What is the name of this logical fallacy?

Question

It fallaciously reasons along the lines of "Bigger is always better".

Example 1:

Eating food makes you satisfied. Person A has eaten more food than Person B, therefore Person A will be "more satisfied" than Person B.

This could be fallacious because Person B's available food may be enough to completely satisfy her and any extra food (which is available to Person A) will be surplus and make no difference to their level of satisfaction.

Example 2:

Wearing shoes on hot coal stops your feet from getting burnt. Person A has more pairs of shoes than Person B, so Person A's feet will be less burnt than Person B.

In this case, as soon as someone has one pair of shoes, anything else (or surplus) has no effect.

Answer 1

I'm not sure that there's a name for the fallacies involved in your two examples. I'm also not sure it matters. Some fallacies get names because they are particularly common - for instance, denying the antecedent. But simply being able to recite a pat little name for some fallacy is not very useful in rational discourse. What's helpful is being able to identify instances of bad reasoning and being able to explain why they're bad. If you can do that, who cares if there's a name for that kind of bad reasoning?

For instance, in example 1 the inference (if it's intended as a deductive inference) is bad for the reason you identified. Who cares if we have a name for that failure? What do we gain with a name? My answer: not much.

Answer 2

Usage of adages like "Bigger is always better" in this way may be considered a faulty generalization, and more specifically a "thought-terminating cliche":

a commonly used phrase, sometimes passing as folk wisdom, used to quell cognitive dissonance, conceal lack of thought-entertainment, move on to other topics etc. but in any case, end the debate with a cliché—not a point

"List of fallacies". Wikipedia.

A second issue that you point to is not a fallacy, but a concept known as "diminishing return":

diminishing returns/ noun

1. Also called law of diminishing returns. Economics. the fact, often stated as a law or principle, that when any factor of production, as labor, is increased while other factors, as capital and land, are held constant in amount, the output per unit of the variable factor will eventually diminish.

2. any rate of profit, production, benefits, etc., that beyond a certain point fails to increase proportionately with added investment, effort, or skill.

~Dictionary.com

Definition 2, is more ambiguous and allows for broader application, to describe when the increase of some factor does not yield in a significant increase in the overall value (i.e. Wearing shoes on hot coal stops your feet from getting burnt. Person A has more pairs of shoes than Person B, so Person A's feet will be less burnt than Person B.). In Philosophy this idea has several applications; e.g. to contend with the concepts of maximization of Utilitarianism, or John Rawls's discussion of distribution related to Social Justice.