Deductive & Inductive Reasoning

[MHLee2017]

Hi who may concern,

 

We know that there are mainly two way inductive and deductive reasoning to prove a scientific theory. Inductive reasoning is proving something from observation and generalise it whereas deductive reasoning is another way round. Most of the law and theory are proved by using inductive reasoning. My question is that "is there any scientific theory proved by deductive reasoning?" Thank you.

[Strange]

I guess it could be argued that theoretical physics works deductively while discoveries made through experimental physics are more inductive.

 

So, I would say that Relativity, for example, was developed deductively from a few simple premises. However, that doesn't "prove" the theory. It still needs to be tested against observation. But that is true of a theory developed inductively, as well. (No theory is ever "proved" anyway.)

[Raider5678]

No theory is ever "proved" anyway.

I have a theory that If I let go of this apple while standing on earths surface, if will fall towards the center of gravity.

[Strange]

I have a theory that If I let go of this apple while standing on earths surface, if will fall towards the center of gravity.

 

 

Yes, you can find evidence that is consistent with the theory. But that doesn't "prove" it because one day you may find some other evidence that shows it to be wrong in some way.

[Raider5678]

 

 

Yes, you can find evidence that is consistent with the theory. But that doesn't "prove" it because one day you may find some other evidence that shows it to be wrong in some way.

Yes, that aliens exist and that they created an artificial organic matter magnet to attract apples to the center of the earth, even though that's not actually the center of gravity. Bingo.

[MHLee2017]

 

 

But that doesn't "prove" it because one day you may find some other evidence that shows it to be wrong in some way.

I get what you mean here. But then will you argue that if a theory is not falsifiable, meaning it can't be proved wrong, is not true?

[Sriman Dutta]

I get what you mean here. But then will you argue that if a theory is not falsifiable, meaning it can't be proved wrong, is not true?

 

A theory may be true to some but not true for all. I cite here two examples.

 

Classical electrodynamics work excellent when dealing with real-life practical cases. The Larmor's formula states that any electrically-charged body radiates out power when moving in a circular path. That's perfect. So it is true. But this theory doesn't hold true for situations at the quantum scale. A moving electron, according to the Larmor's formula, should radiate out power and should eventually go spiral round the nucleus and finally collapse with the atomic nucleus. But this never happens. The electrons remain stable in their orbits. This is because of the fact that electrons remain stable as long as they move in their specific orbits (energy levels). So, we conclude that Larmor's formula is true for practical purposes but false for situations at the quantum scale. hence it is not universally true.

 

Similarly, the change in time is almost unnoticable for real-life situations. But, the time dilation is quite substantial for speeds approachable to speed of light. Thus the Galilean relativity is perfect when velocity is very very less than c but is not true for high velocities, if v=90% of c. Hence this is too not a universal theory.

 

All theories depend upon their scale of reference. At a particular scale, a particular theory is consistent and applicable.

 

[Strange]

I get what you mean here. But then will you argue that if a theory is not falsifiable, meaning it can't be proved wrong, is not true?

 

 

Huh?

 

If it can't be falsified, then it isn't a (scientific) theory. So it doesn't mean it is wrong, just irrelevant.

 

A theory may be true to some but not true for all.

 

Indeed. Newtonian gravity is "falsified" by observations such as the degree of gravitational lensing, precession of Mercury, etc. But that doesn't mean the theory is wrong, just that it is not always applicable.

 

There are very few theories which are actually shown to be wrong, such that they are no longer used. Phlogiston is about the only one I can think of. Oh, and the Steady State Universe. And ...

[sethoflagos]

An old one, but worth repeating.

 

During a train trip through the countryside, an engineer, a physicist, and a mathematician observe a flock of sheep. The engineer remarks, "I see that the sheep in this region are white." The physicist offers a correction, "Some sheep in this region are white." And the mathematician responds, "In this region there exist sheep that are white on at least one side."

 

Mathematics is founded on absolute axioms (eg Euclid), and is therefore amenable to deductive reasoning.

 

Reality is not. Partly because we lack a 'theory of everything' in which to frame such axioms, and partly since it is unfeasible to subject every particle to in the universe to test to prove universality of an observation.

 

We do have axioms of a sort (the postulates of thermodynamics were mentioned recently in a similar context), but they remain essentially statistical rather than absolute. Various thermodynamic relationships may be deduced from the postulates, but the foundation remains empirical, and potentially open to reinterpretation.

Edited November 19, 2016 by sethoflagos

[jimmydasaint]

Hi who may concern,

 

We know that there are mainly two way inductive and deductive reasoning to prove a scientific theory. Inductive reasoning is proving something from observation and generalise it whereas deductive reasoning is another way round. Most of the law and theory are proved by using inductive reasoning. My question is that "is there any scientific theory proved by deductive reasoning?" Thank you.

First, of all, I cannot agree with the word "proved". IMHO, Scientific technique involves investigation of a broad hypothesis which has appeared from observations (which are repeated) of a certain phenomenon, e.g. electricity applied to a frog's leg make it contract. Experiments are then performed on the size of the potential difference until the threshold potential difference is known. Then the frog's muscle and neurons are examined to investigate how electrical events occur to make the muscle move, until a new hypothesis occurs.

 

Falsifiability of the hypothesis is the aim. This is all deductive. Much of scientific experimentation is deductive.

 

Where did you get the idea that all Laws are proved inductively? And how did you come to the idea that Science proves things, when there is no question of 100% proof?

 

I realise that language difficulties may be obscuring what you meant, so I don't mean to sound harsh. Please back up your OP with examples of what you mean.

Edited December 18, 2016 by jimmydasaint