Conifold Could you please then explain in concreto why the reasoning in physics is abductive instead of deductive without any mention in any axiomatic system( lacking or not). Commented Mar 28, 2020 at 1:54

Kαλημέρα! What's left of the dwindling Greek community in Chicago sends its regards.

The nature of your question really generalizes to a good philosophical question. How is an empirical explanation like that of electrostatics not deductive?

The short answer is, it is to an extent. However, it is not primarily a deductive activity. There are many ways science is done ranging from the methods used by particle physicists to those of ecological biologists to those methods of social scientists like economists. Each has a related, but different philosophical method, different tools, literally and metaphorically, and different matters of study that lend themselves to discovery and explanation in different ways. While science may replace branches of philosophy, philosophy attacks problems in ways no science can.

Even among a hard science, like physics, there are differences such as those among particle physics, cosmology, and materials science. This range of scientific methods is infamous as the philosophical problem of the demarcation of science which I believe stems more from adhering to the notion that classical sets are better tools for classification than fuzzy sets. There are deep divides in philosophical positions based on metaphysical presumptions such as one's valuation of the value of keeping an eye on Wittgenstein's notion of family resemblance or adhering to the law of the excluded middle in one's logics. Tempted as I am to perch on my soapbox, let's move forward.

You probably know, it is likely the English word 'electron' has an etymology ultimately derived from the ancient Greek 'amber'. Did Thales of Miletus, Heraclitus of Ephesus, or Galen of Pergamum use deduction when exploring the natural world? Yes! How about Galileo Galilei, Rene Descartes, or James Clark Maxwell use deduction? Even more so with the mathematization of science, surely. But, explanations do not conform well to purely deductive models, most famously, the Hempelian deductive-nomological model. To clear up your misunderstanding, you need to get to the current understanding of explanation within the philosophy of science.

I recommend Blackwell's Companion to the Philosophy of Science. though I think Routledge may have one. There are others, but it's easier than working through SEP or the Encyclopedia of Philosophy. On page 127, W. H. Newton-Smith says:

Very few explanations actually encountered in everyday life or in science have [a deductively] precise form.... we sketch part of a story which we are betting could be elaborated so as to incorporate appropriate laws, given further empirical [emphasis mine] research.

Indeed, unlike mathematics which is primarily viewed as a deductive activity like as Euclid's geometry, science is much more in the spirit of trial and error, and has a strong component of engineering which proceeds from watching prototypes fail. Like logic, math is generally limited inadequately describing the world, and whole theories of math deal with uncertainty such as statistics, stochastics, and chaos theory. The very ontological nature of the electron itself is mathematically uncertain. Even Newton's vaunted laws of gravitation become almost useless when a third body is added to a dynamic situation.

Deductive logic and math play a role in electrostatics, certainly, but there are other forms of explanation. Another aspect of electrostatic explanation can be viewed in terms of causality, which is a philosophical problem in and of itself. Some scientists go so far as to reject it completely preferring to see all systems as possessing latent variables which undermine deterministic certainty. Math, after all, is a model of the universe, not the universe itself (despite the recent fad of considering the universe a simulation without empirical evidence).

So, in terms of causality, particles are unpredictable and not subject entirely to deductive logic. This is why the causal-relevance model of explanation offers a complementary tool for dealing with understanding electrostatics. In the C-R model of phenomena, they are understood in terms of causally relevant features which aren't arrived at through a priori reasoning but from a posteriori experience, which is the heart of the empirical tradition. Modern chemistry started off as two distinct types of alchemy, those of living substance and those of non-living substance. Through experiment, chemists eventually rebutted the logical conclusion that living substances were animated with an elan vital leading to the abandonment of vitalism. An understanding of electrons has always been facilitated by deductive reason, but far more inductive and empirical methods. This is why abductive logic is generally seen as the primary way we form explanations about phenomena. Human logic is largely defeasible. Intellectuals have tended towards certainty in methods, but the universe and the mind are largely non-deterministic.

In fact, other models besides the D-N and C-R models of scientific explanation abound. Again, according to Newton-Smith on page 130:

We have an embarrassment of riches. We have explanations by reference to causation, to identities, to analogies, to unification, and possibly other factors. Philosophically we would like to find some deeper theory that explained what it was about each of these... forms... that makes them explanatory.

So to conclude, electrostatics can be seen as partially deductive, but there are more important characteristics of the theory including abstracting causal models, inductive thinking, and defeasible reasoning based on experimentation. Science is not the axiomatic method of reasoning but requires experimental apparatuses and debates.

• Is a probabilistic prediction then not a prediction in the first place? Fuzzy sets are fine as long as the degree of belonging can be measured. It's not binary it's graded fine one only needs to be told how much does X belong in a set. Commented Mar 30, 2020 at 18:54
• @GeorgeNtoulos Probabilistic predictions are predictions, but if they are accurate, they are not deductive conclusions because by definition, a deductive conclusion must follow with certainty. Probabilistic conclusions are by their nature inductive conclusions, because to establish probability (to be fair, there are three notions of probability), events have to be repeated. So, the use of predictions and probability are inductively inferential acts pertaining to the conclusions themselves. This is what makes science borrow more heavilty from empiricism than rationalism.
– J D
Commented Mar 30, 2020 at 18:58
• Wouldn't kolmogorov's axioms of probability, Frequentist definition of probability, And the definition of fair die as a die that has equal probability in all faces along with the statement that the specific fair die has 6 faces lead to a deduction that Each face has 1 sixth of a probability of happening? Why does my probabilistic inference lack certainty? I did not say that something will happen I said that the chances of that something happening are X. Commented Mar 30, 2020 at 19:27
• @GeorgeNtoulos Excellent question. My immediate response would be that with a logical conception of probability, where probability is seen as representing sets of events or propositions, what matters is not whether or not the math is certain, because certainly any probability theory built from an axiomatic system would have theorems that are deductively certain, but whether the conclusions drawn from the theorem are certain. Science can build a statistical picture of weather, for instance, using probability models, but what weather actually does is uncertain...
– J D
Commented Mar 31, 2020 at 16:29
• Thus, it is the propositions about the weather that remain uncertain, not the propositions about the probability. From a computer science perspective, one can have an absolutely deterministic device such as the Turing machine produce non-deterministic data. That doesn't even begin to cover other theories of probability such that they are actually qualitiies of physical phenomena and thus only knowable by methods of observation and induction.
– J D
Commented Mar 31, 2020 at 16:38

Why is the explanation of the triboelectric effect or the electrostatic effect(indicative examples) not deductive?

This is because the world is given to us but we are not given an axiomatic system. By finding the appropriate questions to ask and then understanding the how and the why we construct a theory of the world and then we can attempt to put it in axiomatic terms and its within that system that we have formal deductions.

It's worth pointing out that even in a deductive system we can can have induction, that is understanding what are the useful questions to ask.