In its 引用（いんよう） ‘citation’ usage, the 格助詞（かくじょし） (case-marking particle) と
is often used with verbs in the passive
form. Two of these regularly occurring verbs are 考（かんが）えられている
‘to be considered’, and 思（おも）われている
‘to be thought’.
This grammar point is used after a phrase, and translates as ‘it is considered that (A)’, or ‘it is thought that (A)’. It is generally used to highlight a commonly held opinion that most people agree on (not your personal opinion).
Shimura Ken is considered to be the first person who said ‘saisho wa gu’. (A phrase said before playing rock, paper, scissors, in Japan)
This tunnel is thought to be one of the most cursed tunnels in Japan.
The primary reason that these constructions are used in their displacement (passive
) form, is to show that the thought itself is not something that is related to the speaker's own opinions.
However, people will often use this form as a way to strengthen their own opinions, in a similar way to how English speakers would say ‘everyone knows that (A)’.