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Comment by entangld | Hacker News Reader

Arithmetic is required to be logical? I doubt it.

Be logical? No. Make sense? Yes.

You can make all the navel-gazing syllogism you want with pure logic, but if you want to make conclusions about the real world then in many cases (like the domain under discussion) you're going to need to involve math.

So what you're saying is you could listen to someone and agree that what they're saying is logical but it doesn't make sense?

I'm not being a jerk, but could you please give me an example of something logical that doesn't make sense?

I'll try - to me, it's the difference between qualifying and quantifying. For instance, buying a new car when the one I own is facing serious problems is logical, but it may not make sense if I don't have the ability to pay for a new one. Math would be needed here to fully express that notion.

I don't want to get metaphysical here, but this is starting to meld into something a little too abstract.

An argument doesn't need to make perfect sense in order to make sense. With math you might try to make it perfect, but even mathematical projections can be guesswork. With a certain level of uncertainty, it's not about the math. And when you're looking toward the future, you're mostly using theories. Maybe the theories don't become clear until they've proven themselves, but we can still understand them, because you can have a reasonable amount of uncertainty and still make sense.

All noses are frozzle.

Some wiggles are noses.

Therefore, some wiggles are frozzle.

I'm not advocating fuzzy logic, just like the people who believe math is needed to make sense aren't advocating bad statistics.

Example: "We want to survive. Survival requires sustainability by definition. Therefore, we must have sustainability". True, but rather useless without going into what sustainability means numerically.

So one of my employees comes to me and says: assuming we can get widget X for a price of $y (or less), and do so consistently for time t, we can use some method to manfacture our frobulators, and still meet our price point, but get more long-term profit, because some TCO concerns. This is perfectly logical, but doesn't make sense given that the price of X this week is $y+1.

More complicated: if we know the price or X varies between $y+2 and $y-1 in a random walk, can we find a way to capitalize on the 50% of states that meet the $y or less requirement. My employee does not know the price characteristics for X, so he presents the idea. I know that we cannot capitalize (from doing analysis of the price of X based on doing the arithmetic). So what my employee suggests is completely logical and reasonable, it just makes no sense, given the result of the arithmetic.

Like in these videos? http://www.youtube.com/watch?v=F-QA2rkpBSY

Logic can be expressed mathematically, and you will be in a lot of trouble if you don't understand how it works... especially in programming.

I would argue arithmetic is founded in logic, not the reverse. It's foolish to believe mathematics are anything more natural than an invention predicated on logical notions.

I'm saying mathematics might be sufficient to express logic, but it ain't necessary.

Geez all the downvotes for a statement that isn't even controversial?

In cases like the article posted on the discussion of energy, it's hard to make cases without numbers. I admit that I hadn't read the article when I initially posted. I should also add that I didn't downvote your comment.

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