What fallacy is arguing from something being more X to it being completely X?

An example to illustrate:

The sea is more blue than the sky, so the sea is just blue, has no red etc.

It could be inductive, in which case I'm less sure that it is a fallacy. But the person in question is using it to ignore any evidence that the sea is also red.

  • 1
    "The fallacy of composition arises when one infers that something is true of the whole from the fact that it is true of some part of the whole", Wikipedia.
    – Conifold
    Aug 25, 2019 at 7:58
  • On my iPad, the quote in the question ends with “has no”. Aug 25, 2019 at 17:17
  • 1
    on my pc it ends "has no red etc." @MarkAndrews
    – user38026
    Aug 25, 2019 at 17:22
  • 1
    That was a hilarious exchange of words.
    – Joachim
    Sep 23, 2019 at 19:24

2 Answers 2


A fallacy is argument built from premises that are irrelevant, unacceptable, or otherwise fail to provide the grounds for the conclusion.

You argument can be rewritten:

P1: If something is more than something else, it is only that something.

P2: The sea is more blue than the sky.

C: So the sea is just blue.

It certainly is a fallacy, but I'd argue that this form of bad inference isn't categorized. There is no mention of parts and wholes, so it is not the fallacy of composition. I'd argue there is no label for this fallacy on account it doesn't appeal to the over one-hundred cognitive biases humans are liable to accept where a fallacy is an inference in reasoning that produces contradiction, and a bias is a means by which the human mind assigns certainty to a conclusion. These are subtle but important differences. For example, compare ad hominem with reactive devaluation.


The comparison between the sea and the sky suggests that an analogy is involved. One way for an analogy to be fallacious is for it to be a "weak" comparison.

Here is how Bo Bennett describes a weak analogy:

When an analogy is used to prove or disprove an argument, but the analogy is too dissimilar to be effective, that is, it is unlike the argument more than it is like the argument.

In this case arguing that the sea is blue by comparing it to the blue sky seems strong although there might be objects floating in the sea such as seaweed that suggest otherwise.

Bennett, B. "Weak Analogy". Retrieved on August 24, 2019 from Logically Fallacious at https://www.logicallyfallacious.com/tools/lp/Bo/LogicalFallacies/181/Weak-Analogy

  • surely not an argument from likeness, but disanalogy?
    – user38026
    Aug 24, 2019 at 15:43
  • @another_name Likeness I imagine would be covered by "analogy". If fallacious it would be a weak analogy, but this comparison seems OK. Aug 24, 2019 at 20:36

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