The non-existence of economic laws

from Lars Syll

In mainstream economics, there’s — still — a lot of talk about ‘economic laws.’ The crux of these laws — and regularities — that allegedly exist in economics, is that they only hold ceteris paribus. That fundamentally means that these laws/regularities only hold when the right conditions are at hand for giving rise to them. Unfortunately, from an empirical point of view, those conditions are only at hand in artificially closed nomological models purposely designed to give rise to the kind of regular associations that economists want to explain. But, really, since these laws/regularities do not exist outside these ‘socio-economic machines,’ what’s the point in constructing thought experimental models showing these non-existent laws/regularities? When the almost endless list of narrow and specific assumptions necessary to allow the ‘rigorous’ deductions are known to be at odds with reality, what good do these models do?

Deducing laws in theoretical models is of no avail if you cannot show that the models — and the assumptions they build on — are realistic representations of what goes on in real life.

Conclusion? Instead of restricting our methodological endeavours to building ever more rigorous and precise deducible models, we ought to spend much more time improving our methods for choosing models!

Cutting-edge macroeconomics …

from Lars Syll

No sooner had I finished my comment on the irrelevancy of economics but I had confirmation — albeit unwittingly — in this morning’s Financial Times.  There on the editorial page was a short column by Soumaya Keynes talking about the rise of Hank.

For those of you not on the cutting edge, “Hank” stands for Heterogeneous Agent New Keynesian, as in a complicated model of the economy.

Hank is a whole new way of looking at model economies, with the really big breakthrough being that it includes — roll the drums please — more than one household.

Yes, economists are moving at a rapid pace.  Their research has shown that the economy includes more than one household.

Gasp.

If you are a sociologist or anthropologist you are forgiven at this point for laughing out loud.

Reflect, if you will, on the enormous hubris expressed by Steve Levitt when he criticized economics for becoming too inwardly focused and potentially irrelevant.  His condemnation was absolute.  He said that economics risked falling into the kind of disrepair that, in his mind at least, make sociology and anthropology laughingstocks.  Now, I don’t know sociology or anthropology all that well, but I imagine they don’t base a substantial amount of their theoretical effort on the notion that America has only one household.  Even if that household is “representative”.

Representative of what?  Some Chicago-trained logician masquerading as an economist?

Peter Radford

Yes indeed, ‘Hank’ and similar modelling approaches are nothing but convenient untruths — and still economists rely on them to derive policy implications!

Chicago economics — nothing but pseudo-scientific cheating

from Lars Syll

Unlike anthropologists … economists simply invent the primitive societies we study, a practice which frees us from limiting ourselves to societies which can be physically visited as sparing us the discomforts of long stays among savages. This method of society-invention is the source of the utopian character of economics; and of the mix of distrust and envy with which we are viewed by our fellow social scientists. The point of studying wholly fictional, rather than actual societies, is that it is relatively inexpensive to subject them to external forces of various types and observe the way they react. If, subjected to forces similar to those acting on actual societies, the artificial society reacts in a similar way, we gain confidence that there are useable connections between the invented society and the one we really care about.

Robert Lucas

Neither yours truly, nor anthropologists, will recognise anything in Lucas’ description of economic theory even remotely reminiscent of practices actually used in real sciences, this quote still gives a very good picture of the methodology used by Lucas and other prominent Chicago economists.

What’s the use of economics?

from Lars Syll

The simple question that was raised during a recent conference … was to what extent has — or should — the teaching of economics be modified … The simple answer is that the economics profession is unlikely to change. Why would economists be willing to give up much of their human capital, painstakingly nurtured for over two centuries? For macroeconomists in particular, the reaction has been to suggest that modifications of existing models to take account of ‘frictions’ or ‘imperfections’ will be enough to account for the current evolution of the world economy. The idea is that once students have understood the basics, they can be introduced to these modifications …

I would go further; rather than making steady progress towards explaining economic phenomena professional economists have been locked into a narrow vision of the economy. We constantly make more and more sophisticated models within that vision until, as Bob Solow put it, “the uninitiated peasant is left wondering what planet he or she is on” …

Every student in economics is faced with the model of the isolated optimising individual who makes his choices within the constraints imposed by the market. Somehow, the axioms of rationality imposed on this individual are not very convincing, particularly to first-time students. But the student is told that the aim of the exercise is to show that there is an equilibrium, there can be prices that will clear all markets simultaneously. And, furthermore, the student is taught that such an equilibrium has desirable welfare properties. Importantly, the student is told that since the 1970s it has been known that whilst such a system of equilibrium prices may exist, we cannot show that the economy would ever reach an equilibrium nor that such an equilibrium is unique.

The student then moves on to macroeconomics and is told that the aggregate economy or market behaves just like the average individual she has just studied. She is not told that these general models in fact poorly reflect reality. For the macroeconomist, this is a boon since he can now analyse the aggregate allocations in an economy as though they were the result of the rational choices made by one individual. The student may find this even more difficult to swallow when she is aware that peoples’ preferences, choices and forecasts are often influenced by those of the other participants in the economy. Students take a long time to accept the idea that the economy’s choices can be assimilated to those of one individual.

Alan Kirman What’s the use of economics?

An economic theory that does not go beyond proving theorems and conditional ‘if-then’ statements — and does not make assertions and put forward hypotheses about real-world individuals and institutions — is of little consequence for anyone wanting to use theories to better understand, explain or predict real-world phenomena.

I heard there’s some good shit on TV tonight …

from Lars Syll

Time is a scarce resource on television. However, if one still — as is so often the case nowadays — uses precious airtime for trivial matters and meaningless ‘entertainment,’ there must be a reason. Television is — still — for a large part of the population one of the primary sources of information and worldview. Thus, filling program schedules with trivialities becomes an effective means to — instead of functioning as an instrument for shaping opinions and fostering reflection — push aside important information that citizens would need to exercise and develop their democratic capabilities.

Television, through its focus on personalities and banalization of various ‘affairs,’ creates a poor environment for real knowledge dissemination. Instead of serious opinion formation, we get demagogic programs where quick-witted, shallow individuals with limited knowledge expound on everything and nothing, but especially on topics they know nothing about.

Utility theory — explaining everything and nothing

from Lars Syll

Despite the rise of behavioral economics, many economists still believe that utility maximization is a good explanation of human behavior. Although evidence from experimental economics and elsewhere has rolled back the assumption that human agents are entirely self-interested, and shown that altruism and cooperation are important, a prominent response has been to modify individual preference functions so that they are “other-regarding”. But even with these modified preference functions, individuals are still maximizing their own utility.

Defenders of utility maximization rightly reject critical claims that specific behavioral outcomes undermine this assumption. They do not. But this is a sign of weakness rather than strength. The problem is that utility maximization is unfalsifiable as an explanation of behavior. As I show more fully in my 2013 book entitled From Pleasure Machines to Moral Communities, utility maximization can fit any real-world evidence, including behavior that appears to suggest preference inconsistency.

But note that utility maximization is not a tautology. Tautologies are true by assumption or definition. Utility maximization is not a tautology because it is potentially false. But empirically it is unfalsifiable.

Where does that leave us? Utility maximization can be useful as a heuristic modelling device. But strictly it does not explain any behavior. It does not identify specific causes. It cannot explain any particular behavior because it is consistent with any observable behavior. Its apparent universal power signals weakness, not strength.

Geoff Hodgson

Interesting post from one of yours truly’s favourite economists. 

The problem with economics — too much maths, too little history

from Lars Syll

Mainstream economists have always wanted to use their hammer, and so have decided to pretend that the world looks like a nail. Pretending that uncertainty can be reduced to risk and that all activities, relations, processes, and events can be adequately converted to pure numbers, have only contributed to making economics irrelevant and powerless when confronting real-world financial crises and economic havoc.

How do we put an end to this intellectual cataclysm? How do we re-establish credence and trust in economics as a science? Five changes are absolutely decisive.

(1) Stop pretending that we have exact and rigorous answers to everything. Because we don’t. We build models and theories and tell people that we can calculate and foresee the future. But we do this based on mathematical and statistical assumptions that often have little or nothing to do with reality. By pretending that there is no really important difference between model and reality we lull people into thinking that we have things under control. We haven’t! This false feeling of security was one of the factors that contributed to the financial crisis of 2008.

(2) Stop the childish and exaggerated belief in mathematics giving answers to important economic questions. Mathematics gives exact answers to exact questions. But the relevant and interesting questions we face in the economic realm are rarely of that kind.

Game theory — a waste of time on a staggering scale

from Lars Syll

We certainly agree that regularities or models that explain or that give heuristic value over many different cases are highly desirable. But ones that do neither are not — especially if they use up huge resources along the way. When looking at the details, the Prisoner’s Dilemma’s explanatory record so far is poor and its heuristic record mixed at best. The only way to get a reliable sense of what theoretical input would actually be useful is via detailed empirical investigations. What useful contribution — whether explanatory, heuristic or none at all — the Prisoner’s Dilemma makes to such investigations cannot be known until they are tried. Therefore resources would be better directed towards that rather than towards yet more theoretical development or laboratory experiments.

R. Northcott & A. Alexandrova

Game theory is, like mainstream economics in general, model-oriented. There are many reasons for this – the history of the discipline, having ideals coming from the natural sciences (especially physics), the search for universality (explaining as much as possible with as little as possible), rigour, precision, etc. Most mainstream economists and game theorists want to explain social phenomena, structures and patterns, based on the assumption that the agents are acting in an optimizing (rational) way to satisfy given, stable and well-defined goals.

Why economics is an impossible science

from Lars Syll

In a word, Economics is an Impossible Science because by its own definition the determining conditions of the economy are not economic: they are “exogenous.” Supposedly a science of things, it is by definition without substance, being rather a mode of behavior: the application of scarce means to alternative ends so as to achieve the greatest possible satisfaction—neither means, ends, nor satisfaction substantially specified. Exogenous, however, is the culture, all those meanings, values, institutions, and structures, from gender roles, race relations, food preferences, and ethnicities, to technical inventions, legal regulations, political parties, etc., etc. The effect is a never-ending series of new theoretical breakthroughs, each an Economics du jour worthy of a Nobel prize, consisting of the discovery that some relevant little bit of the culture has something to do with it. Only to be soon superseded and forgotten since the continuous development and transformation of the culture, hence of the economy, leaves the Science in its wake. An impossible Science, by its own premises.

Marshall Sahlins

The increasing mathematization of economics has

Mainstream economics — an explanatory disaster

from Lars Syll

To achieve explanatory success, a theory should, minimally, satisfy two criteria: it should have determinate implications for behavior, and the implied behavior should be what we actually observe. These are necessary conditions, not sufficient ones. Rational-choice theory often fails on both counts. The theory may be indeterminate, and people may be irrational. In what was perhaps the first sustained criticism of the theory, Keynes emphasized indeterminacy, notably because of the pervasive presence of uncertainty …

Disregarding some more technical sources of indeterminacy, the most basic one is embarrassingly simple: how can one impute to the social agents the capacity to make the calculations that occupy many pages of mathematical appendixes in the leading journals of economics and political science and that can be acquired only through years of professional training? …

I believe that much work in economics and political science that is inspired by rational-choice theory is devoid of any explanatory, aesthetic or mathematical interest, which means that it has no value at all. I cannot make a quantitative assessment of the proportion of work in leading journals that fall in this category, but I am confident that it represents waste on a staggering scale.

Jon Elster

Most mainstream economists want to explain social phenomena, structures and patterns, based on the assumption that the agents are acting in an optimizing (rational) way to satisfy given, stable and well-defined goals.

The procedure is analytical. The whole is broken down into its constituent parts to be able to explain (reduce) the aggregate (macro) as the result of the interaction of its parts (micro). Building their economic models, modern mainstream economists ground their models on a set of core assumptions describing the agents as ‘rational’ actors and a set of auxiliary assumptions. Together these assumptions make up the base model of all mainstream economic models. Based on these two sets of assumptions, they try to explain and predict both individual and social phenomena.

Econometric modeling and inference

from Lars Syll

The impossibility of proper specification is true generally in regression analyses across the social sciences, whether we are looking at the factors affecting occupational status, voting behavior, etc. The problem is that as implied by the three conditions for regression analyses to yield accurate, unbiased estimates, you need to investigate a phenomenon that has underlying mathematical regularities – and, moreover, you need to know what they are. Neither seems true … Even if there was some constancy, the processes are so complex that we have no idea of what the function looks like.

Researchers recognize that they do not know the true function and seem to treat, usually implicitly, their results as a good-enough approximation. But there is no basis for the belief that the results of what is run in practice is anything close to the underlying phenomenon, even if there is an underlying phenomenon. This just seems to be wishful thinking. Most regression analysis research doesn’t even pay lip service to theoretical regularities. But you can’t just regress anything you want and expect the results to approximate reality. And even when researchers take somewhat seriously the need to have an underlying theoretical framework … they are so far from the conditions necessary for proper specification that one can have no confidence in the validity of the results.

Steven J. Klees

Most work in econometrics and regression analysis is done on the assumption that the researcher has a theoretical model that is ‘true.’ Based on this belief of having a correct specification for an econometric model or running a regression, one proceeds as if the only problem remaining to solve has to do with measurement and observation.

The problem is that there is little to support the perfect specification assumption.

The loss of confidence in economists’ analyses

from Lars Syll

Ainsi, la crise de 2008 a créé la surprise dans les rangs des économistes influents, qui croyaient voir le monde entrer au XXIe siècle dans le temps de « la grande modération » – c’est-à-dire la prévention des mouvements économiques erratiques grâce au pilotage « scientifique » des politiques monétaires …

Cet épisode a sans conteste révélé une défaillance sévère du savoir économique …

Pourquoi cette perte de confiance envers les analyses des économistes ? Nous vivons aujourd’hui une « seconde mondialisation », dont la complexité spécifique et croissante ne se résume plus à la mécanique des marchés. Un vaste chantier de retour sur le savoir existant s’est ouvert, dont voici, sans prétention à l’exhaustivité, quelques têtes de chapitre : la mécanique de l’innovation, la coordination des anticipations dans un monde élargi et ouvert, la distribution des revenus et les inégalités au sein des nations ou entre nations.

Roger Guesnerie

Contrary to Guesnerie, I think the ‘confidence’ mainstream economists have in their own theories and models, basically is a question of methodology. When applying deductivist thinking to economics, economists usually set up ‘as if’ models based on a set of tight axiomatic assumptions from which consistent and precise inferences are made. The beauty of this procedure is of course that if the axiomatic premises are true, the conclusions necessarily follow. The snag is

‘New Keynesianism’ — more useless than ever

from Lars Syll

“the heart of darkness in ‘New Keynesian’ macroeconomics”

Macroeconomic models may be an informative tool for research. But if practitioners of ‘New Keynesian’ macroeconomics do not investigate and make an effort to provide a justification for the credibility of the assumptions on which they erect their building, it will not fulfil its tasks. There is a gap between its aspirations and its accomplishments, and without more supportive evidence to substantiate its claims, critics will continue to consider its ultimate argument as a mixture of rather unhelpful metaphors and metaphysics. Maintaining that economics is a science in the ‘true knowledge’ business, yours truly remains a sceptic of the pretences and aspirations of ‘New Keynesian’ macroeconomics. So far, I cannot really see that it has yielded very much in terms of realistic and relevant economic knowledge.

Keynes basically argued that it was inadmissible to project history on the future. Consequently, an economic policy cannot presuppose that what has worked before, will continue to do so in the future. That macroeconomic models could get hold of correlations between different ‘variables’ was not enough. If they could not get at the causal structure that generated the data, they were not really ‘identified.’ Dynamic stochastic general equilibrium (DSGE) macroeconomists — including ‘New Keynesians’ — have drawn the conclusion that the problem with unstable relations is to construct models with clear microfoundations where forward-looking optimizing individuals and robust, deep, behavioural parameters are seen to be stable even to changes in economic policies. As yours truly has argued in a couple of posts (e. g. here and here), this, however, is a dead end.

Here we are getting close to the heart of darkness in ‘New Keynesian’ macroeconomics.

Scientific fraud

from Lars Syll

In 2022, the U.S. National Institutes of Health (NIH) placed a large bet on an experimental drug developed to limit brain damage after strokes …

The gamble seemed warranted. Lab studies, most by a longtime grantee, prominent University of Southern California (USC) neuroscientist Berislav Zlokovic, had generated promising data. A small safety study of the drug, sponsored by a company Zlokovic co-founded called ZZ Biotech, was also encouraging.

Because of its potential to address an unmet medical need, the U.S. Food and Drug Administration (FDA) gave the compound “fast track” status, with the prospect of “accelerated approval and priority review.” ZZ Biotech says the new trial should start within a few months …

But a 113-page dossier obtained by Science from a small group of whistleblowers paints a less encouraging picture …

The dossier highlights evidence that dozens of papers from Zlokovic’s lab—including many supporting the idea that the compound was ready for human testing—contain seemingly doctored data that suggest scientific misconduct …

Speaking to Science anonymously, four former members of Zlokovic’s lab say the anomalies the whistleblowers found are no accident. They describe a culture of intimidation, in which he regularly pushed them and others in the lab to adjust data. Two of them said he sometimes had people change lab notebooks after experiments were completed to ensure they only contained the desired results. “There were clear examples of him instructing people to manipulate data to fit the hypothesis,” one of the lab members says.

Science

The purist streak in economics

from Lars Syll

So in what sense is this “dynamic stochastic general equilibrium” model firmly grounded in the principles of economic theory? I do not want to be misunderstood. Friends have reminded me that much of the effort of “modern macro” goes into the incorporation of important deviations from the Panglossian assumptions that underlie the simplistic application of the Ramsey model to positive macroeconomics. Research focuses on the implications of wage and price stickiness, gaps and asymmetries of information, long-term contracts, imperfect competition, search, bargaining and other forms of strategic behavior, and so on. That is indeed so, and it is how progress is made …

There has always been a purist streak in economics that wants everything to follow neatly from greed, rationality, and equilibrium, with no ifs, ands, or buts. Most of us have felt that tug. Here is a theory that gives you just that, and this time “everything” means everything: macro, not micro. The theory is neat, learnable, not terribly difficult, but just technical enough to feel like “science.”

Robert Solow

Yes, indeed, there is a “purist streak in economics that wants everything to follow neatly from greed, rationality, and equilibrium, with no ifs, ands, or buts.” That purist streak has given birth to a kind of ‘deductivist blindness’ of mainstream economics, something that also to a larger extent explains why it contributes to causing economic crises rather than to solving them. But where does this ‘deductivist blindness’ of mainstream economics come from? To answer that question we have to examine the methodology of mainstream economics.

Economics and ideology

from Lars Syll

Mainstream (neoclassical) economics has always put a strong emphasis on the positivist conception of the discipline, characterizing economists and their views as objective, unbiased, and non-ideological …

Acknowledging that ideology resides quite comfortably in our economics departments would have huge intellectual implications, both theoretical and practical. In spite (or because?) of that, the matter has never been directly subjected to empirical scrutiny.

In a recent study, we do just that. Using a well-known experimental “deception” technique embedded in an online survey that involves just over 2400 economists from 19 countries, we fictitiously attribute the source of 15 quotations to famous economists of different leanings. In other words, all participants received identical statements to agree or disagree with, but source attribution was randomly changed without the participants’ knowledge. The experiment provides clear evidence that ideological bias strongly influences the ideas and judgements of economists. More specifically, we find that changing source attributions from mainstream to less-/non-mainstream figures significantly reduces the respondents’ reported agreement with statements. Interestingly, this contradicts the image economists have of themselves, with 82% of participants reporting that in evaluating a statement one should only pay attention to its content and not to the views of its author …

Economics education, through which economic discourses are disseminated to students and future economists, is one of these important channels. It affects the way students process information, identify problems, and approach these problems in their research. Not surprisingly, this training may also affect the policies they favor and the ideologies they adhere to. In fact, there already exists strong evidence that, compared to various other disciplines, students in economics stand out in terms of views associated with greed, corruption, selfishness, and willingness to free-ride …

We find evidence of a strong ideological bias among economists … For example, when a statement criticizing “symbolic pseudo-mathematical methods of formalizing a system of economic analysis” is attributed to its real source, John Maynard Keynes, instead of its fictitious source, Kenneth Arrow, the agreement level among economists drops by 11.6%. Similarly, when a statement criticizing intellectual monopoly (i.e. patent, copyright) is attributed to Richard Wolff, the American Marxian economist at the University of Massachusetts, Amherst, instead of its real source, David Levine, professor of economics at the Washington University in St. Louis, the agreement level drops by 6.6%.

Mohsen Javdani & Ha-Joon Chang

Economics and the way the world works

from Lars Syll

With any phenomenon of interest, understanding its nature or essential properties allows us to relate to, or interact with, it in more knowledgeable and competent ways than would otherwise be the case …

A surprising number of social theorists, when embarking on substantive analyses, pay almost no attention at all to insights bearing on the nature of these (or any other) factors. Instead, the preferred option is to select the types of methods, procedures or tools to be employed before, and quite independently of, knowing the task to be undertaken, the nature of the phenomena involved, the context or any other specifics of the situation …

This is the case of modern academic economics. Economists do indeed widely suppose, prior to undertaking any analysis that there is one specific way of proceeding that is appropriate for all occasions … This is to employ methods of mathematical modelling …

The discipline has failed to provide significant insight for the last 60 years or  more … This persistent failure is indeed to a very large extent the result of sustained ontological neglect.

The kinds of laws and relations that economics has established, are laws and relations about entities in models that presuppose causal mechanisms being atomistic and additive. When causal mechanisms operate in the real world they only do it in ever-changing and unstable combinations where the whole is more than a mechanical sum of parts. If economic regularities obtain they do it (as a rule) only because we engineered them for that purpose. Outside man-made ‘nomological machines’ they are rare, or even non-existent. Unfortunately, that also makes most of the achievements of contemporary economic theoretical modelling — rather useless.

The current state of game theory

from Lars Syll

Back in 1991, when yours truly earned his first PhD​ with a dissertation on decision making and rationality in social choice theory and game theory, I concluded that “repeatedly it seems as though mathematical tractability and elegance — rather than realism and relevance — have been the most applied guidelines for the behavioural assumptions being made. On a political and social level, ​it is doubtful if the methodological individualism, ahistoricity and formalism they are advocating are especially valid.”

This, of course, was like swearing in church. My mainstream colleagues were — to say the least — not exactly überjoyed.

For those of you who are not familiar with game theory, but are eager to learn something relevant about it, I have three suggestions:

Start with the best introduction there is

then go on to read more on the objections that can be raised against game theory and its underlying assumptions, e.g. rationality, ‘backward induction’ and ‘common knowledge’ in

The misuse of mathematics in economics

from Lars Syll

Many American undergraduates in Economics interested in doing a Ph.D. are surprised to learn that the first year of an Econ Ph.D. feels much more like entering a Ph.D. in solving mathematical models by hand than it does with learning economics. Typically, there is very little reading or writing involved, but loads and loads of fast algebra is required. Why is it like this? …

One reason to use math is that it is easy to use math to trick people. Often, if you make your assumptions in plain English, they will sound ridiculous. But if you couch them in terms of equations, integrals, and matrices, they will appear more sophisticated, and the unrealism of the assumptions may not be obvious, even to people with Ph.D.’s from places like Harvard and Stanford, or to editors at top theory journals such as Econometrica …

Given the importance of signaling in all walks of life, and given the power of math, not just to illuminate and to signal, but also to trick, confuse, and bewilder, it thus makes perfect sense that roughly 99% of the core training in an economics Ph.D. is in fact in math rather than economics.

Douglas L. Campbell

Indeed.

No, there is nothing wrong with mathematics per se.

No, there is nothing wrong with applying mathematics to economics.

Mathematics is one valuable tool among other valuable tools for understanding and explaining things in economics.

What is, however, totally wrong, are the utterly simplistic beliefs that

The ultimate methodological issue in economics

from Lars Syll

If scientific progress in economics — as Robert Lucas and other latter-day followers of Milton Friedman seem to think — lies in our ability to tell ‘better and better stories’ one would of course expect economics journals to be filled with articles supporting the stories with empirical evidence. However, the journals still show a striking and embarrassing paucity of empirical studies that (try to) substantiate these stories and their predictive claims. Equally amazing is how little one has to say about the ultimate methodological issue — the relationship between the model and real-world target systems. It is as though explicit discussion, argumentation and justification on the subject aren’t considered required.

If the ultimate criteria of success of a model is to what extent it predicts and coheres with (parts of) reality, modern mainstream economics seems to be a hopeless misallocation of scientific resources. To focus scientific endeavours on proving things in models is a gross misapprehension of what an economic theory ought to be about. Deductivist models and methods disconnected from reality are not relevant to predicting, explaining or understanding real-world economies.

If macroeconomic models – no matter what ilk –  build on microfoundational assumptions of representative actors, rational expectations, market clearing and equilibrium, and we know that real people and markets cannot be expected to obey these assumptions, the warrants for supposing that conclusions or hypotheses of causally relevant mechanisms or regularities can be bridged, are obviously non-justifiable.