# Rational irrationality of emotions and simulated annealing

When a colleague of mine stated that "emotions are life's simulated annealing" I found that idea very interesting. In order to explain why let me describe briefly the optimization algorithm known as "simulated annealing".

In many computer applications the essential calculation is minimization of a function, that is, finding the lowest point on a graph like this:

When trying to minimize a function the most rational thing seems to be go downhill from a random point until reaching the bottom. The problem with this approach is that you are likely to reach a local minimum, not the global one. The solution would seem optimal, but it's not likely to be optimal.

In order to avoid getting stuck in a local minimum a "simulated annealing" algorithm was developed that combines the rational downhill descent with irrational jumps away from the apparently optimal solution. The black arrows in the image below represent rational moves downhill, and the red arrow represent an irrational jump uphill:

sa2 http://www.iasor.tu-clausthal.de/Arbeitsgruppen/Stochastische-Optimierung/forschung/Bilder/Stochopt/SimAnnIdee_einf.jpg

It turns out that one often gets the best result by starting out with relatively frequent irrational jumps and then slowly reduces the frequency of irrational jumps in favor of rational descent. Start from chaos alternating with reason, then slowly reduce chaos and increase reason, and that would lead you to a better result than reason alone.

What my colleague probably meant is that human behavior seems to be akin to simulated annealing, that our emotions are akin to the irrational jumps away from the goal, and that these irrationalities somehow enhance our ability to reach the optimal goal. And just as in simulated annealing, we start in life by applying irrational emotions more frequently than rational thought, but as we grow up we slowly reduce irrational behavior and start applying reason more frequently.

Thus a couple of questions:

1) Does the above analogy have a merit?

2) Assuming the affirmative answer to the above, is that possible that human emotions have developed alongside with reason as an aid for reaching globally optimal results?

This is essentially what happened to Archimedes when he shouted "Eureka!".

Archimedes is stuck on a problem, he can't think of a solution (rational). So he has a bath to relax (emotive) and this leads to a (rational) solution which he would otherwise have missed.

This part of it is fine. But you should be very careful not to stretch the analogy too far:

1. I would take issue with the idea of human life as being an optimisation process - it models mankind as Homo Economicus - an idea that has been widely critiqued.

2. The role of emotions is much wider than solving problems, they play a huge part in society and our lives. Emotions can be ends in themselves.

3. Emotions are not particularly random. They in-fact push are behaviour in very specific directions (re. your question number 2: these directions have been selected for during human evolution).

4. There are other sources of randomness and spontaneity that can be part of cognitive processes.

5. Life is an on-going process. What points in time count as optima, what counts as transitions? It the utility function static, or does it change as we develop different goals and purposes?

6. It's not clear that we reach, or even aim for, global optima (see 1.). Better optima, perhaps. What are these global optima, and for that matter...

7. What is it that these utility functions are supposed to describe anyway?