Metaphors expand the capacity of language by enabling the conveyance of complex, abstract, or nuanced ideas through more familiar terms. They work by transferring meaning from one domain to another, allowing for creative expression and thought. For example, when we say "time is a thief," time is not literally stealing anything, but the metaphor vividly conveys the concept of time passing quickly and irretrievably. Metaphors often express ideas that cannot be as effectively conveyed through literal language, providing depth and emotion to our communications. They also play a cognitive role, influencing the way we think and perceive the world by framing our experiences in novel ways.

The philosophy of language intersects with ethics in several ways, particularly in the analysis of how language is used in communication. The ethics of language considers issues like the intent and consequences of speech acts, the responsibility of truth-telling, and the impact of language on perpetuating or challenging social inequalities. It also examines the ethical implications of persuasive language, such as propaganda or advertising, and the moral obligations of speakers and listeners in maintaining honest and respectful discourse. Additionally, the use of derogatory language and hate speech presents ethical concerns about the harms language can cause, raising questions about freedom of speech and its limits. Thus, the philosophy of language engages with ethical considerations around the power of language to influence thought, action, and social structures.

Indexical expressions, such as "I," "here," and "now," possess meanings that are inherently context-dependent and can only be fully understood relative to a particular situation or speaker. This challenges the idea that words have stable, context-independent meanings, which is a cornerstone of traditional semantic theories. For example, "I" refers to the person speaking, which changes with each use, making it impossible to assign a fixed referent to the term. Such expressions show that some parts of language are dynamic and variable, reflecting the fluid nature of meaning and its contingent relationship with the surrounding context.

Performativity, a concept introduced by philosopher J.L. Austin, challenges the traditional notion that language's primary function is to describe the world and convey information. Instead, it suggests that language can enact or perform actions. For instance, when a couple says, "I do" in a wedding ceremony, they are not just stating a fact but actually performing the action of getting married. Similarly, uttering "I name this ship the Queen Elizabeth" while smashing a bottle against the ship’s hull is part of the act of naming. This indicates that the role of language goes beyond mere description; it is an active participant in shaping reality, rather than a passive vehicle for conveying pre-existing ideas.

Semantic externalism is a theory that argues the meanings of words and the contents of thoughts are not determined solely by the individual's internal state but also by external factors such as the environment and society. This theory, principally associated with philosophers like Hilary Putnam and Tyler Burge, posits that to know the meaning of a term like "water," one must consider its chemical composition (H2O), which is an external, empirical fact. In epistemology, this suggests that an individual's knowledge is not completely self-contained and that understanding and knowledge involve a relation with the external world. It shifts focus from a purely mentalistic perspective of meaning to one that recognises the significance of the external environment in shaping meaning and knowledge.