Robert B. "Bob" Brandom is an American philosopher best known for his work in the philosophy of language. He earned a B.A. in Philosophy from Yale University and a Ph.D. in Philosophy from Princeton University (writing his dissertation under Richard Rorty). He teaches at the University of Pittsburgh and, together with his collegue John McDowell, has come to be known as the figurehead of the so-called Pittsburgh Idealist movement in analytic philosophy of language. This movement is known for transposing lessons from the German philosophers Immanuel Kant and Georg Wilhelm Friedrich Hegel into an analytic tradition where these figures had for a century been largely ignored--if not actively disparaged.
Brandom is best known for his 1994 work, Making It Explicit: Reasoning, Representing, and Discursive Commitment. In this 700+ page opus, Brandom develops in systematic form his philosophy of language (of which more below). Brandom's Articulating Reasons: An Introduction to Inferentialism, from 2000, is a much shorter and more accessible restatement of some core ideas from Making It Explicit.
Other noteworthy works by Brandom include 2008's Between Saying and Doing: Towards an Analytic Pragmatism and 2019's A Spirit of Trust: A Reading of Hegel's Phenomenology. Brandom has also published numerous essays, many of which have subsequently been collected in their own volumes.
To get a taste of Brandom's philosophy, it is perhaps best to summarize the core movement throughout Making It Explicit (at least insofar as a 700+ page book can be boiled down to only one movement).
The question Brandom sets out to answer can best be described as 'What is meaning' or 'What is meaningfulness'. In this context, the words 'meaning' and 'meaningfulness' are used in the sense whereby words and other symbols can be meaningful. However, for Brandom there is an implicit understanding that this linguistic sense of 'meaning(fulness)' is intimately bound up with a more humanistic sense whereby our lives and relationships can be meaningful.
Before we begin to understand Brandom's answer to this question, it is worth understanding a popular answer to this question that is also the most prominent answer in current academic discussions.
This answer begins by noting the obvious point that we as humans find ourselves with access to both a subjective reality (in the form of our minds) and an objective reality (in the form of the external world). Given this state of affairs, it is only natural to want our two realities to be in proper relationship with one another. The fact that we all have bodies and most of us have voluntary control over many aspects of our bodies means that we usually have the ability to shape the world in relation to our minds (for good or for ill). Alternatively, it is our language and the higher-order thinking it makes possible that gives us the complementary ability to shape our minds in relation to the world (both truthfully and fallaciously).
For many people it is but a small step to generalize this latter point, and to say that the purpose of language is to represent the external world. Individual words, phrases, sentences, etc. are then understood to be meaningful insofar as they represent physical objects, relations, states of affairs, etc. that could exist in the real world. According to this answer, to understand the meaning of a word is at base to understand what object(s) it refers to; to understand the meaning of a full sentence is to understand whether that sentence is true or false.
Brandom's response to this representationalist account of meaning is not to say that it is wrong per se; instead he argues that it both overgeneralizes and underexplains.
Brandom's argument that the representationalist account overgeneralizes is usually the easier to understand, so let's start there. It begins by making the intuitive point that there are simply some words that don't seem to represent anything in particular.
On the concrete end of the spectrum, when you utter a word like 'ouch' you're not really using it to represent the pain that you are feeling. You don't "have time" to think the entire thought that you're in pain--you're just in pain gosh darnit.<.p>
Alternatively, an abstract word like 'if' doesn't so much represent something as offer you a way of relating different representations one to the other. Metaphorically speaking, the word 'if' isn't like any particular frame in a film; it's like the motion one sees between the frames when they're played back properly.
From here, Brandom argues that although one could try to squeeze these words (and others like them) into the shape left by the representationalist account, such a move is going to be clumsy at best and simply wrong at worst. Therefore, it's better to just take the lack of fit at face value and try to come up with a better, non-representational account of them.
As for the argument that the representationalist account underexplains, Brandom begins by arguing that the point of any account of meaning is to explain not just that words have meaning--that much is obvious to anyone who speaks a language. Instead, such an account needs also to explain how and why words have meaning. These are the difficult, properly philosophical questions.
To give the representationalist account its best shot of answering these deeper questions, let's consider a word like 'cat', which does genuinely seem to work representationally. The representationalist account has no problem explaining that 'cat' means what it does. It simply points out that 'cat' refers to the familiar small, furry, purring-and-meowing animals that many people have as pets.
However, how does this correlation of the word 'cat' to living, breathing cats take place, and why does this correlation work the way it does? With a visual representation, there's at least an obvious similarity between the representation and the thing represented that makes these how and why questions seem unproblematic. The visual representation literally represents the thing being represented, and if any sighted person doubts this connection, or how it works, or why it works, they can literally see for themselves. But with linguistic representations the string of three letters, C-A-T, has no such similarity to actual cats, and therefore cannot be said to literally represent cats in the same way. There's a reason why an English-speaking adult always needs to take a German class before she can understand that the sentence 'Die Katze ist auf der Matte' means that the cat is on the mat, and yet such a person has no need to take a similar class before understanding that a picture of a cat on a mat drawn by a German speaker shows that the cat is on the mat.
This points towards a drastic difference between linguistic and literal representations, a difference that has everything to do with how and why each works the way it does. Unfortunately, in identifying language with representations, this is precisely the difference that the representational account is--by design--not able to explain.
Now that we've heard a lot about what Brandom's answer is not, let's finally start outlining what his answer is.
To do so, let's first consider the troublesome word 'ouch'. Brandom would say that this word isn't used to represent anything (again, one doesn't "have time" for explicit representational thinking when one is in pain). Instead, it serves an expressive purpose to make one's inner pain accessible to the external world. It serves to make explicit what would otherwise be left implicit. In a way, 'ouch' is not a verbal representation of your pain--it is your pain, made verbal.
Perhaps surprisingly, Brandom argues that a similar story explains the meaning of the word 'if'. At base, the meaning of this word is to make explicit, to make public, and to make objective something which would otherwise be left implicit, private, and subjective. In short, its purpose is to express something; but what could this something be?
Brandom argues that this something is the flow of thinking itself. As thinking beings, we find ourselves having one thought, and then another, and then another. Also as thinking beings, we (usually) feel that our thoughts do not just appear arbitrarily to us. Instead, we sense that there is some rational order to them, some reason behind them. And how do we express this feeling of rational order? By using the word 'if' of course!
To express an individual thought, we just go ahead and assert it, but to express the reason tying thoughts together we use 'if' and other similar logical words. In a sense, if-statements just are our reasons, only made verbal.
To wrap up with Brandom's answer, let's turn to the unproblematically representational use of language illustrated by the third word we were talking about--'cat'. Brandom would concede that this and similar words have a representational function. However, what this means for Brandom is that we use these words to express certain representations that occur to us while we're thinking. So, on Brandom's account, representation just is a form of expression (a conclusion that should come as no surprise to any artists out there).
But how does this help us answer the properly philosophical how and why questions that the representational account got bogged down on? Brandom's answer has to do with the nature of the representations under consideration. We noted that visual representations have an obviousness to them. At a certain level, one doesn't have to take a class to learn how they work; one implicitly already knows.
Brandom's explanation for why this is is that visual representations have a physical basis that is obvious and non-arbitrary to anyone who has the practical experience of living in the physical world. Our implicit knowledge of the physical world is of course imperfect, hence why some of us dedicate so much of our time to developing physics as a discipline of explicit knowledge. But our implicit knowledge isn't nothing, and it's something we have thanks just the nature of visual representations and our relation to them.
Our problem with the representationalist account was that it doesn't point us to a similarly obvious and non-arbitrary basis for linguistic representations. In fact, it leaves us feeling like there might not be any such basis.
This is where Brandom comes to the rescue. In addition to finding ourselves in an external world, we humans find ourselves in a mental world. Brandom's key observation is that just as the external world is structured by physical laws, this mental world is structured by rational laws, and therefore offers a similarly obvious and non-arbitrary basis for understanding linguistic representations (at least to anyone with the practical experience of living in this rational world). This knowledge is of course implicit, but again some people have dedicated much time to making it explicit. Brandom is one such person, and he spends most of the 700+ pages of Making It Explicit to just this task.
The final upshot is that, as valuable as this explicit logical knowledge is, it's something we've always already known implicitly. And all thanks to the expressive nature of us as thinking beings!
To conclude, let's highlight four of Brandom's theses that go a long way to summarizing everything that we've said so far.
Brandom's rationalism should be what comes across most clearly of the four, insofar as this is what allows him to answer the how and why questions from above.
His pragmatism is perhaps less obvious, but no less important because of it. Note that it is only because we have the practical experience of living in two worlds that we have any implicit knowledge of representations, visual or rational. This is pragmatism in action.
The 'Fraught with Ought' thesis is the least developed of the four in what I've said above, largely because it begins to take us away from the philosophical broad brush strokes and into the logical weeds. For us, it is enough to note that physical laws are not fraught with ought, because they do stipulate what must happen. This indicates a massive difference between our relation to the physical, external world and the rational, internal world, which in turn explains the difference between physics and logic (the respective disciplines that study each world). However, this difference only makes a difference for the type of answer we give to the how and why questions, not whether there is an answer to give.
Finally, expressivism is the name for the view we get when we combine everything we've said so far. The important point to end with is that Brandom's expressivism is universal--it's meant to explain all language.