The simplest notion of reference is a kind of literal or metaphorical pointing at things. This serves as a kind of indispensable shorthand in ordinary life, but the simplicity of metaphorical pointing is illusory. It tends to tacitly presuppose that we already know what it is that is being pointed at.
More complex kinds of reference involve the idea of representation. This is another notion that is indispensable in ordinary life.
Plato and Aristotle used notions of representation informally, but gave them no privileged status or special role with respect to knowledge. They were much more inclined to view knowledge, truth, and wisdom in terms of what is reasonable. Plato tended to view representation negatively as an inferior copy of something. (See Platonic Truth; Aristotelian Dialectic; Aristotelian Semantics.)
It was the Stoics who first gave representation a key role in the theory of knowledge. The Stoics coupled a physical account of the transmission of images — bridging optics and physiology — with very strong claims of realism, certain knowledge both sensory and rational, and completeness of their system of knowledge. In my view, the Stoic theory of representation is the classic version of the “correspondence” theory of truth. The correspondence theory treats truth as a simple “correspondence” to some reality that is supposed to be known beyond question. (Such a view is sometimes misattributed to Plato and Aristotle, but was actually quite alien to their way of thinking.)
In the Latin middle ages, Aquinas developed a notion of “perfect” representation, and Duns Scotus claimed that the most general criterion of being was representability. In the 17th century, Descartes and Locke built foundationalist theories of certain knowledge in which explicitly mental representations played the central role. Descartes also explicitly treated representation in terms of mathematical isomorphism, representing geometry with algebra.
Taking putatively realistic representational reference for granted is a prime example of what Kant called dogmatism. Kant suggested that rather than claiming certainty, we should take responsibility for our claims. From the time of Kant and Hegel, a multitude of philosophers have sharply criticized claims for certain foundations of representational truth.
In the 20th century, the sophisticated relational mathematics of model theory gave representation renewed prestige. Model-theoretic semantics, which explains meaning in terms of representation understood as relational reference, continues to dominate work in semantics today, though other approaches are also used, especially in the theory of programming languages. Model-theoretic semantics is said to be an extensional rather than intensional theory of meaning. (An extensional, enumerative emphasis tends to accompany an emphasis on representation. Plato, Aristotle, Kant, and Hegel on the other hand approached meaning in a mainly intensional way, in terms of concepts and reasons.)
Philosophical criticism of representationalist theories of knowledge also continued in the 20th century. Husserl’s phenomenological method involved suspending assumptions about reference. Wittgenstein criticized the notion of meaning as a picture. All the existentialists, structuralists, and their heirs rejected Cartesian/Lockean representationalism.
Near the end of the 20th century, Robert Brandom showed that it is possible to account very comprehensively for the various dimensions of reference and representation in terms of intensionally grounded, discursive material inference and normative doing, later wrapping this in an interpretation of Hegel’s ethical and genealogical theory of mutual recognition. This is not just yet another critique of representationalism, but an actual constructive account of an alternative, meticulously developed, that can explain how effects of reference and representation are constituted through engagement in normative discursive practices — how reference and representation have the kind of grip on us that they do, while actually being results of complex normative synthesis rather than simple primitives. (See also Normative Force.)