Logic vs. Observation

[SVPD]

Okay, question:

Are there instances where what is logical contradicts what is observed?

For example:

Someone put this case forth on another board

"We know gravity exists because objects fall to the ground, whivh they do because of gravity."

He claimed that you couldn't logically prove the existance of gravity.

However, we know that objects fall tothe ground and they won't suddeny stop doing so because the proof of gravity is circular.

So, are there instances where formal rules of logic contradict what the facts actually are?

[Darth Wong]

Of course you can't logically prove the existence of gravity; the concept of gravity is a hypothesis which is used to explain certain observations.

However, differentiating between the facts and the only explanation of those facts that makes any sense is hair-splitting on his part. The facts (in the case of gravity) are innumerable observations of objects being attracted to a much larger object (namely, this planet) when released. Gravity is the only explanation that makes any sense. The fact that you can't "logically prove" this explanation is irrelevant if one understands how the scientific method works.

Of course, it's possible that he's planning to throw Hume and then solipsism at you, as many anti-science types are wont to do. If that happens, then you have to use the stock anti-Hume and anti-solipsist arguments.

Ultimately, it's tiresome to deal with people who reject the entire scientific method. Their goofy alternate philosophical worldviews are utterly useless, and it bears noting that if the developed world had employed their methods rather than the scientific method over the last 400 years, it would not be the developed world today.

[Surlethe]

He claimed that you couldn't logically prove the existance of gravity.

Here. I'll do it with mathematics, which ought to be logical enough for him.

Null hypothesis: the proportion of objects which fall to the ground at 9.8 m/s/s is 1/2 (assuming to maximize probability).

Alternative hypothesis: the proportion of objects which fall to the ground at 9.8 m/s/s is greater than 1/2.

Dropping something is a Bernoulli process, so I test my null hypothesis by dropping ... and dropping ... and, I'll be damned! After ten thousand tests, they've all fallen at 9.8 m/s/s! The probability of that occurring randomly is so incredibly small it practically doesn't exist; therefore, something is causing the objects to drop at 9.8 m/s/s. We like to call that something "gravity".

In fact, you can generalize this experiment to include every single observation of celestial mechanics. They all point to the existence of some attractive force which is testable, quantifiable, and behaves consistently and rationally.

So, are there instances where formal rules of logic contradict what the facts actually are?

Just a priori, I wouldn't think so; one of the basic assumptions about the universe is that it's logically consistent, so any observations which contradict formal logic would be discarded as nonsensical before they leave the laboratory.

EDIT: spelling

[SVPD]

Just a priori, I wouldn't think so; one of the basic assumptions about the universe is that it's logically consistent, so any observations which contradict formal logic would be discarded as nonsensical before they leave the laboratory.

Wouldn't that violate the scientific method?

[Flagg]

Okay, question:

Are there instances where what is logical contradicts what is observed?

For example:

Someone put this case forth on another board

"We know gravity exists because objects fall to the ground, whivh they do because of gravity."

He claimed that you couldn't logically prove the existance of gravity.

However, we know that objects fall tothe ground and they won't suddeny stop doing so because the proof of gravity is circular.

So, are there instances where formal rules of logic contradict what the facts actually are?

Wait, isn't gravity a plot by the Jews to collect loose change?

Seriously, this guy sounds like a hairsplitter/derailer. By the time you realize just how off topic the guy has made tthe thread with his hairsplitting and ultra technical analysis of every little mundane subpoint everyone is sick of the argument and the thread effectively dies.

[Surlethe]

Just a priori, I wouldn't think so; one of the basic assumptions about the universe is that it's logically consistent, so any observations which contradict formal logic would be discarded as nonsensical before they leave the laboratory.

Wouldn't that violate the scientific method?

I don't think so; the point I was making was that any observations which appear to contradict logic and can't be rationalized would be discarded as flawed. I don't think I was too clear about that; sorry.

[Gil Hamilton]

Anyone who throws Hume at you in a debate isn't worth talking to, because you've already won. The Hume Card basically states "You can't entirely logically PROVE causality, so everything is faith", in other words, all bets are off and rational discussion of anything is impossible. It's the philosophical equivlent of taking your ball and going home when you are losing. Only pussies play the Hume Card in a debate.

[Patrick Degan]

Anyone who throws Hume at you in a debate isn't worth talking to, because you've already won. The Hume Card basically states "You can't entirely logically PROVE causality, so everything is faith"

That's the point where you invite him to jump off a building to test his faith in solipsism.

[Vendetta]

Wouldn't that violate the scientific method?

I don't think so; the point I was making was that any observations which appear to contradict logic and can't be rationalized would be discarded as flawed. I don't think I was too clear about that; sorry.[/quote]

No, that is quite the wrong way around.

Observations that appear to contradict logical expectations are re-examined, and if found to be accurate, form the basis of a new hypothesis.

For example, logically one expects that if you measure the speed of a moving object from a position that is also moving (eg. a moving vehicle), the observed speed should be the sum of the two speeds of the object and observer (allowing for vectors of movement, etc).

If the object whose speed is being measured is a photon, the observation will not meet the logical expectation. The speed measured will be the same whether the observer is moving or still.

If you throw that observation out because you weren't expecting it, some other clever bugger will come up with the Theory of Relativity instead of you.

[Surlethe]

I don't think so; the point I was making was that any observations which appear to contradict logic and can't be rationalized would be discarded as flawed. I don't think I was too clear about that; sorry.

No, that is quite the wrong way around.

Observations that appear to contradict logical expectations are re-examined, and if found to be accurate, form the basis of a new hypothesis.

For example, logically one expects that if you measure the speed of a moving object from a position that is also moving (eg. a moving vehicle), the observed speed should be the sum of the two speeds of the object and observer (allowing for vectors of movement, etc).

If the object whose speed is being measured is a photon, the observation will not meet the logical expectation. The speed measured will be the same whether the observer is moving or still.

If you throw that observation out because you weren't expecting it, some other clever bugger will come up with the Theory of Relativity instead of you.

This is all correct, but is beside the point; I wasn't trying to say we should throw out observations because we don't expect them. You're equivocating between logic and logical expectations: my point is that since it's impossible to contradict logic itself, then observations which do just that must be flawed somewhere, just as an omnipotent God can't exist. I agree we shouldn't throw out observations based on what we logically expect, but should that extend to not throwing out observations which are logically impossible?

[Vendetta]

Remember that your logical deductions about what is and is not possible are only as good as the premises you base them on.

If your observations are logically "impossible", but are repeatedy verified, then you need to re-examine your premises. (see previous example about relativity, it seems logically "impossible" that the speed light moves at relative to an observer is always the same irrespective of the observer's own velocity, but it happens to be the case)

Logic is a tool, and like with most tools, If you start with the wrong raw materials, you will get the wrong results, even if you use the tool perfectly.

[Surlethe]

Right. I guess that's why I couldn't manage to think of some even far-fetched examples where observations contradicted logic, as opposed to being able to rationalize them by changing premises: I was thinking of logic as only an output, rather than a tool with inputs and outputs. Thank you for the correction.

[Darth Wong]

Anyone who throws Hume at you in a debate isn't worth talking to, because you've already won. The Hume Card basically states "You can't entirely logically PROVE causality, so everything is faith", in other words, all bets are off and rational discussion of anything is impossible. It's the philosophical equivlent of taking your ball and going home when you are losing. Only pussies play the Hume Card in a debate.

I usually point out that Hume said it's illogical to think the Sun will rise in the East tomorrow. If someone has to resort to Hume's worldview in order to attack science (thus ignoring Popper and other flaws in Hume's argument), then it means that the credibility of science is "only" as good as the credibility of the Sun rising in the East tomorrow, and that's pretty good.