What is the Meaning & Definition of obviousness

He is considered that a claim is a no-brainer when any kind of explanation is not necessary because it is quite obvious. Something is obvious when it is absolutely clear and don't need any clarification.

Examples of platitudes

If someone says that in a job you have to strive or to touch you the lottery is a matter of luck, we have two truisms. These statements are, in some way, unnecessary, because they do not provide any complementary or interesting affirmation. Before them a partner cannot be in disagreement, since they are necessarily true.
The everyday use of language States that something is a no-brainer to indicate that it is a simple, i.e. information without any relevance. Sometimes says "this is obvious" to imply that it is accordingly (in this sense, is to say "of course").
When we communicate a series of synonyms can be used to replace the term obvious (clear or obvious would be the most common).

It seems a no-brainer not always is it

There are statements that are obvious; for example that the cakes have a sweet taste. However, other claims are regarded as something obvious, but this assessment is more debatable. Let's look at this case with two classic examples: the woman is the weaker sex and the Earth is the center of the universe. Both statements were understood as evident for centuries.

The evolution of the image of women and their struggle in equality with men

It was considered that women were inferior to men and, therefore, was the weaker sex by definition. This assessment has changed over time and is now considered a false statement, since the woman has demonstrated its strength in many ways. The idea that the Earth was the center of the universe was understood as something common sense for centuries and the change in valuation was very slow (the passage from the exclusivists to heliocentrism was a revolution). In conclusion, these simple examples show which is suitable to be cautious when assessing certain how obvious statements.
We must remember that some platitudes go unnoticed, something that can be seemingly contradictory. This idea can be illustrated with a classic example, the tale of the new clothes of the Emperor of Hans Christian Andersen. In this story, the Emperor's new clothes was a suit non-existent and only intelligent people could appreciate it.
Thus, when the Emperor left naked to show off her suit nobody dared to say that you going naked even though it was obvious. The obviousness that everyone saw, but no one dared to comment only discovered when a child dared to say with total naturalness that the emperor was naked.