## Wednesday, October 5, 2011

### Are we agile yet? Applying fuzzy logic to the manifesto

Some background on logic from my brother who is a math professor:

In Greek logic (the logic of Plato and Aristotle) there are only two truth values. Any statement is either true, or false, but not both. Truth is absolute. This works nicely except for when we say things like:
"This sentence is false"
If this statement is true, then it is also false, and if it is false, then it is also true, and if it is true, then it is also false - a 'fun' logical circle which causes trouble for Greek logic. This liar's paradox was ignored for about 2500 years. Since sentences are either true or false, then the sentence above obviously isn't a sentence. Case closed.

In the last century, mathematicians started to realize that things were not so simple. A quote from my brother:
"There are contradictions in the laws of physics – We have Einstein’s relativity that explains planetary motion, gravity, all these big things. And we have quantum mechanics that explains subatomic energy and matter, all those tiny things. Unfortunately, they contradict each other in the middle. Because the one requires physical reality to be absolutely smooth and continuous, while the other requires quantum bumps, which are profoundly non-smooth and discontinuous. Right now the laws of physics are both true and false (and by false, I mean true.)"
More common examples of statements that can be both true and false include: "I am young", "I am tall", and of course, "We are agile". Truth becomes fuzzy. The truth of those statements can lie somewhere in between absolutely false and absolutely true depending on who is saying them.
"A newborn is young" = truth value of 100%.
"A 20 year old is young" = truth value of 80%
Thus, fuzzy logic was born. Statements can have a truth value in between true and false.

Now let's apply this to the question "Are we agile yet?" by looking at the four tenants of the agile manifesto:
Individuals and interactions over processes and tools
Working software over comprehensive documentation
Customer collaboration over contract negotiation
Responding to change over following a plan
Many of us have read articles or have been in discussion groups where these statements are discussed at length and usually someone tries to apply Greek logic by making statements such as: "Agile has no documentation" and "Agile means no planning". However, the word "over" in the middle implies that fuzzy logic is at work. The manifesto authors are saying that for agile teams truth should be closer to the left than the right. We should focus more of our time on working software and less of our time creating documentation. Planning is still important but responding to change is more important so our plans need to be more flexible. For each statement, we want the left side to be more true than the right - the truth value should be above 50%. Additionally, having a truth value of 100% for any of the statements above can be a dangerous thing. We should stay fuzzy.

So when answering the original question for your team or organization - "Are we agile yet?" - don't expect a checklist of practices to give you the answer. Instead, ask your team this question: "Given the statements above, which direction are we moving?" If you are moving to the left and have committed to staying on the left side of each equation, then you've joined the club - you are agile. Agile is a direction, and that is absolutely true.