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The Scientific Method - Induction, Deduction, Proof, Truth...


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Not sure I'm posting this in the right subforum or not, so please feel free to move this to a better spot.

 

Been getting fairly frustrated lately with the inconsistency of information regarding the scientific method, inductive reasoning, theory, hypothesis, proof vs. disproof...

 

I thought you guys gave me a pretty good handle on this back when I used to frequent this forum, but increasingly, I'm growing suspicious of what I believe. And Google searching is producing mixed results.

 

 

1) I thought is was clear that science creates hypotheses via induction - that we formulate ideas about how things work by observing phenomena and inferring broad principles. We cannot deduct because we must imagine and infer how things work, and then test our ideas.

 

We deduct when we use hypotheses to describe how things will behave - we apply those principles, or hypotheses.

 

So, induction to formulate hypotheses, and deduction to apply hypotheses. And I thought this was simply the natural state of affairs since we have no objective view of the universe or reality. We are inside the proverbial test box, so we are naturally limited to inductive reasoning. And this is why all theories and hypotheses are replaceable by better ones.

 

 

 

2) I thought science does not prove things. That when we test our hypotheses, we are testing to disprove, or to falsify never to prove or verify (going back to the inherent limit of induction). I thought there was no truth in science. That it doesn't matter if a hypothesis has been tested one million times and has failed to be falsified, that we cannot make the leap to "truth" and "proof" despite how small and insignificant the leap may be, as that would invoke "faith" and science doesn't use faith. There is no 100% verifiable truth. Again, this is why all theories and hypotheses are replaceable by better ones.

 

 

 

 

 

3) Finally, I thought theories were formulated by hypotheses. That we test numerous hypotheses, and then formulate a theory that uses them. That a theory is rigorously tested because it is made up of hypotheses that were rigorously tested.

 

 

These ideas and belief feel completely natural to me. What do I have right, and what do I have wrong?

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1) I thought is was clear that science creates hypotheses via induction - that we formulate ideas about how things work by observing phenomena and inferring broad principles. We cannot deduct because we must imagine and infer how things work, and then test our ideas.

 

We deduct when we use hypotheses to describe how things will behave - we apply those principles, or hypotheses.

 

So, induction to formulate hypotheses, and deduction to apply hypotheses. And I thought this was simply the natural state of affairs since we have no objective view of the universe or reality. We are inside the proverbial test box, so we are naturally limited to inductive reasoning. And this is why all theories and hypotheses are replaceable by better ones.

 

Yes, with a caveat that your hypothesis can lead you to a model, and analysis of that model to yield predictions can be deductive. i.e. the induction happened earlier in the process. You still have to test your predictions.

 

 

2) I thought science does not prove things. That when we test our hypotheses, we are testing to disprove, or to falsify never to prove or verify (going back to the inherent limit of induction). I thought there was no truth in science. That it doesn't matter if a hypothesis has been tested one million times and has failed to be falsified, that we cannot make the leap to "truth" and "proof" despite how small and insignificant the leap may be, as that would invoke "faith" and science doesn't use faith. There is no 100% verifiable truth. Again, this is why all theories and hypotheses are replaceable by better ones.

 

"Proof" can sometime be used (or misused) to mean that something was rigorously tested to falsify it, and it passed the tests, or a specific question was addressed. e.g. dropping an apple proves the existence of some attractive force between the apple and the earth. here, proves merely means demonstrates.

 

But in the strict sense, theories are not proven.

 

Testing gives us confidence that a theory is correct. After enough testing, one generally takes the theory as a given and can formulate hypotheses that extend beyond it. e.g. it has long been true that one can take conservation of energy or momentum as true, and not independently confirm that as part of an experiment.

 

3) Finally, I thought theories were formulated by hypotheses. That we test numerous hypotheses, and then formulate a theory that uses them. That a theory is rigorously tested because it is made up of hypotheses that were rigorously tested.

 

Theories are the collection of equations/laws, the concepts that tie them together and the evidence that supports it. When one refers to e.g. the theory of special relativity, it encompasses length contraction, time dilation, simultaneity, clock synchronization, mass-energy equivalence and more, and all of those experiments that show SR to be correct, because (depending on context) any part of that might be under discussion.

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Science deals with universally quantified statements, and as such, you're correct that it relies on induction. No one data point can give you a universal. In order to verify a universal, you'd need to verify every single instance ever. And that's just not doable in the overwhelming majority of the cases. What is easier (and, is sometimes inaccurately portrayed as the only thing [thanks mainly to Karl Popper]) is to show which universal statements are false.

 

Science doesn't care about how you come up with an idea, but rather, how you justify it. In philosophy terms, it's about the justification side of the justification-discovery distinction. While what is and is not science has changed dramatically since science first started, modern science is more or less defined by Ruse's criteria:

  • A scientific theory makes predictions
  • A scientific theory is testable [which requires (1)]
  • A scientific theory is tenable [it is open to being overturned]
That's not exactly how he presented them, but many of the criteria collapse in on each other. For example, (1) and (2) are very nearly the same thing.

 

The scientific method is inductive as mentioned earlier, but it is also deductive. When you test a hypothesis, two things happen. The solely inductive bit is confirmation. If it passes the test, its probability of being true goes up.

 

The other thing is a mix between deductive and inductive. Falsification, ideally, is a simple example of Modus Tollens.

 

If p, then q.

It is not the case that q.

Therefore, it is not the case that p.

 

The problem with this (called the Quine-Duhem problem) is that you can almost never test p by itself. Any test is going to rely on multiple theoretical aspects and some environmental factors. So, the Modus Tollens becomes:

 

If l and m and n and o and p, then q.

It is not the case that q.

Therefore it is not the case that l and m and n and o and q.

 

The thing is, that just tells us that they can't all be true. It doesn't tell us which one [or ones] is false. That's where the induction comes in. We can use the probability calculus to tell which bits are less likely to be true after a falsifying test.

 

As far as proof goes, they are both ironclad proof, but you have to be careful at making sure you know what you're proving. Falsification proves that at least one of the entangled hypotheses and assumptions is false. Confirmation proves that a theory is more likely to be correct.

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  • 3 weeks later...

String Theory as applicable to physics should be mentioned. IMO. It is a confusing name. I believe the same is true of M-theory, F-theory, and a few other theories. See: Should science drop the word 'theory' out of its vocabulary?

 

Given this caveat, I agree with the previous posts in this thread that define of hypothesis and theory. Languages change, and we must adapt.

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Scientists are highly trained in the practice of science. They receive minimal training in the nature of what it is they do. The excellent outline you provided and that swansont expanded upon is, I suggest1, a simplification that circumvents the unpleasant task at actually looking at how things are done. This is because science is practiced by human beings, not idealised scientists. This is not a problem unless one attempts to base ones arguments upon this idealised description.

 

1. I say suggest as an act of British understatement. I mean "I'm jolly well certain".

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  • 4 weeks later...

 

1) I thought is was clear that science creates hypotheses via induction - that we formulate ideas about how things work by observing phenomena and inferring broad principles. We cannot deduct because we must imagine and infer how things work, and then test our ideas.

 

We deduct when we use hypotheses to describe how things will behave - we apply those principles, or hypotheses.

 

So, induction to formulate hypotheses, and deduction to apply hypotheses. And I thought this was simply the natural state of affairs since we have no objective view of the universe or reality. We are inside the proverbial test box, so we are naturally limited to inductive reasoning. And this is why all theories and hypotheses are replaceable by better ones.

 

Aristotle noticed what he called natural order and what he termed Gravity was the natural order of the tendency of things to fall. Gravity as a idea proposed by Aristotle developed over two thousand years through Newton and to Einstein's relativity theory of gravity. I understand what you are saying if you take Aristotle's original idea of Gravity and attribute it as an induced idea from his observation. However when the idea of gravity was studied through science "gravity" theory was deduced. So "yes" induction in the broadest epistemological sense is the spark for an idea like gravity but the theory is logically deduced and logically tested. So scientific theory is logically deductive. On the other hand Quantum Mechanics was induced from the data measurements of the atom like the Bohr atom. There was no quantum theoretical idea that was proven logically. Nobody has called QM logical but it does have internal consistency the requires 22 adjustments that are logically not deduced but induced to create an outcome for QM to stay inline to experimental results. Gravity started as a theory and still is a theory through logical deduction. QM started as a logically induced construct and is still a logical construct but QM is not a theory. It is clearer in my mind to keep context in mind when a word is used. The idea of gravity can be attributed to induction but everything we are aware of is induced through our senses. Science is a deductive process whereas technology is induced. QM is a tool for the theoretical scientist to propose outcomes that experimental scientist can test which technicians then apply based on experimental results to new technology. QM is a great science and hugely valuable in general but it is not a theory - and that is worth understanding. QM creates answers but not understanding.

 

I understand what you are saying and agree within the context of your statement. Hope I have added something useful. I do not think Aristotle formulated gravity but just defined it. Newton formulated gravity from Aristotle's idea. Newton created the theory of gravity from the idea of gravity.

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