There’s a kind of primitive variable that probably everyone who writes computer code knows and understands these days…the Boolean. Unlike other variables which can hold a range of values, be they numbers, or strings of ascii characters, the Boolean is a relentlessly either-or variable. And for that reason, it maps pretty well to the fundamental logic by which all digital computers operate, and to their smallest unit of data, the bit. But humans have been considering their world in Boolean logic ever since our minds first emerged from out of the biological background noise.<\/p>\n
Yes-No. True-False. Right-Wrong. Good-Bad.<\/em> Even as we admit to ourselves that there are often only shades of gray, we persist in reducing our experiences to these terms. It’s as basic an evaluation as can be. The second postulate of Aristotelian logic is that of ‘either-or’. A thing cannot both be, and at the same time not be. Either yes, or no. Either true, or false. Either right, or wrong. Either it is, or it is not. It must be one or the other.<\/p>\n Well…tell it to Schrodinger’s cat. It’s probably no coincidence that our machines are made in our image, that they resemble the way our minds like to think. The canvas always speaks of the artist. But as it turns out, that’s not actually the way our brains operate. It may not even be the way nature, at its most elemental level, works. There’s this intriguing tri-position logic in the natural world that I keep seeing raise its hand and wave at us from time to time. But it seems to go unexamined most of the time, and I think that’s because like the extra space-time dimensions physicists keep telling us are there, it’s hard for our minds to wrap themselves around it. And that’s really interesting, because one place you really see this tri-position logic is in how our brains actually physically work.<\/p>\n Consider the humble synapse. It is the gap between brain cells, across which two different kinds of chemical "messages" can cross. One kind of chemical causes the cell on the other side of the gap to fire. The other chemical inhibits the cell on the other side of the gap from firing. So far, so good. We’re still comfortably in the basic Boolean logic of things. Fire-Don’t fire. Yes-No. Off-On. Either-Or. But there’s a third thing that synapse can do: Nothing<\/em>.<\/p>\n So synapse logic has three states, not two. Fire, don’t fire, and…what? Here’s where it gets interesting for me. What is the word here. We don’t really have one. And that I think, is because the concept is difficult for us. The state itself seems foreign enough to the way our minds naturally work, that as far as I know, humans don’t really have a good enough word for that third position. Neutral doesn’t quite do it. It isn’t that it isn’t engaged, like a gear shift you put into neutral, say. It’s connected, to the rest of the brain. ‘Off’ isn’t quite it either. Each half of the synaptic gap has a current state that influences the state of the cells on either side of the synaptic gap depending on the direction of the message, or the absence of one. So there are really three states possible here: Fire, don’t fire, and a third, that is neither fire or don’t fire. Depending on the state of the synapses it’s connected to, a brain cell may or may not fire. So the cell itself may have just two states. But the synapses have three.<\/p>\n Our minds just don’t seem to grasp that third logical state very well, and we fumble to describe it. It’s a between state. No…it’s a middle state. Wait…a transitional state… Uhm… No…it’s…it’s… (shrug) I dunno…<\/em><\/p>\n Maybe ‘zero’ is the right way to think about it. But I can only say that because I write software code and I understand how zero is actually something distinct from a positive value, is distinct from a negative value. But that seems to be a non-intuitive concept for us humans. Consider that the Arabic invention of the zero as a form of notation actually came well after a lot of other very basic mathematical concepts. Well of course everyone knew that you can have a zero quantity. But expressing it abstractly seemed to be a difficulty. And in many programming languages, 0 evaluates to false anyway, and any other value is true (except in Basic, where –1 is (was) true, which I think is right from a bitwise NOT sense…but don’t get me started…). And…this third position isn’t really a ‘nothing’. It’s more of a ‘neither’. <\/p>\n