PKT message, Re. Causation In Theory

Jonathan:

I have inserted some comments below:

----- Original Message -----

To: Harry Veeder <veed0001@xxxxxxxxxxxxxxxx>

Cc: POST KEYNESIAN THOUGHT <pkt@xxxxxxxxxxxxxxxx>

Sent: Friday, May 26, 2000 5:58 AM

Subject: Re: causation in theory

At the risk of getting too philosophical, here are some comments on the recent discussion of causation:

Newton did indeed deny that his laws identified causes, in keeping with his slogan "Hypotheses non fingo" (pardon any misspelling). But he didn't do this because he thought his laws were merely predictive in a statistical sense.

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Comment:

Or, as I would put it, Newton understood that his "laws" are (a) not causal, and (b) predictive.

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He thought that they could be exploited to manipulate events, carrying out the project set by Bacon to first understand how we are subject to nature in order to dominate it. In this sense, perhaps the most important sense, his laws can be called causal laws.

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Comment:

This is so with respect to what used to be called "art" as distinct from "science"; it was with respect to the latter alone that Keynes spoke of "The Theory of Economics" as "a method rather than a doctrine, an apparatus of the mind, a technique of thinking, which helps its possessor to draw correct conclusions."

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I think (but am not certain) that like a large number of early modern natural philosophers Newton required of causation that one assume a necessary connection between cause and effect, and he denied that we can have any such knowledge. Only God could. The reasons are complicated, but many philosophers of the age
believed it, including anti-empiricists like Malebranche, long before Hume arrived and pretty much eliminated even the theistic solace. This denial of causal knowledge (at least as it appears in the Occasionalists and Hume) is just a species of philosophical skepticism. But whatever we were sensibly talking about when we spoke of causes, it wasn't incorrigible knowledge of future events or of the necessary results of states of affairs.

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Comment:

In his comments on Newton which I cited earlier, Hume spoke of "Nature's ... ultimate secrets" being shrouded in "that obscurity in which they ever did and ever will remain."

As for Nature's "secrets" as manifested in space and time, I construe Hume's conclusion as fully consistent with the view-point which Einstein expressed as follows:

"The supreme task of the physicist is to arrive at those universal laws from which the cosmos can be built by pure deduction. There is no logical path to these laws; only intuition, resting on sympathetic understanding understanding of experience, can reach them."

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I think Harry had the right take on it: even if we want to be 'hard-headed' types, we can treat causal assertions in a quasi-Popperian spirit: they are falsifiable hypotheses which allow us to make strong predictions (stronger and different from statistical relationships which no longer apply when structural conditions change...and what
are structural conditions but causal conditions!). If the predictions are right, great; if they're wrong, back to the
drawing board. But I don't think this attitude has a clear application when the causal relations among the
phenomena change (that is, when everything shifts and nothing like the laws of physics are present). All
regularities of action, of course, have the systematic problem that people react to predictions in order to realize or prevent them. I think scientism really must be eradicated at the roots in economics, but that's another story.

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Comment:

If we hold the "supreme task of the physicist" to be that of which Einstein spoke, then the only test of some future Unified Theory Of Everything is the non-Popperian test of logical coherence.

This is also true of "The Theory Of Economics" as defined by Keynes - "an apparatus of the mind" that lacks logical coherence cannot in principle comprise any part of economic "science".

In a memorial article on him, Samuelson expressed surprise that Schumpeter had regarded economic science as "a branch of logic" - so did John Stuart Mill, who ascribed the like view to "all" his predecessors of first rank.

Friedman, in his essay on 'The Methodology of Positive Economics', took a somewhat different tack:

"Logical completeness and consistency are relevant but play a subsidiary role; their function is to assure that the hypothesis says what it is intended to say and does so alike for all users - they play the same role here as checks for arithmetical accuracy do in statistical computations."

Considering also what his critics used to call Friedman's "black-box" approach to economic theorizing, it is clear that the role which he accords "logical completeness and consistency" therein differs from that of Mill, Schumpeter, and Keynes.

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Anyway, my first point was that by denying causation and insisting that the laws were confirmed by their predictive merits, Newton and others were not asserting that the laws were no more than statistical correlations. They were assumed to be rigid regularities (i.e., LAWS) which could be used to change any fluid regularities (i.e., mere correlations) with the proper tools, but which could not themselves be changed.

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Comment:

I have no reason to believe that Newton would have taken exception to the following statement by Christian Huygens in Preface to the latter's 'Treatise on Light':

"There will be seen in it demonstrations of those kinds which do not produce as great a certitude as those of geometry, and which even differ much therefrom, since, whereas the geometers prove their propositions by fixed and incontestable principles, here the principles are verified by the conclusions to be drawn from them; the nature of these things not allowing of this being done otherwise. It is always possible to attain thereby to a degree of probability which very often is scarcely less than complete proof. To wit, when things which have been demonstrated by the principles that have been assumed correspond perfectly to the phenomena which experiment has brought under observation; especially when there are a great number of them, and further, principally, when one can imagine and foresee new phenomena which ought to follow from the hypotheses which one employs, and when one finds that therein the fact corresponds to out prevision."

In turn, this epistemological maxim (a) is perfectly suited for work on "the supreme task of the physicist," as defined by Einstein, and (b) accords with what I construe as Hume's distinction between that which lies within and without the boundaries of the scientific quest.

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There has been a lot of work recently on the relationship between causation and the ideas of manipulation and
interference. Judea Pearl's 'Causality' is very interesting. An excellent discussion appears in 'On the Reliability of Economic Models' edited by Daniel Little (see the essays by Woodward, Cartwright, and Hoover). Huw Price also has written on causal asymmetries and the symmetrical laws of physics, and on the notion of agency as the fundamental causal notion (I think the book is called Time's Arrow).

I hope this hasn't been too much.

Jonathan Halvorson

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Ditto!

Gunnar Tomasson