The rapid adoption theory is perhaps the weakest of the three for it relies heavily on presumed information about the nature of the hoplon shield and the military necessity of hoplite equipment. This model was developed by historians Paul Cartledge and Victor Hanson.
This model proposes that one polis or military force developed the phalanx individually. This phalanx was so effective that others had to adapt the formation as well as the equipment or else they would be easily defeated. The primary belief is that the equipment came as a result of the phalanx over the period of 725 – 675 BC.
One of the primary arguments Hanson proposes is that the double-grip of the hoplon shield, as well as it’s concavity, was a result of the phalanx. He says that the concavity was formed so that the men who weren’t in the front ranks of the phalanx weren’t fighting, they could rest it on their shoulder. This disregards the belief that the shield’s size was to protect the entire formation, not just the individual soldier (Hanson).Another argument of the rapid adoption theory is that the butt-spike on the eight foot long spear was an amor piercing tip designed to execute fallen enemy combatants as the phalanx marches over them. This proposal may be true, but there is no distinct ancient evidence for it besides its armor-piercing shape.
The main concern the academic community has with this model is that it’s very binary. There’s no middle ground, either there was the phalanx as we know it, or there was nothing at all. It also disregards the evidence we have of a possible transitional form of the phalanx, which will be discussed in the next section.