This summary is a little difficult to write as I unfortunately do not feel that hyped about Mead. Who is Mead? What are some of his key ideas? What were some of the general movements that he was associated with?
Mead is famous for several concepts that draw on the tradition of social psychology. One of Mead's key idea is the notion of "taking the role of others". Basically, for Mead, thinking is a kind of inner conversation: by importing the attitudes of others into our conduct, we are able to view the world from the perspective of others. This is similar to the notion of the looking-glass self. Our perception of ourselves, thus, is constantly being shaped by society.
You can perhaps see why this is not very exciting: all these are fairly straightforward. What is slightly more exciting is Mead's idea of an I/me distinction. For Mead, there is no such thing as the "self". The highly mysterious, infamous "self" that we are supposed to find and discover from within (perhaps by traveling to India) is argued to be non-existent. In its place are two modes of selves - the 'I' and the 'me'. Mead conceives of the self as a social process whereby the self internalizes social attitudes and a 'me' and responds to it as an 'I'. In other words, the 'I' refers to the spontaneous, impulsive self that acts; the 'me', on the other hand, relates to the self-image when we look at ourselves through the eyes of others. According to Filipe, the "phase of the self that remembers is the 'I', the phase of the self which is remembered is the 'me'. These are not, however, two states of being: they are "processes within the larger process that is the self". The self is thus theorized to be in a perpetual state of flux - of remembering, acting and readjusting.
This duality in the conception of the self is rather radical, considering that it goes against the grain of mainstream discourse that assumes an essential self seated somewhere within our consciousness. For Mead, who and what we are develops not from the inside out, but from the outside in. While this may be true in general, Mead does not address the tricky notion of predispositions. How does Mead take into account certain character traits of children? What about the child predisposed to having an outgoing character? This is where Mead's theories of consciousness comes in. For Mead, consciousness precedes self. We can only have a "self" if we are conscious of ourselves. That is the reason why things without consciousness cannot have "selves", or at least, not the same kind of selves that we have.
In general, Mead's thinking is rather agreeable. It is not immensely fascinating, but it does have some quite interesting implications, one of which, as Filipe argues, has to do with the entire project of modernity. The other one is how it goes against the entire conception of the Cartesian rational self - before Mead, it seemed, reflectivity was not conceptualized as a social affair. That's why everyone talked about the brain in the vet, ghost in the shell, and all those stuff. Mead provides a good counter argument for the solipsism of philosophical skepticism.
The general arguments go like this. Skepticism is not entitled to reach the conclusion of "I think therefore I am" because in order for them to think in the first place, they need language. (Mead would argue that thoughts, or even a consciousness, is impossible without language - which is controversial.) And because of how language only came about due to a social process, thought, or reflectivity itself, can be conceptualized to be a social affair.
A skeptic may say: granted, a child trapped on an island alone from birth might not develop a language system, but surely he could develop a form of spacial awareness? Mead would say that there are two types of consciousness: consciousness as 'awareness', and consciousness as reflective intelligence. Without language, the first could still develop, but the second would have been impossible. An individual would never reach a type of reflective intelligence outside of society. Their "self" is necessarily one-sided.
