The problem of other minds is a philosophical problem traditionally stated as the following epistemological question: "Given that I can only observe the behavior of others, how can I know that others have minds?"[1] The problem is that knowledge of other minds is always indirect. The problem of other minds does not negatively impact social interactions due to people having a "theory of mind" – the ability to spontaneously infer the mental states of others – supported by innate mirror neurons,[2] a theory of mind mechanism,[3] or a tacit theory.[4] There has also been an increase in evidence that behavior results from cognition which in turn requires consciousness and the brain.
It is a problem of the philosophical idea known as solipsism: the notion that for any person only one's own mind is known to exist. The problem of other minds maintains that no matter how sophisticated someone's behavior is, that does not reasonably guarantee that someone has the presence of thought occurring within them as when oneself engages in behavior.[5] Phenomenology studies the subjective experience of human life resulting from consciousness. The specific subject within phenomenology studying other minds is intersubjectivity.
In 1953, Karl Popper suggested that a test for the other minds problem is whether one would seriously argue with the other person or machine [6]: "This, I think, would solve the problem of 'other minds'....In arguing with other people (a thing which we have learnt from other people), for example about other minds, we cannot but attribute to them intentions, and this means mental states. We do not argue with a thermometer."