The roles served by communication, information and reasoning are primarily social. That is, these acts/events are primarily about getting on in groups and orienting the person in the world in relation to others, with whom they ally, and against others who are perceived as threats. Accuracy is secondary.
1) Ideas don’t have to be accurate to be accepted
For example, people believe in ‘free market’ economics despite the fact that it has never delivered the general prosperity, liberty or virtue, it has been used to promise. It may deliver wealth and power to the corporate elites but that is another matter. Lots of ideas/actions do not deliver, or even produce the opposite result to what is promised for them, but people fiercely defend them anyway.
Acceptance has nothing to do with the ‘accuracy’ of the idea, or their ability to deliver promised results.
2) Sharing ideas is about group bonding
What a set of ideas needs for it to gain influence, is to produce (or be associated with), social bonding and a sense of identity.
Any group bonding process is boosted by working together, or by specifying some other groups, or set of groups, as an enemy outgroup from which the group needs to be distinguished or defended – socialists, liberals, Muslims, Christians, capitalists etc…
It is not necessary that the favoured outgroup actually does attack the ingroup; all that is necessary is for the group’s ideas to frame the outgroup as an attacking force. This will help the sense of ‘working together’ in the ingroup and, eventually, one sided hostility will promoted the desired reprisals.
For example, Scientology provides a close bonding organization which claims to represent an elite (you in potentia), with a strong sense of being persecuted by evil outgroups, as well as a set of ideas which may or may not deliver, but which a person’s adherence to, defines them as members of the group.
Sometimes inaccurate ideas can give more of a sense of identity than accurate ones, particularly if the groups are driven by a sense of resistance to groups which profess more accurate ideas – for example climate change denial.
3) The group is marked by the ideas it promotes
The group, as marked by the ideas, provides support and social bonding, so that people have loyalties to fellow ingroup members, beyond loyalties to outgroup members (although this can be complicated). They also have loyalties to group ideas which symbolise the group’s loyalties. The ideas are more like flags of allegiance than tools to help understand the world.
Attacking and defending these ‘flagging’ ideas is often seen as the same as attacking or defending both the group that promotes them and the sense of identity and bonding it provides. Attacking ideas can appear to be an attack on the self, its social position, its associates, and its right to exist.
Ingroup members support each other in attack those who attack the ideas of the group. This states the virtue of the group, and further cements the bonds of loyalty and working together, thus reinforcing the ideas, irrespective of whether the ideas are shown to be accurate or not.
4) Identity is about loyalty and opposition between categories.
As implied, the identity provided by the group is often partly provided by its distinction from other groups.
Men are not supposed to be like women or vice versa, Muslims are not supposed to be like Christians and so on. Being-not-the-relevant-other is important to many (but not all) human groups or identity categories.
Furthermore a person can see the differences between fellow ingroup members with greater ease than they see differences between outgroup members. The type of attention applied is different. It is easier to believe all Republicans are the same, if you are not a Republican. Outgroups tend to be perceived as uniform and less human.
Some groups claim that eventually, all good hearted people, will be like them. Therefore people who resist them are clearly not good hearted. Such groups always seek outgroups, and will manufacture them if everyone becomes the same.
In complicated societies there are overlapping spheres of identity in social life. Disjointed spheres may mean that it is harder to distinguish yourself from others, so you become more complacent about difference. However, the more your identity is defined by categories which smoothly overlap or concatenate, then the more you might perceive the difference between your group and out groups, and the more that outgroups can become sites for projection of fantasies. So groups can drive each other apart. But sometimes you get a dynamic whereby one group wants to be more like the other, and the other repels them – so the groups move further towards a similar extreme. In the US Democrats become more Republican, and Republicans move further to the ‘right’ to distinguish themselves.
5) The more the ideas expressed by a person praise the shared information and biases of the group, the more persuasive they are, and the higher status they gain. The more the ideas expressed by a person appear to resemble the ideas expressed by the outgroup, the less persuasive they are and the more marginal and threatened their status – they may even risk expulsion.
6) Ideas become relevant in different circumstances and different conflicts with the out groups…
Hence group members do not have to worry, or even notice, if those ideas are compatible with each other or not. There is no necessity for ideas to be coherent because they primarily serve as markers of self-identity, loyalty and differentiation from the outgroups in different circumstances.