15 Easy Minsky Pieces

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Dr. Rus­sell Stan­dish and I have been work­ing on Min­sky now for almost two years now–ever since we received the $125K from INET’s Spring 2011 grant round: Rus­sell as builder (cod­ing in C++ and Tcl/Tk) and me as archi­tect (play­ing with each release, spot­ting bugs and sug­gest­ing fea­tures). It’s been a part-time endeav­or: Rus­sell, as a con­tract pro­gram­mer, has to keep more than one iron in the fire, while I have a fair few balls in the air myself. Rus­sell has put in about 2000 hours of cod­ing over that time, and we still have funds to sup­port about anoth­er 250 hours after the suc­cess­ful Kick­starter cam­paign ear­li­er this year.

That amount of cod­ing is chick­en feed com­pared to the mil­lions of hours that have gone into a stan­dard com­mer­cial prod­uct like Microsoft Word or Excel, so Min­sky is still rough at the edges, and lacks a num­ber of fea­tures that you would expect in a com­mer­cial package–for exam­ple, there is no Edit menu for copy­ing, cut­ting and past­ing (you have to con­trol all that via the right mouse but­ton), no Undo fea­ture, etc. There have been (and undoubt­ed­ly still are) many bugs too: things that should work don’t for all sorts of rea­sons. The com­put­er trade describes this phase of a pro­gram’s life as the “Pre-Alpha, Alpha and “Beta” release stages, when new fea­tures are added and only users who are will­ing to tol­er­ate crash­es should use the soft­ware.

But at some point enough core func­tion­al­i­ty and sta­bil­i­ty is in place for a first release, and I think that moment has arrived for Min­sky. From now on, there will be two forks for the pro­gram: the sta­ble “Pet­ty” release (named after the Eng­lish polit­i­cal econ­o­mist William Pet­ty), and the Beta builds for the next “Mun” release (named after the Mer­can­tilist Thomas Mun). We will fix any bugs that are iden­ti­fied in the Pet­ty release, but no new fea­tures will be added. They will turn up in the Mun release, with the pro­vi­so that with new fea­tures inevitably come new bugs as well: we real­ly want users to try this fork out, but on the pro­vi­so that you accept there will be bugs.

There is still only a rudi­men­ta­ry and incom­plete Help file (did I say I had too many balls in the air?), so to make up for it I’ve record­ed the fol­low­ing set of 15 videos that cov­er most of the fea­tures of the pro­gram. They’re all up on YouTube (where the num­ber is the series changes from 8 to 11 to 15…), but here they are for easy ref­er­ence, with some notes about what each video cov­ers. All the Min­sky (mky) files used in the pre­sen­ta­tions are in this Zip file.

So if you’re into eco­nom­ic mod­el­ing and you’d like to devel­op dynam­ic mon­e­tary mod­els, Min­sky now has enough fea­tures to be worth using–and it won’t face the lim­i­ta­tions that apply to more con­ven­tion­al sys­tem dynam­ics pro­grams, like Stel­la, Ven­sim, Vis­sim, etc., that make it inher­ent­ly chal­leng­ing to mod­el the finan­cial sys­tem. With Min­sky and its God­ley Tables, mon­e­tary mod­el­ing is a cinch (and it will get eas­i­er as we add more capa­bil­i­ties to the pro­gram). So please, down­load the pro­gram, join our beta-test­ing group, and start build­ing mon­e­tary macro­eco­nom­ics.

Minsky 1.0 Demo #1 Basics And Godley Table

Installing Min­sky from a ZIP file, the can­vas, wiring to build equa­tions, installing a graph, graph­ing a basic func­tion like sin(t), out­putting the equa­tions to LaTeX (which you can import into MathType in Word), and a basic “endoge­nous mon­ey” God­ley Table.

Min­sky Files: sine.mky (using Min­sky to plot a sine wave); Godley.mky (a basic pure­ly mon­e­tary mod­el, with no simulation–just the dou­ble-entry book­keep­ing table).

Minsky 1.0 Demo #2 Godley Simulation

Using a God­ley Table to define a numer­i­cal sim­u­la­tion: right-click to copy flows and vari­ables (“stocks”), defin­ing mon­e­tary equa­tions, and run­ning a sim­u­la­tion.

Min­sky file: GodleySim01.mky (the same mod­el as in the pre­vi­ous video with def­i­n­i­tions of flows added so that it can be numer­i­cal­ly sim­u­lat­ed).

Minsky 1.0 Demo #3 Godley-Goodwin Integration

Using time lags, enter­ing Greek char­ac­ters and sub­scripts, build­ing a dynam­ic mod­el using the flow­chart part of the pro­gram, using inte­gra­tion blocks in dynam­ic mod­els, mak­ing x‑y graphs as well as graphs of vari­ables against time.

Min­sky file: GodleySim02.mky (the same mod­el as in the pre­vi­ous video, but using time con­stants rather than arbi­trary num­bers for sys­tem para­me­ters); GodleyGoodwin01 and GodleyGoodwinSim01 (adding a Good­win mod­el of pro­duc­tion using the flow­chart aspects of the pro­gram, and adding XY charts, slow­ing down the sim­u­la­tion speed)

Minsky 1.0 Demo #4 Godley-Goodwin Integration

Start­ing to inte­grate a mon­e­tary and a phys­i­cal mod­el, using slid­ers to vary para­me­ters dur­ing a sim­u­la­tion.

Min­sky files: GodleyGoodwinSimInt01 (begin­ning to inte­grate the two mod­els: mak­ing the wage a mon­e­tary phe­nom­e­non)

Minsky 1.0 Demo #5 Godley Goodwin Integration #2

Doing it right: start­ing by mod­i­fy­ing the real cycli­cal mod­el to include mon­e­tary vari­ables.

Min­sky files: GodleyGoodwinSimInt01C (adding Price to the Good­win mod­el before attempt­ing the inte­gra­tion).

Minsky 1.0 Demo #6 Godley-Goodwin Integration

Con­tin­u­ing the process.

Min­sky files: GodleyGoodwinSimInt01D (com­plet­ing the inte­gra­tion)

Minsky 1.0 Demo #7 Godley-Goodwin Integration #4

Con­tin­u­ing the process.

Min­sky files include GodleyGoodwinSimInt03, where I add a lin­ear invest­ment func­tion to the lin­ear wage change func­tion that is the core of the Good­win mod­el.

Minsky 1.0 Demo #8 Godley-Goodwin Integration #5

Get­ting cycles in the mon­e­tary econ­o­my as well as the phys­i­cal. Intro­duc­ing an invest­ment func­tion as well as a wage change func­tion. Show­ing the debt-defla­tion mod­el.

Min­sky files include DebtDeflation02, which is the mon­e­tary ver­sion of my 1995 debt-cri­sis mod­el in “Finance and Eco­nom­ic Break­down”

Minsky 1.0 Demo #09 Multiple Godley Tables

Com­bin­ing MMT and MCT with two God­ley Tables, one for the Cen­tral Bank, the oth­er for Pri­vate Banks. Min­sky’s built-in log­ic to main­tain con­sis­ten­cy between assets and lia­bil­i­ties across mul­ti­ple God­ley Tables. A poten­tial­ly sur­pris­ing result about the rela­tion­ship between the change in pri­vate debt and the change in pub­lic debt.

Min­sky files: MinskyOnePointZeroDemo09MultipleGodleyTables (com­bines MMT and MCT and shows that the change in pri­vate debt and the change in pub­lic debt are not of equal and oppo­site mag­ni­tudes in a closed econ­o­my).

Minsky 1.0 Demo #10 Zooming

Group­ing enti­ties, zoom­ing in to see a group, edit­ing a group, using the Lorenz Strange Attrac­tor as first exam­ple, and my mod­el of debt-defla­tion as the sec­ond.

Minsky 1.0 Demo #11 Bugs

Bugs and how to cope with them.

Minsky 1.0 Demo #12 Lorenz model

Using the flow­chart side of the pro­gram to build the famous Lorenz mod­el. Chang­ing the Runge-Kut­ta para­me­ters to get a smoother sim­u­la­tion. Set­ting ranges on a graph.

Minsky 1.0 Demo13 # Lorenz model with Sliders

Using slid­ers to vary para­me­ters in a mod­el while it runs.

Min­sky files: Vari­a­tions on Lorenz, espe­cial­ly LorenzWithSliders02.

Minsky 1.0 Demo #14 Competitors

How does Min­sky stack up as a sys­tem dynam­ics pro­gram com­pared to the estab­lished play­ers Simulink, Ven­sim, and Vis­sim? It does­n’t have the pow­er of these estab­lished pro­grams of course–matching the fea­ture set of even Ven­sim would require tens thou­sands more hours of pro­gram­ming time, let alone that of Vis­sim or the mar­ket leader Simulink. But on a user-friend­li­ness scale, I think it’s easy to see that Min­sky is much eas­i­er to use than Ven­sim, sig­nif­i­cant­ly eas­i­er than Simulink, and with­in reach of Vissim–though it lacks some basic edit­ing fea­tures.

Minsky 1.0 Demo #15 Why Godley Tables?

This is the clinch­er. If you want to mod­el mon­e­tary dynam­ics, there is no oth­er pro­gram that offers any­thing like the God­ley Table for mod­el­ing the dou­ble-entry flows that char­ac­ter­ize the finan­cial sys­tem. A flow­chart is an inher­ent­ly weak tool for build­ing a mon­e­tary mod­el..