There is a particular fallacy I encounter often, and I don't know if it has a name already. I call it the salt in pasta water fallacy. In this post I will present the fallacy, discuss why I believe it is a fallacy, and give a concrete example of it happening. Salt in pasta water The archetypical example of the fallacy is the following claim: Adding salt to pasta water reduces cooking time. The proof for this statement can be described as follows: 1. When cooking pasta, the higher the temperature of the water, the lower the cooking time 2. The temperature of the water is its boiling point 3. Adding salt to water increases its boiling point 4. (3+2) Adding salt to water increases the temperature 5. (4+1) Adding salt to water decreases the cooking time "All of those points seem very reasonable", you may be wondering, "where is the fallacy?" Is there some sneaky chemistry phenomenon going on? AFAIK no, there is none. My objection goes a bit deeper. Let's do the math First of all, can we estimate how big the effect is? To do this, we need to know three things: * How does the temperature affect cooking time? I found a paper[1] from which I derive the following first-order approximation: each extra °C decreases the cooking time of 30 seconds. * How does salt affect the temperature? I found another paper[2] which claims that the boiling point is raised one degree for every mole of salt (i.e. for every 58g) per liter. * How much salt does one typically add to pasta water? This is more personal, but it seems that about 5g/l is standard So, now we simply multiply all of this and obtain... 2.6s. By adding salt to pasta water, one saves 2.6 seconds of cooking time. Where is the fallacy again? You may be wondering where I am going. The initial statement seemed true, I just added numbers, so what? Where is the fallacy. The fallacy, I claim, is that 2.6s are nothing. Adding salt does not decrease cooking time. It doesn't increase it either, it just does nothin