Probability Calculator

If you have problems clicking on UI or nodes in the WebGL version, maximize the screen (or use the download version).

About:

Probability Calculator was originally designed by Will Petillo to calculate p(doom) of AI destroying the world, but it is general enough to express any probabilistic mental model.  Use it to articulate your beliefs, see the implications of how those beliefs connect together, how your beliefs should update when something changes, and compare your mental models with others to quickly find the crux of your disagreements.

Controls:

[L Click] Select Source, [R Click] Select Target, [MM Drag] Pan View, [N] New Cell, [B] Branch (new + connect), [C] Connect / Disconnect, [X] Destroy, [F2] Recenter View

How to Use:

Create a set of nodes, set probabilities for each, and connect them in the style of a mind-map.  For leaf nodes—those with no inputs—set probabilities directly via a simple slider.  Branch nodes calculate probabilities based on their inputs. The set of inputs to a node can be combined via "intersection" or "union" and each individual input can be inverted.   These operations correspond to AND, OR, and NOT operations, and combining arbitrary numbers of nodes together allows for the full expressiveness of Boolean logic as applied to probability.

Apply biases to calculated nodes to express "unknown unknowns" in one's mental model.  Conjunctive bias acts like an additional input node that combines with the other inputs via intersection (an AND operation for probability).  By default, it is set to 1, which causes it to have no impact—it's like adding an additional requirement, but one that is certain to happen—and lowering it decreases the node's probability.  Disjunctive bias acts like an additional input node that combines with the others via union (an OR operation for probability).  By default, it is set to 0, which causes it to have no impact, and increasing it increases the node's probability.

Lastly, remember that while Probability Calculator demonstrates the implications of your beliefs, the nature of those beliefs is entirely up to you.  Set your probabilities wisely and defend your choices in each node's description.