What fallacy is "Lots of things cause bad thing X, so there is no point in not doing Y to prevent X"?

Question

Paraphrasing from a real conversation:

A: Peanut butter causes cancer. So you should avoid it.
B: Pollution also causes cancer. Lots of things cause cancer. We can't avoid them, so there's no point in avoiding peanut butter.

I was left so gobsmacked I couldn't think of a reply, much less any kind of counterargument. I'm sure there must be something wrong with this argument, but I can't put my finger on what - it just seems obviously wrong but I can't explain why.

Is this some sort of fallacy? Can anyone tell me what it is? It's similar to the perfectionist fallacy, but somehow feels different to me.

Answer 1

Assuming the "peanut actually causes cancer" is true and the focus is on B: then B would have used Moral equivalence to misdirect attention from the original "problem" by saying "Pollution also causes cancer. Lots of things cause cancer.", trying to decreasing significance of the original statement. The part "We can't avoid them" is true however followed by "Non sequitur" (unrelated conclusion).

And for the sake of the argument as to the response. A: Its true lot of things cause cancer, we don't have control over. But we can choose if we eat peanut butter or not. Giving us the change to increase the risk of cancer or not.

Answer 2

Maybe think about it this way. B actually denies the inference, if there is any, from 'Peanut butter causes cancer' to 'you should avoid it'. Just because something causes cancer doesn't mean we should avoid it. Why? Well many things cause cancer, and it's not true of them that we should avoid them, so what makes peanut butter special?

I'm not saying it can't be argued that there is something that makes peanut butter special (maybe it's special in that it is very easy to avoid, and pollution isn't), but maybe this is what the objector had in mind. If it is, I don't see a fallacy here.