How do we know other minds?

When we look or converse with other humans we immediately assume that they are conscious like us; that they see red as red, feel emotion like us and can understand their own thoughts. We assume others have minds like ours yet we have no direct access to their mind. How this is the case and how we access other minds has been a debate among philosophers for many years. Husserl claimed that we note similar behaviour and infer other minds; whilst Satre claimed we had a more direct access to them. In more recent times Cognitive Scientists and Neuroscientists have entered the debate. Two well known theories have emerged from the debate; "Theory" theory, and "Simulation" theory.

"Theory" theory makes use of theory of mind (TOM), and fits in quite well with Husserl’s account. We observe others behaviour and then postulate or infer causal mental states that must be behind such actions. We naturally think in very mentalistic ways because of our immersion in language. We take a folk psychological understanding in our everyday intuitions of others behaviour. Thus we say things like; “Jim went to the shop because he believed they had orange juice for sale and he desired to quench his thirst.” Fodor claims that we can't imagine humans, as such socio-linguistic beings, not thinking in mentalistic terms and using a strong TOM.

Supporters of the theory claim that there is a special purpose mechanism in the brain that facilitates the process. Autistics are said to have a minimal TOM due to a defect in this brain mechanism. On the other hand Williams Syndrome patients who are very social (good TOM) but lack good general intelligence are said to have a well developed mechanism. However the details of such a mechanism are unclear and the theory has received much criticism for being overly mentalistic in its assumptions.

The other theory; “Simulation” theory, claims we have a more direct cognitive access to other minds, which is less inferential and more instinctive. It claims when we see the actions of others we use our brains to simulate their minds . We postulate differences between ourselves and others and incorporate such factors into our simulations. The theory is not that dissimilar to TOM but implies a greater disassociation from personal perspective and greater emphasis on the perspective of the other, and thus is thought to account for empathy more. However both theories make large reference to mentalistic abstracta.

I would argue that it depends on the individual and situation in a real world context as to which method is used. Once again I am placing great emphasis on taking embodiment into account.

Certain people in certain situations might think about others actions by actually postulating the beliefs behind them ("Theory" theory). We can certainly imagine someone consciously thinking; “Jim is going to the shop because he thinks/believes he can get a drink there and he desires to quench his thirst.” My intuition however is that most people in most situations don’t go through such rigorous inferences (I know I certainly don’t most of the time.)

Other people in other situations might try to simulate the mind behind the actions of a good friend perhaps. For example upon seeing a friend crying one might put themselves in their friends shoes, so to speak, and think about what things might make that friend cry. Thus by realising a more direct access one could understand related emotions and empathize to a greater extent. Once again though my intuition is that a lot of the time we don’t go as far as this. If we did it all the time then we would be using up an awful lot of brain power that could otherwise be avoided. We have to take into account that such mechanism came to be via natural selection, and thus brain power usage is a factor.

More recently, neuroscientific works into the mechanics of mirror neurons lead to a more detailed view on the issue. Thompson and Gallagher (1999) argue that following perception of others actions, mirror neurons (found in the ventral premotor cortex of monkeys) are simulated which gives a direct access to other minds. This evolved mechanism means that usually no inference is necessary; saving precious brain power. It is as simple as an action observed – simulation triggered reflex. When we see another in pain we don’t go through long and unnecessary inferences; we feel empathy towards them due to the triggering of mirror neurons. Think of when you see someone really hurt themselves and it makes you squirm; it almost feels like you feel their pain. The explanation for this is mirror neuron theory.

The leading neuroscientist V.S.Ramachandran argues that this mechanism would have originally evolved for social dynamics and later caused self reflection of own intentions leading to a theory of mind. It is certainly true that social species require such a mechanism and we can’t imagine them having a strong TOM before language evolved. Primate faces can show a lot of information in the way they are expressed. Thus individuals by looking at others facial expression can gain access to their emotions using mirror neuron mechanism. This sharing of information increases social dynamics and chances of survival for the group. It also decreases IP load on inferential modules that can then be freed up for other functions. Language is the vehicle of mentalistic cognition and so before is evolution other mechanism would be crucial for survival and social dynamics.

Supporters of the theory admit that at times we do use more complex inference mechanism when we want to work out more precise details of other minds. Thus at times we do use something like “Theory” theory or “Simulation” theory. But through embodied practise during development, most of knowing other minds is automated into the mirror neuron system. It also provides an empirical explanation for autistic brain area deficiency (although this hypothesis is still under study). Thus I conclude that Mirror Neuron Theory really seems to be the key to our understanding on the issue.