# Question about inductive and deductive arguments in science

• B
• Chenkel
In summary: Science is based on a combination of reasoning inductive reasoning to formulate hypothesis, and deductive reasoning to apply a theory to a specific situation. The "deductive" part of science is actually inductive because it is based on previous observations. So, in summary, you are saying that the "deductive" part of science is actually inductive?Yes, I believe that is what I'm saying.
Chenkel
TL;DR Summary
I've been reading about inductive, and deductive reasoning as they apply to science, and I came to a point where I have a question about the standard methods.
Hello everyone!

I have a question about a potential flaw I see in the scientific method, but I hope people will illuminate me, and convince me that science has no problem in the respect I might lament on.

What if a scientific premise in a deductive argument is based on an observation, and we are unsure about the accuracy of the observation?

For example:

Premise A (observation): All my pets are the same animal.

Premise B (observation): One of my pets is a cat.

Conclusion: Therefore all my pets are cats.

How can we be sure that we are using deduction flawlessly in this case? What if our eyes are not showing us the true reality, i.e is it possible that our observation could be flawed in some fundamental respect?

Science is based on a combination of reasoning inductive reasoning to formulate hypothesis, and deductive reasoning to apply a theory to a specific situation.

How can we be sure that the deductive part of science is bulletproof in its soundness if we can't be sure our observations are correct?

Let me know what you think, thank you!

That type of logical reasoning is often not needed.

Consider Newton's apple tree. He observed that the apples always fall down, and that the down direction was toward the center of the Earth, both in England, and in New Zealand on the far side of the globe. He then found theories that conform to those facts, and his theories were used to make predictions, that have been verified by subsequent experiments.

That evolution is not just the application of formal logic. In fact, the words true and false do not apply. We know that Newton's Laws correctly the describe some everyday physics, but relativity is needed for some cases on different scales.

The following PF Insight article explains why Einstein's theories do not make Newton's Theories wrong. Indeed, why true and false are the wrong words to apply to these theories.

https://www.physicsforums.com/insights/classical-physics-is-wrong-fallacy/

vanhees71, dlgoff, Dale and 2 others
Also there are no truths in science. Scientific method cannot prove something true. One can only prove a proposed counterexample false.
Do you feel better or worse?

hutchphd said:
Also there are no truths in science. Scientific method cannot prove something true. One can only prove a proposed counterexample false.
Do you feel better or worse?
I'm trying to understand, couldn't you argue that you're proving the proposition "the counter example is false" is true? If it's based on observation, how do you know you've proven the counter example false?

Chenkel said:
TL;DR Summary: I've been reading about inductive, and deductive reasoning as they apply to science, and I came to a point where I have a question about the standard methods.

How can we be sure that the deductive part of science is bulletproof in its soundness if we can't be sure our observations are correct?
We cannot be sure.

But we can be confident.

Nugatory, hutchphd, PeroK and 1 other person
Chenkel said:
I'm trying to understand, couldn't you argue that you're proving the proposition "the counter example is false" is true? If it's based on observation, how do you know you've proven the counter example false?
Me:The sky is generally blue.
Fool: this morning it was polka dot
Me: Here is camera footage for this morning of the sky. No polka dots

Me: Bumble bees cannot fly.
Bumble: Buzz
Me: oops back to the drawing board

Chenkel
hutchphd said:
Me:The sky is generally blue.
Fool: this morning it was polka dot
Me: Here is camera footage for this morning of the sky. No polka dots

Me: Bumble bees cannot fly.
Bumble: Buzz
Me: oops back to the drawing board
I believe you're not proving anything true or false with your example, science is only as good as the observation based on what I've read, am I wrong?

The observation of the bumble bee flying could be a magic trick. I do agree that bumble bees fly in my experience, but it depends on how confident I am in my observation.

Science is not perfect unless the observation is perfect.

Chenkel said:
The observation of the bumble bee flying could be a magic trick.
Don’t go there. This thread will be shut down with prejudice if you do.

Chenkel said:
Science is not perfect unless the observation is perfect.
I have edited the quote to correct it

hutchphd
Chenkel said:
I believe you're not proving anything true or false with your example
You seem to think that truths in science are absolute.

Causality is the law that says the cause must come before the effect. Never in history have we seen a counter example. Still, we have not seen the entire future yet. So the best we can say is that causality has never been violated in our experience.

hutchphd
Is the "deductive" part of science truly "deductive"?

Based on what I've read you can't "prove" anything true in science, so you can't "prove" anything false in science, all you can do is make "deductive" claims with perceived "observations." I am not going to talk about what an observation is, because I've already been warned it's a philosophical discussion, and philosophy is off limits on physics forums.

Chenkel said:
Is the "deductive" part of science truly "deductive"?
Yes. It is. Deduction always begins from some premises. That is unchanged in science.

Dale said:
Yes. It is. Deduction always begins from some premises. That is unchanged in science.
Without getting into a conversation of what an observation is, I will say that (based on my understanding which may be wrong.) observations can form the premises of a deductive argument, but only if we are a hundred percent sure that the observations are correct.

There is a sort of confidence that scientists have in their own sanity, that their observations are as precise as their reasoning skills with platonic logic, I won't take that away from them, I like to believe I'm living in reality too, and why shouldn't we believe this is true?

We, as scientists, must be living in reality with our observations, because all evidence leads to the fact that, if we were deluded, we would know, because we would suffer the consequences.

In science, as you said, we can be confident, I would go so far to say that this confidence is based on a mutually agreed upon sanity that we have with other scientists, that we all observe non violations of our working theories, and the violation of false hypothesis, to show what is consistent with agreed upon reality.

In my view, I'm very sane in saying we should be confident if we can perform the same experiment and get the same result over and over.

I don't think we disagree.

Chenkel said:
observations can form the premises of a deductive argument, but only if we are a hundred percent sure that the observations are correct.
You don’t have to be certain of the premises of a deductive argument. In fact, you can actively disbelieve the premises of a deductive argument. You often use premises that you disbelieve in a proof by contradiction.

Last edited:
nasu and Chenkel
Dale said:
You don’t have to be certain of the premises of a deductive argument. In fact, you can actively disbelieve the premises of a deductive argument.
I believe you are correct.

After researching, I found a precise philosophical definition on what a "sound deductive argument" is from the "Internet Encyclopedia of Philosophy". I believe it's relevant to the scientific method, and I can post it if you want.

Dale
Chenkel said:
I believe you are correct.

After researching, I found a precise philosophical definition on what a "sound deductive argument" is from the "Internet Encyclopedia of Philosophy". I believe it's relevant to the scientific method, and I can post it if you want.
The reason I ask is that I feel even though it's a definition from a philosophy site, it's most likely also the definition used by the physics community.

Chenkel said:
observations can form the premises of a deductive argument, but only if we are a hundred percent sure that the observations are correct.
You are again supposing that we are only seeking absolute truth. I think that a fool's errand but not all believe it so. The ediface of science is a structure of patches and rebuilds and occasionally dazzling architecture. It is eclectic and impure and makes our lives better.
The other powerful aspect of the scientific method is that you do no have to be ordained to claim special knowledge. Do not misunderstand me: scientists are as tribal as any other humans, but not doctrinally so.
Any scientific hypothesis (in my use) must be falsifiable and hence the lack of contradiction has real meaning. Any other supposition is just an idle musing, no better or worse than any other idle musing.

Vanadium 50, PeroK, Dale and 1 other person
I agree that it is a fool's errand, but for another (in addition) reason.

Philosophers of science seem to think that the input is a consistent set of facts. That's almost never the case. Measurements can be contradictory, or incomplete, or improperly analyzed, or miss an effect or be just plain wrong. The idea that everybody believed X until Measurement Y came along and then everybody believed Z is a gross oversimplification.

vanhees71 and Dale
This is a bigger problem and more common than is often appreciated

vanhees71
hutchphd said:
You are again supposing that we are only seeking absolute truth. I think that a fool's errand but not all believe it so. The ediface of science is a structure of patches and rebuilds and occasionally dazzling architecture. It is eclectic and impure and makes our lives better.
The other powerful aspect of the scientific method is that you do no have to be ordained to claim special knowledge. Do not misunderstand me: scientists are as tribal as any other humans, but not doctrinally so.
Any scientific hypothesis (in my use) must be falsifiable and hence the lack of contradiction has real meaning. Any other supposition is just an idle musing, no better or worse than any other idle musing.
From Wikipedia: "Established scientific theories have withstood rigorous scrutiny and embody scientific knowledge."

So a scientific theory has a falsifiable claim, and based on that falsifiability, we can rigorously scrutinize it under testing; a theory that has withstood rigorous scrutiny embodies "scientific knowledge."

So after all this analysis, what does the "scientific knowledge" tell us?

When can a scientist says that he "knows" something, what is that something that he "knows"?

Is the "scientific know" always based on deduction and an observation?

Is it a no no for a scientists to say he "knows" if he's using induction?

For the example, is it induction to say:

"All objects fall on earth"

"Therefore, if I throw this book out the window it will fall."

I guess what I'm asking is, based on a scientist having "scientific knowledge," does he know what will happen, what has happened, or both?

The Particle Data Group publshes "history plots", so one can see how measurements evolve. For example:

The "jumps" are caused ny new techniques.

vanhees71, berkeman and Dale
Chenkel said:
Science is not perfect
Who said it is perfect?

Chenkel
The very act of mature thinking seems to utilize scientific methods.

Chenkel said:
When can a scientist says that he "knows" something, what is that something that he "knows"?
I've come to a red light thousands of times in my life driving a variety of different cars. I press the brakes and I "know" that I will be able to stop within an adequate distance.

Various manufacturers, mechanics, actuaries and lawmakers have worked together to provide an assurance on which I can rely in these sorts of circumstances. In addition to my personal experience.

You might question the reliability of this sort of "knowledge". Yet we all routinely bet our lives on it.

This is quite similar to the sort of knowledge a scientist has. Except that a scientist may have actually examined the brake mechanism.

vanhees71, Ibix and Chenkel
Chenkel said:
I guess what I'm asking is, based on a scientist having "scientific knowledge," does he know what will happen, what has happened, or both?
Science is a method.
"Scientific knowledge" is an oxymoron. It may be falsely true or truly false.
As a human we choose that what we wish to call fact. For instance, some would tell us that God is a fact.
As a society we make collective decisions about such things. Hopefully we use science as our touchstone. This is why, IMHO, the USA has prospered enormously, at least until recently..

malawi_glenn
hutchphd said:
"Scientific knowledge" is an oxymoron. It may be falsely true or truly false.
I'm trying to understand that sentence.

Until one has performed every possibly salient experiment there is no certain knowledge. This has not and will not be done.

hutchphd said:
Until one has performed every possibly salient experiment there is no certain knowledge. This has not and will not be done.
If I never did a mathematical proof, or never performed an experiment, I would not "know" based on observations of others.

Maybe I'm wrong, but there should be knowable things that can be learned through everyday experience, and there are scientific things, "scientific knowledge" if I'm not mistaken, should be the intersection of the two.

For example, I bake a cake, I "know" from experience that adding more sugar makes it sweeter, the science experiment is baking the cake and enjoying it, the knowledge is as real as the dissatisfaction if I'm wrong.

Chenkel said:
For example, I bake a cake, I "know" from experience that adding more sugar makes it sweeter,
But will that be the case tomorrow? How do you know?

For example, my father in law had a course of crazy-strong antibiotics due to a serious infection. His sense of taste changed - everything tasted like cardboard, he said, for a week. So there's a hidden assumption in your thinking here, that your mouth flora didn't get massacred as colateral damage in a chemical attack on other bacteria.

Ibix said:
But will that be the case tomorrow? How do you know?

For example, my father in law had a course of crazy-strong antibiotics due to a serious infection. His sense of taste changed - everything tasted like cardboard, he said, for a week. So there's a hidden assumption in your thinking here, that your mouth flora didn't get massacred as colateral damage in a chemical attack on other bacteria.
That's a good point.

Your father is applying the scientific method to discover and "know" his taste is off, if he couldn't try to taste anything he would have not any experiment to perform, but because he can try to taste, he can discover that he does not taste very well; the knowledge that he does not taste well is as real as his dissatisfaction, I'd imagine not having taste can considerably reduce quality of life. I hope your father is doing better after that infection.

Ibix
Father in law. The loss of taste only lasted a week, but he didn't eat a lot for that week, no.

I gather your sense of taste has more to do with the bacteria living in your mouth than you might like to think, and loss of taste or even changed taste is quite a common side effect of high-dose antibiotics. My point was simply that your experience (more sugar = sweeter) has hidden assumptions. Scientific thinking seeks to tease out its assumptions and put them upfront, separate from deductions we make from those assumptions. But you can always find there was an assumption that you didn't know you were making - like your sense of taste being immutable, or time being an absolute, shared concept.

Chenkel
Ibix said:
Father in law. The loss of taste only lasted a week, but he didn't eat a lot for that week, no.

I gather your sense of taste has more to do with the bacteria living in your mouth than you might like to think, and loss of taste or even changed taste is quite a common side effect of high-dose antibiotics. My point was simply that your experience (more sugar = sweeter) has hidden assumptions. Scientific thinking seeks to tease out its assumptions and put them upfront, separate from deductions we make from those assumptions. But you can always find there was an assumption that you didn't know you were making - like your sense of taste being immutable, or time being an absolute, shared concept.
You make a valid point.

I would say knowledge of one's own suffering is very real, the most real.

If there was one last man on earth, he could still practice the scientific method.

If I was the last person on Earth and I kept putting my hand into a fire, I could conclude from the experiment that the longer I hold my hand in the flame, the more intense the pain.

Each second I have it in the flame I have "certain scientific knowledge" that this is a painful experiment.

Chenkel said:
here should be knowable things that can be learned through everyday experience, and there are scientific things, "scientific knowledge" if I'm not mistaken, should be the intersection of the two.
I do not agree. It is a false dichotomy. Both are examples of learning from experience.

Many things that "should" be so turn out not to be so. Good people should live forever. True love should never die. Justice should prevail. Unwise wagers should never pay off. Experiments should always yield correct results. Intelligent people should never reason incorrectly. One should not need to explain such things.

[Sorry, but it is a bit of a pet peeve. Too often a user will complain to me about what a program "should" do while I am working to understand and explain what it does do. "Should" butters no parsnips.]

Chenkel said:
So after all this analysis, what does the "scientific knowledge" tell us?
How to build stuff and how to do stuff. Like how to build a moon ship and how to fly it to the moon and back. Or how to build a fish bowl and how to keep fish alive in that bowl.

The value of scientific knowledge lies in its utility.

vanhees71, hutchphd, anorlunda and 1 other person
Chenkel said:
You make a valid point.

I would say knowledge of one's own suffering is very real, the most real.

If there was one last man on earth, he could still practice the scientific method.

If I was the last person on Earth and I kept putting my hand into a fire, I could conclude from the experiment that the longer I hold my hand in the flame, the more intense the pain.

Each second I have it in the flame I have "certain scientific knowledge" that this is a painful experiment.
YouTube recently served up this gem from the BBC of Hilary Putnam, a professor of the philosophy of science, taking about the scientific method. I'm just watching it over breakfast.

It seems to me that if you are interested in the philosophy of science, you should study it properly, rather than engage in unstructured personal philosophising:

hutchphd

## 1. What is the difference between inductive and deductive arguments in science?

Inductive arguments in science involve making generalizations or predictions based on specific observations or data. This type of reasoning moves from specific instances to a broader conclusion. On the other hand, deductive arguments in science involve starting with a general principle or theory and using logical reasoning to reach a specific conclusion. This type of reasoning moves from a broad statement to a specific prediction or observation.

## 2. Which type of argument is more commonly used in science?

Both inductive and deductive arguments are commonly used in science, but the type of argument used depends on the specific research question or problem being investigated. Inductive arguments are often used in exploratory or descriptive studies, while deductive arguments are more commonly used in hypothesis-driven studies.

## 3. How do inductive and deductive arguments contribute to the scientific method?

Inductive and deductive arguments are both important components of the scientific method. Inductive arguments help scientists generate hypotheses and make predictions based on observations and data. Deductive arguments help scientists test these hypotheses and theories through experiments and observations, leading to the development of new knowledge and understanding.

## 4. Can inductive and deductive arguments be used together in scientific research?

Yes, inductive and deductive arguments can be used together in scientific research. In fact, many scientific studies involve a combination of both types of reasoning. For example, a scientist may use inductive reasoning to generate a hypothesis, and then use deductive reasoning to design an experiment to test that hypothesis.

## 5. What are some potential limitations of using inductive and deductive arguments in science?

One limitation of inductive arguments is that they can lead to generalizations that are not always accurate or reliable. This is because inductive reasoning relies on making assumptions based on a limited set of observations. On the other hand, deductive arguments can be limited by the accuracy of the initial premise or theory. If the premise is incorrect, the conclusion will also be incorrect. Additionally, both types of arguments can be influenced by personal biases and assumptions, which can affect the validity of the conclusions drawn.

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