More to Less

[siyang1.wu]

Here is my question: If we know that more A leads to More B, is that sufficient to say Less A leads to less B? And does that hold in the opposite order? My reasoning is: let's say we are at A=100 and B = 100, and we know that it applies universally that more A leads to more B. So we can deduct that if A>100 then B>100. But consider that if A<100 but B not <100 so B>=100, we know that at least there is one case in which A increases without B increases(or even with B decreases). Therefore, we can prove that more A leads to more B<-> less A leads to less B. Is my logic sound here?

[tommywallach]

Hey Siyang,

In short, no.

Think of it this way. What if I have the perfect amount of sugar in a drink. If I add more, the drink gets less tasty, but if I take some away, the drink ALSO gets less tasty. See what I mean? There's no definitive reason why adding stuff makes something happen, but taking stuff away will thus make the opposite thing happen.

Make sense?

-t