"I'd like to see why the field is the best possible explanation for the way people behave in groups, and therefore why it is necessary to postulate the existence of such a field in order to explain same. In a nutshell, what does having a field do for us that conventional psychological explanations about group dynamics do not?"
Quantum theory is rigorous and "objective" in a way that conventional psychological observation and explanation are not. Freud, for example, arguably built quite a lot of subjective musing into his theories. Modern psychology does not seem to have paid much attention to the fact that human subjects, and all other living beings, participate in and are "constituted" by a variety of universal fields (e.g., acoustic, gravitational, EM, quantum). The macroworld we see in all its seemingly infinite variety is, at its most basic level, constituted of particle exchanges occurring in their relevant field(s). These quantum events are characterized by the quality of non-locality: spontaneous quantum superposition and entanglement, "in no time." A quantum event that is observed happening "here" right now, though we may perceive it to be "local," actually may have global spread -- to the furthest reaches of the universe, in fact.
Here's a great article to read, if you are interested in the technical details of Attila Grandpierre's consciousness theory:
http://www.konkoly.hu/staff/grandpierre/wf97.html An excerpt:
"Psychological researches teach that consciousness is vital when it is filled with emotional drives. Positive emotions enhance the dominating role of the neocortex in the brain activity ( Völgyesi, 1962). Our research (see Endre K. Grandpierre, this and a later volume) shows, that the basic and first step of any conscious activity is an interaction. If consciousness works through EM fields, its activity in every step involves changes in its EM field and the interaction of its EM field with another EM field - outer or of an inner subsystem. It means that EM induction results, which generates naturally a higher level of electromagnetic activity besides the overlapping and superposition of the two interactive EM fields. Consequently, the interactive EM fields when they are active, generate a subsidiary EM field, a ‘daughter’ field. This induction effect is suggested to be the physical basis of the ‘group effect’, the enhancement of the basic activity level when entering into interaction with another human being, consciously or without being aware of it. Therefore, the consciousness can not be regarded developed and healthy, if its ‘exploration drives’ and ‘general activity drives’, emotional motivations and desires are passive, and are hindered by the aware consciousness. Consciousness develops through the phenomenon of ‘emotional infection’, widespread among children, and also present in rituals and when masses of people form a community. In new-born children, the movements originate from spontaneous emotional reactions, their sources are within the emotional system (Wallon, H., 1946). '... The propensity to interact originates from the nature of emotions, of their mutuality (Endre K. Grandpierre, this volume) and field-nature, which is the basis of the well-known phenomenon of ‘transference’, the easy transfer of emotions in the trance-state from one person to another. This is the basis of the transference of emotions, its epidemic character, as well as the wide-range phenomena of mass psychosis and collective impulses, when the individual consciousnesses merge into one single common consciousness (Wallon, ibid.). ...
Emile Durkheim (1899) showed the existence of collective psychical fields. He showed that the reality of the collective psychical fields is of the same degree as that of the physical fields, since it is measurable (through social indexes), and its relations and consequences show the same rate of stability. The collective psychical field generates a remarkably stable rate of suicides in a given nation. Individuals forming the society change from year to year, but the rate of suicides remains stable. This rate is different in different nations, and seems to be determined by moral factors. Moral life is per se a collective phenomenon, and the collective psychical field is an expression of the background moral fields of individuals. Our moral convictions are a certain kind of concerted brain activities, formed from our common characteristics. This is expressed also in the changes of the social indexes of e.g. suicide. Durkheim observed, that the activity of the society follows a seasonal rhythm, its intensity grows from January to July, and then decreases. Durkheim pointed out, that the suicidal index of the people living in marriage shows the same ratio to that of people of the same social class being widows, indifferently from the selected class. The simple reason for this is that the judgement of the society is of a general character, independent of the actual group of the society, although the social conditions of life sensitively change from group to group, therefore becoming widow would show a larger relative loss in the lower classes. Moral judgements are closely related to emotions, therefore we are led to the inference that common field of consciousness consists of emotions. "
Of course, Durkheim was working in pre-QM science. When he spoke of "fields,"he was speaking of "social fields." He had to work with "macroworld" assumptions based on classical physics and statistical and observational techniques in order to derive his indices. Such were found to be remarkably stable over time. I imagine that using the techniques of quantum science may reveal the structures/processes that produce this stability, assuming proper experiments can be constructed.
The point is, consciousness fields may be more than social fields:
"As early as 1892 Maxwell recognised that the EM energy is present in the circuit and the EM field simultaneously. He understood that the current is able to perform electrolysis locally, to develop Joule-heat locally, and the ability to do work locally involves local energy. At the same time, the energy is also present in the form of field energy. Maxwell suggested that a part of the EM energy is present locally and the remaining part is present globally (1892, Vol. II, p. 212). Nevertheless, the calculations lead to equal amounts of energy, and when one form of EM energy changes, the other form changes simultaneously. Feynman, the founder of quantum electrodynamics, expressed a view that the energy is present in the field globally- but he is silent about the local EM energy (Feynman et al., 1963). The presence of this primary EM field offers for the first time the actual, immediate ‘action in distance’, which has a significance of overall importance, in the understanding the nature of the field of consciousness, as well. It is interesting, that Maxwell himself, in the last chapter “Theories of action at a distance” of his book recognized the instantaneous character of some EM effects: “An electric particle sends forth a potential, the value of which ee’/r, depends not only on e, the emitting particle, but on e’, the receiving particle, and on distance r between the particles at the instant of emission” (Maxwell, 1892). This primary EM field may serve as a physical basis for the ‘spontaneous targeting’ introduced above, the ‘spontaneous collapse’ of the waves to the site of interaction or observation, thus solving the central measurement problem of the present day quantum theory, and the ‘primary perception’, which is a yet unnoticed effect, but discovered independently and simultaneously by the present author and Endre K. Grandpierre (this volume). This primary EM field may help in maintaining the ‘global organization’ and ‘informational transparency’ described above. "