Common Sense

Common sense refers to a kind of shared knowledge between members of a group that are deemed "basic" and expected to be known by its participants. Examples of things considered common sense are basic arithmetic, handling of every-day objects and (to autistic people's detriment) social functions/expected behaviour.

Some things that would be considered common sense, for example:

• (arithmetic) that 2 + 2 equals 4;
• (social behaviour) that you must say "Good morning" as a greeting while it's morning, but "Good afternoon" at the afternoon; At night you must use "Good evening" whenever you're entering a situation, and "Good night" when leaving;

Allistic people are naturally inclined (by virtue of their neurotype) to absorb and internalize socially expected ideas -- which is a great obstacle for autistic individuals.
When further investigating common sense as an autistic person, one finds it is not a "sense," nor is it "common"; it's merely an assemblance of propositions about the world that are shared within a community across time.

Usage of the term by allistics

'Common sense' is usually used to express a person who is "sensible" and "correct" (from the speaker's perspective) and has the basic 'knowledge' to 'function within society.' It also presents the idea of common sense being shared by the utmost majority and any deviation is subtly deemed wrong.

• Anyone with any common sense would have known what to do.
• Common sense and creativity are the essential qualities we need in an employee.
• I am sure that common sense will prevail in the end.
• There is no doubt that the court's decision is a victory for common sense.
• You get out first, and then lift the boxes out. Honestly - use your common sense!

Cambridge Dictionary: "common sense"

However, an idea which is called common sense does not imply it is fact.
Examples of non-factual common-sense ideas are: that being in the cold gets you sick, lightning never strikes the same place twice, that you would sink if jumping on lava, et cetera.

Disagreements regarding Common Sense

Furthermore, for something to be deemed common sense, in colloquial use, it needs not to be common (in both small and big scales).

In small scales, "common sense" will be used as a source by people, to express that a certain idea is taken by them as obvious and should not have needed to be explicitly said; often because of the false assumption that any knowledge the speaker has is also shared by other people.

In big scales, there will be communities with conflicting information about topics. For example, it is believed in some groups that vaccination causes Autism; while it's common sense in autistic communities the fact that it does not.
There is also a history of the idea of common sense being used against non-socially accepted identities (neurodivergent culture and behaviour, transgender people, non-binary identities and inclusive language, etc).

In summary, common sense is a heavily-relied-on tool for allistics to approximate knowledge which it is incredibly useful and intuitive, but it lacks the consistency, consensus and verifiability of other systems of deriving knowledge such as, for example, The Scientific Method.