Template:M intro design Nomological machine: Difference between revisions

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 “It is a fixed (enough) arrangement of components, or factors, with stable (enough) capacities that in the right sort of stable (enough) environment will, with repeated operation, give rise to the kind of regular behavior that we represent in our scientific laws” <ref>{{author|Nancy Cartwright}}. {{br|The Dappled World – A Study of the Boundaries of Science}}. (Cambridge University Press, 1999)</ref>}}
-As a piece of marketing, this is a ''terrible'', obscurant — if technically accurate — label.<ref>Like academics, lawyers learn to use the arcane vocabulary of the [[power structure]] while on the lower rungs of the profession: it is a credentialing strategy and part of the tribal identification ritual. By the time they get high enough on the latter to influence how their underlings write they have often lost the ability to write clearly and simply. Cartwright is a brilliant thinker, but her writing is dense and hyper-academic.</ref> A better name would be “regularity machine”: a device designed to generate ''regularities'': to winnow out any chattering and crosstalk and produce the pure, untrammeled outcomes your theory predicts.
+As a piece of marketing, this is a ''terrible'', obscurant — if technically accurate — label.<ref>Like academics, lawyers learn to use the arcane vocabulary of the [[power structure]] while on the bottom rungs of the profession as a means of climbing up it: it is a credentialing strategy and part of the tribal identification ritual. By the time they get high enough to influence how the upcoming generations write, they have often forgotten how to write clearly and simply themselves. Cartwright is a brilliant thinker, but her writing is dense and academic.</ref> A better name would be “regularity machine” or even just a ''model'': a device designed to generate ''regularities'' predicted by the theory by filtering out the inconvenient chattering, debris and crosstalk we get in real life, to extract the pure, untrammeled outcomes your theory predicts.
 So, for example, take Newton’s second law of motion, ''F=ma''. The ''force'' (F) acting on an object is equal to its ''mass'' (m)  times its ''[[acceleration]]'' (a).
-This is an immutable law of physics.<ref>For all non-relativistic, non-quantum scales.</ref> But the conditions in which it holds — zero friction, perfect elasticity, a non-inertial frame of reference — never prevail in “the field”. In life, there is always friction, energy loss through heat, wind, and impurity. The neat formula, with all these unrealistic conditions, is a ''nomological machine''. If the universe does not seem to obey the law, we can blame shortcomings in observed criteria. The nomological machine is not properly represented.
+If we apply a force of one Newton to a one kilogramme ball it will travel at 10 metres per second.
-A rolling ball with no force upon it will eventually stop. This is, so the theory goes, only because of the corruption of reality. So too, a [[crisp packet|crisp packet blowing this way and that across St. Mark’s square]]. Once you have discounted all the contaminating effects of the real world; the friction, convection, dust, drafts and so on, it still does, we ''assume'' obey Newton’s laws — but good luck proving that out. For every crisp packet, for every rolling ball, ''for every mass that ever accelerates in our imperfect human world'', we give Newton the benefit of a large and practically untestable doubt.
+This is an immutable law of physics.<ref>For all non-relativistic, non-quantum scales.</ref> But the conditions in which it holds — zero friction, perfect elasticity, a non-inertial frame of reference — never prevail in “the field”. In life, there is always friction, energy loss through heat, wind, and impurity. We can never  be sure, either of our measurements — was it exactly a newton? — nor whether the force was perfectly flush, whether our speedometer was correctly calibrated. So we expect the prediction to be near enough without being accurate to the micrometer. The neat formula, with all these unrealistic conditions, is a ''nomological machine''. If the universe does not seem to obey the law, we can blame shortcomings in observed criteria. The nomological machine is not properly represented.
-But are we justified in extrapolating laws that hold for nomological machines to the real world? Do these imaginary regularity generators ''really'' tell us how wind-blown crisp packets, or any of the other myriad quotidian physical effects we see and take for granted every day, behave? Is this a ''conjuring'' trick?
+Also, near enough is good enough — we don't need micrometric perfection. It is too hard to calculate and we don't have the data in any case.
+It is said that, when calculating trajectories during the Apollo programme, NASA scientists used Newtonian mechanics rather than Einstein’s more accurate calculations, because the relativistic maths was too hard to do on a slide rule.
+A rolling ball with no force upon it will eventually stop. This is, so the theory goes, only because of the corruptions of reality. So too, a [[crisp packet|crisp packet blowing this way and that across St. Mark’s square]]. Once you have discounted all the contaminating effects of the real world; the friction, convection, dust, drafts and so on, it still does, we ''assume'' obey scientific canon — but good luck proving it. For every lunar module, crisp packet, or every rolling ball, ''for every mass that ever accelerates in our imperfect human world'', we give our models the benefit of a large and practically untestable doubt.
+But are we justified in extrapolating laws that hold for nomological machines to the real world? Do these imaginary regularity generators ''really'' tell us how wind-blown crisp packets, or any of the other myriad quotidian physical effects we see and take for granted every day, behave? Is this a ''conjuring'' trick? To find out, read Cartwright’s book. It is called, {{br|How the Laws of Physics Lie}}.
+Now: there are theoretical models of life — nomological machines — and life-based models of theory — for a laugh, let’s call these ''analogical machines'' — in which we use real life artefacts to generate a theoretical result — coins and dice to generate randomised outcomes — and it is important not t to confuse them.
+==== Tumbling dice as analogical machines ====
+There are two kinds of dice. ''Hypothetical'' dice, which are used to illustrate probabilities, ergodicity and the like— “imagine you rolled a dice ten million times” kind of thing — and ''actual'' dice, which we use to force probabilistic outcomes we need for other purposes. Dice we roll when playing monopoly, coins we flip to decide who kicks off, and so on. The former are nomological machines. They are designed to explore and articulate the theoretical implications of mathematical theory. The latter are the opposite. They are actual machines which we design to behave as closely as possible to hypothetical dice. Fortunately the parameters of the normal logical machine called the dice are very simple: they need only six equal, evenly waited sides and to land on a flat constrained surface. Even cheap, toy dice can fulfill these criteria fairly faithfully.
-==== Tumbling dice as nomological machines ====
 When we calculate probabilities — when we roll dice — we are in situations of ''known risk''. Even though their trajectories are chaotic; even though no two rolls are identical, all this intractable uncertainty is wiped out when the dice come to rest. At that stage, we know the range of possible outcomes and their calculated probabilities. On a flat, hard surface, one side must come to rest face-up. There are six equal sides. We deduce each side has a ⅙ probability.