As it happens, an essay by Christian Arnsperger & Yanis Varoufakis may provide us with the answer. In this essay, Arnsperger and Varoufakis attempt to define neoclassical methodology, hoping to nullify its lizard-like ability to dispose of certain parts in order to evade criticism. Personally, I think they hit the nail on the head.
They provide three axioms which define neoclassical methodology:
(1) Methodological individualism – the economy is modeled on the basis of the behaviour of individual agents.
(2) Methodological instrumentalism – individuals act in accordance with certain preferences rankings, to attain some end goal that they deem desirable.
(3) Methodological equilibration – given the above two, macroeconomics asks what will happen if we assume equilibrium. Note that this doesn’t necessarily posit that the system will end up in equilibrium (although that is often the case), but rather seeks to find out what will happen if we use equilibrium as an epistemological starting point.
I will not criticise the axioms here, but suffice to say that this gets to the crux of what the arguments have been about. This methodological core underlies everything from demand-supply to game theory to DSGE.
Much like the assumption of circular orbit, the methodological core of neoclassicism is at all times protected as it develops. Most neoclassical economists don’t think twice about the axioms, and this helps them deny that they are, in fact, ‘neoclassical’, seeing it only as a buzz word used by their enemies.
In fact, neoclassical economics has a habit of preserving not only these three axioms, but also many other assumptions it introduces. For example, take the case of Krugman and Eggertson versus Keen. Keen models the banks as explicit agents and creators of purchasing power, whilst Krugman and Eggertson preserve the ‘banks as intermediaries between savers and borrowers’ line, abstracting them out the economy, and ad-hocing a role for private debt.
You can also see these axioms in criticisms of Keen’s models. Krugman says that there is ‘a lot of implicit theorising’ going on in Keen’s paper. Perhaps this is true and maybe Keen needs to clarify his epistemology, but what Krugman really means - unknowingly, perhaps – is that Keen doesn’t start from the three axioms: he isn’t looking at individual behaviour, instead at the flow of money between agents; nobody is acting in accordance with attaining certain preferences; equilibrium is not used as a starting point. From my experience, I strongly suspect that most mainstream economists feel a similar skepticism when reading Keen’s paper.
I believe that in order for the debate to move forward, these 3 axioms – and others that are protected by the ad hoc style of DSGE – must be focused on and criticised. Otherwise critics will never land a convincing blow, and will be forever accused of straw manning.
* As a note, Austrians, this is why I link you with neoclassicism. The first two certainly define all of Austrian economics, and, at least in the case of Hayek, you also use equilibrium as an epistemological starting point.