Idola specus

Idola specus (singular Idolum specus), normally translated as "Idols of the Cave" (or "Idols of the Den"), is a type of logical fallacy whereby the peculiar biases of individuals lead them to errors. This Latin term was coined by Sir Francis Bacon and used in his "Novum Organum", one of the earliest treatises arguing the case for the logic and method of modern science. He described them as deriving from "the peculiar constitution, mental or bodily, of each individual; and also in education, habit, and accident".
Overview.
The "idola specus" are prejudices, by which individuals inappropriately extend norms or tenets that derive his or her own culture and social group, or to his or her own preferences. Racism, sexism and, more generally just "biases" are examples of "idola specus", but the concept goes beyond them to the criticism of all forms of irreflexive subjectivity or individual predisposition.
The term is one of four such "idols" which represent "idols and false notions which are now in possession of the human understanding, and have taken deep root therein, not only so beset men's minds that truth can hardly find entrance, but even after entrance is obtained, they will again in the very instauration of the sciences meet and trouble us, unless men being forewarned of the danger fortify themselves as far as may be against their assaults".
Besides "idola specus", there are also "idola tribus" (Idols of the Tribe, caused by human nature), "idola fori", (Idols of the Market Place, caused by language) and "idola theatri" (Idols of the Theatre, which are caused by the influence of philosophers).
In more detail, Bacon said that there are a "great number and variety" of idols of the cave but he choose to select example which give "the most important caution", and which "have most effect in disturbing the clearness of the understanding". He judged that they "grow for the most part either out of the predominance of a favorite subject, or out of an excessive tendency to compare or to distinguish, or out of partiality for particular ages, or out of the largeness or minuteness of the objects contemplated." Concerning these most important variants he wrote in more detail:
Bacon also drew general advice for more methodical future study of nature, aimed at avoiding the idols of the cave: "generally let every student of nature take this as a rule: that whatever his mind seizes and dwells upon with peculiar satisfaction is to be held in suspicion, and that so much the more care is to be taken in dealing with such questions to keep the understanding even and clear."