Leibniz
Scientific thinkers of the seventeenth- and eighteenth centuries in Europe described the universe as being like a gigantic, complex, smoothly-functioning watch. This implies, they argued, that the cosmos must have been made by the supreme watchmaker = God.
G W Leibniz, the inventor of calculus, offered the idea (later lampooned by Voltaire in Candide) that ours is also the best of all possible worlds. What about war, famine, disease, poverty…? Leibniz’ view is that though we can imagine a world like ours, only better, that thought-experiment world is not possible. Put a different way, Leibniz thought that behind the scenes God uses a calculus-like maximizing function for his creation. The total amount of goodness in the world is the highest it can be. Were we to make one existing bad thing better, other things would worsen enough that the sum total of good would be reduced.
Adam Smith
Around the same time Adam Smith introduced into economics basically the same idea, the “invisible hand” that directs individuals, all following their own self-interest, in a way that also somehow ends up serving the public interest. This idea, still a staple of economics and finance, has the same, ultimately theological, roots–that behind the scenes a benificent God is working to create the best possible outcome.
since then
The scientific world has moved on since Leibniz and Smith, thanks to Hegel/Marx (social evolution), Schopenhauer (collective unconscious), Darwin (natural evolution), Kierkegaard (God of religion vs. god of science), Nietzsche (change without progress) and Freud (individual unconscious).
Twentieth-century physicists, starting with Einstein, have suggested that the universe is in fact messier and more unruly than Newton thought.
Nevertheless, the laissez faire assumption of the invisible hand that makes everything ok remains a key element of economic and financial theorizing.
Modern Portfolio Theory
Invented by academics over fifty years ago, MPT is what every MBA student learns in business school. Its main conclusion is that the highest value portfolio (i.e., the best of all possible portfolios) is the market index. A cynic might argue that the main attraction of a theory that says practical knowledge or experience in financial markets is useless is that it suits the interests of professors who possess neither.
However, the conclusion is not just convenient for the educational establishment. It also fits squarely into the 18th century European Enlightenment view of the “invisible hand” guiding the market.
MPT requires a bunch of counter-intuitive assumptions, summed up in the efficient markets hypothesis, including that:
–everyone acts rationally
–everyone has the same information
–everyone has the same investment objectives
–everyone has the same investment time frame
–everyone has the same risk tolerances
–there are no dominant, market-moving players.
Granted all this, one can argue that any portfolio that differs from the market will be worse than the market.
The standard criticism of MPT is that it ignores the bouts of greed and fear that periodically take control of markets. In fact, even while MPT was being formulated, markets were being roiled by the conglomerate mania of the late Sixties, the Nifty Fifty mania of the early Seventies and the wicked bear panic of 1974, when stocks were ultimately trading below net cash on the balance sheet and still went down every day.
Arguably anyone looking out an ivory tower window should have noticed that MPT had no way of talking about the crazy stuff that was roiling Wall Street almost constantly during that period–and which showed its assumptions were loony. Nevertheless, theology trumped the facts.
today
In a way, MPT suits me fine. The fewer people looking for undervalued companies the easier it is for the rest of us to find them.
However, one basic high-level assumption that even professional investors still make is that the economic/political system in the US functions relatively prudently and therefore the economy remains more or less stable. But in essence this is only a different way of saying the “invisible hand” guides self-interest-seeking individuals in politics toward a socially beneficial result.
I’m not sure that’s true anymore, if it ever was. For one thing, Washington has relied almost exclusively on monetary policy to fine-tune the US economy over the past generation–encouraging all sorts of unhealthy financial speculation and intensifying social inequality. Washington has also done less than the ruling body of any other developed country to help citizens cope with dramatic structural economic changes over the past twenty years. Resulting dissatisfaction has caused the rise to power of newcomers like Donald Trump who have pledged to address these issues but whose racism, venality and stunning incompetence appear to me to be doing large-scale economic and political damage to the country.
This development presents a significant issue for laissez faire theorists in the way deep emotionally-driven market declines do for the efficient markets hypothesis. As a practical matter, though, the situation is far worse than that: recent events in the US and UK illustrate, populating the halls of economic and political power with self-serving incompetents can do extraordinary amounts of damage. Left unchecked, at some point this has to have a negative effect on stock returns.