Many social sciences use a model of “rational actors” that completely think through options and make decisions consistent with their preferences. This model of human decision making is particularly prevalent in the field of economics, where it underlies most of the results and thinking. However, many other social scientists strongly dislike this model of decision making, arguing that it is has unrealistic expectations on humans and is demonstrably false. They argue that the rational actor model has humans thinking through infinite streams of “what would he do” arguments, perfect and extensive knowledge about their environment, and otherwise complicated thinking required to be rational. They also cite numerous studies that are mostly in psychology and even behavioral economics that illustrate cognitive biases and other instances where people act irrationally.
What follows is some of my thoughts about the utility and usefulness of the rational actor model of human decision making.
First, it is valuable to separate two ways that the rational actor model is used: as a normative and as a descriptive model. As a normative model, the rational actor model illustrates one recommendation for how decisions *should* be made. Many people generally consider rational decisions to be the “best” or “most correct” decisions because they take into account all of the different factors that influence the decisions and balance them appropriately. Economists will often point out that irrational decisions open up the opportunity for arbitrage: taking advantage of the decision maker’s irrationality through repeated interactions.
While many people may (at least reluctantly) agree with the rational actor model as a normative model of decision making, many fewer people believe the rational actor model is accurate as a descriptive model. Indeed, as a description of *how* decisions are made it is almost certainly false. Most people need to be trained (often through economics courses) to be able to think through what a “rational” actor would do; they do not do so naturally. It is unreasonable, therefore, to believe that most people actually do think through decisions using this complicated “rational” way of thinking.
However, just because they don’t necessarily *think* rationally doesn’t mean that they don’t *act* rationally. There are many outside influences on behavior that may have shaped human behavior towards rationality without cognitively being rational. Indeed, if the rational actor model is a good normative model, it would make sense for humans to end up figuring out ways to act rationally even without thinking rationally. It is plausible that evolution has shaped a number of human behaviors to be rational. When you think about it, it makes sense for evolution to shape much human behavior to be as optimal (rational?) as possible without requiring overly-costly thinking; rational behavior without the difficulty of rational thinking could easily be an optimal outcome of evolutionary processes. Additionally, there are many equilibrium process — arbitrage, competition, etc. — that further shape behavior towards rationality. Indeed, many behaviors are well-approximated by the rational actor model, including but not limited to many market behaviors such as price/quantity predictions, macro-scale economies, etc..
The fields of psychology and behavioral economics has done an excellent job document a wide variety of *cognitive biases*: patterns in human decision making that consistent deviate from the rational actor model. It is true that the rational actor model is not a perfect theory of human behavior; however it does apply in many situations. I think a good analog is Newton’s theory of motion. Newton theory of motion isn’t a description of how objects decide where to go; it is simply a description of the result behavior. Planets don’t use Newton’s equations to decide where to go next, but Newton’s equations are still effective at predicting where the planets will be tomorrow nevertheless. This is similar to the rational actor model: the RAM doesn’t necessarily say how humans come to their decisions, but it does accurately predict what those decisions will be.
Newton’s theory of motion is also a good analog for another reason: it too is imperfect. There are many things that Newton’s theory gets wrong, particularly at the extremes when objects are moving very fast (relativity) or are very small (quantum mechanics). But just because it is imperfect doesn’t make it useless; it is still a very useful theory for predicting the behavior of objects in motion in many circumstances, and is still taught in school for that very reason. For many years (centuries?) there were acknowledged flaws in Netwonian mechanics, but still it was the dominant theory because it was useful and no better theory existed.
I believe the rational actor model is very similar. Yes, there are numerous acknowledged flaws in the theory; people do not always behavior rationally. However, right now it is still the best and most comprehensive model of human decision making that we have. Many scientists are striving to figure out just when and were the model works well, and when and where it should not be used. I suspect that at some point there will be a Kuhn-ian paradigm shift where a new model of decision making will supplant the RAM as the primary / best model of human decision making, must like relativity and quantum mechanisms supplanted newtonian mechanics. But until this new theory emerges, the rational actor model is still the best model.
(And now this is when this essay becomes particularly defensive.) There are many critics of the rational actor model. Indeed, I have had entire papers rejected simply because I used the rational actor model, which the reviewers believes was “wrong”. Yes, the rational actor model has flaws, but so does any theory. What most critics fail to do is to argue that either a) there exists a better / more useful theory of human decision making that should be used instead, or that b) not having a theory, and not making predictions, is better than using the rational actor model. Obviously, if the predictions are completely wrong, then b) is true. The “Rick Wash” theory of decision making (where I assume that everyone would make the same decision that I think I would make in that situation) is an incorrect theory of behavior, and probably leads to so many incorrect predictions that not having a theory is better than using the “Rick Wash” theory. However, the rational actor model has proven to be quite useful in many situations. It has been immensely useful in understanding the behavior of markets, in understanding political relationships and behavior between and within nation-states, and in understanding behavior within organizations. Much of the advise used to make major decisions for our economy is based on predictions from the rational actor model.
As a theory of human decision making, the rational actor model is certainly not perfect. It does not explain *how* decisions are made, and it doesn’t accurately describe all human decisions. However, it is a very useful model of behavior because it provides strong and simple guidance on how to think through decisions in a way that provides reasonable and relatively accurate predictions about complicated human behaviors.
Many social sciences use a model of “rational actors” that completely think through options and make decisions consistent with their preferences. This model of human decision making is particularly prevalent in the field of economics, where it underlies most of the results and thinking. However, many other social scientists strongly dislike this model of decision making, arguing that it is has unrealistic expectations on humans and is demonstrably false. They argue that the rational actor model requires humans to think through infinite streams of “what would he do” arguments, have perfect and extensive knowledge about their environment, and otherwise use complicated thinking patterns. They also cite numerous studies that are mostly in psychology and even behavioral economics that illustrate cognitive biases and other instances where people act irrationally.
What follows is some of my thoughts about the utility and usefulness of the rational actor model of human decision making.
First, it is valuable to separate two ways that he rational actor model is used: as a normative and as a descriptive model. As a normative model, the rational actor model illustrates one recommendation for how decisions should be made. Many people generally consider rational decisions to be the “best” or “most correct” decisions because they take into account all of the different factors that influence the decisions and balance them appropriately. Economists will often point out that irrational decisions open up the opportunity for arbitrage: taking advantage of the decision maker’s irrationality through repeated interactions.
While many people may (at least reluctantly) agree with the rational actor model as a normative model of decision making, many fewer people believe the rational actor model is accurate as a descriptive model. Indeed, as a description of how decisions are made it is almost certainly false. Most people need to be trained (often through economics courses) to be able to think through what a “rational” actor would do; they do not do so naturally. It is unreasonable, therefore, to believe that most people actually do think through decisions using this complicated “rational” way of thinking.
However, just because they don’t necessarily think rationally doesn’t mean that they don’t act rationally. There are many outside influences on behavior that may have shaped human behavior towards rationality without cognitively being rational. Indeed, if the rational actor model is a good normative model, it would make sense for humans to end up figuring out ways to act rationally even without thinking rationally. It is plausible that evolution has shaped a number of human behaviors to be rational. When you think about it, it makes sense for evolution to shape much human behavior to be as optimal (rational?) as possible without requiring overly-costly thinking; rational behavior without the difficulty of rational thinking could easily be an optimal outcome of evolutionary processes. Additionally, there are many equilibrium process — arbitrage, competition, etc. — that further shape behavior towards rationality. Indeed, many behaviors are well-approximated by the rational actor model, including but not limited to many market behaviors such as price/quantity predictions, macro-scale economies, etc..
The fields of psychology and behavioral economics has done an excellent job document a wide variety of cognitive biases: patterns in human decision making that consistent deviate from the rational actor model. It is true that the rational actor model is not a perfect theory of human behavior; however it does apply in many situations. I think a good analog is Newton’s theory of motion. Newton theory of motion isn’t a description of how objects decide where to go; it is simply a description of the result behavior. Planets don’t use Newton’s equations to decide where to go next, but Newton’s equations are still effective at predicting where the planets will be tomorrow nevertheless. This is similar to the rational actor model: the RAM doesn’t necessarily say how humans come to their decisions, but it does accurately predict what those decisions will be.
Newton’s theory of motion is also a good analog for another reason: it too is imperfect. There are many things that Newton’s theory gets wrong, particularly at the extremes when objects are moving very fast (relativity) or are very small (quantum mechanics). But just because it is imperfect doesn’t make it useless; it is still a very useful theory for predicting the behavior of objects in motion in many circumstances, and is still taught in school for that very reason. For many years (centuries?) there were acknowledged flaws in Netwonian mechanics, but still it was the dominant theory because it was useful and no better theory existed.
I believe the rational actor model is very similar. Yes, there are numerous acknowledged flaws in the theory; people do not always behavior rationally. However, right now it is still the best and most comprehensive model of human decision making that we have. Many scientists are striving to figure out just when and were the model works well, and when and where it should not be used. I suspect that at some point there will be a Kuhn-ian paradigm shift where a new model of decision making will supplant the RAM as the primary / best model of human decision making, must like relativity and quantum mechanisms supplanted newtonian mechanics. But until this new theory emerges, the rational actor model is still the best model.
(And now this is when this essay becomes particularly defensive.) There are many critics of the rational actor model. Indeed, I have had entire papers rejected simply because I used the rational actor model, which the reviewers believed was “wrong”. Yes, the rational actor model has flaws, but so does any theory. What most critics fail to do is to argue that either a) there exists a better / more useful theory of human decision making that should be used instead, or that b) not having a theory, and not making predictions, is better than using the rational actor model. Obviously, if the predictions are completely wrong, then b) is true. The “Rick Wash” theory of decision making (where I assume that everyone would make the same decision that I think I would make in that situation) is an incorrect theory of behavior, and probably leads to so many incorrect predictions that not having a theory is better than using the “Rick Wash” theory. However, the rational actor model has proven to be quite useful in many situations. It has been immensely useful in understanding the behavior of markets, in understanding political relationships and behavior between and within nation-states, and in understanding behavior within organizations. Much of the advise used to make major decisions for our economy is based on predictions from the rational actor model.
As a theory of human decision making, the rational actor model is certainly not perfect. It does not explain how decisions are made, and it doesn’t accurately describe all human decisions. However, it is a very useful model of behavior because it provides strong and simple guidance on how to think through decisions in a way that provides reasonable and relatively accurate predictions about complicated human behaviors.