As the campaign for the White House gears up and the struggle over Brexit becomes ever more intense, we’re inundated with spin, fake news and alternative facts. Techniques of persuasion – which the ancient Greeks called the science of rhetoric – are very much alive.

Homer’s Iliad (8th century BC) opens with the dispute between Agamemnon and Achilles pitching inherited power against proven merit. But systematic studies of rhetoric, and realisations that it empowered immoral people, then emerged with 5th-century democracies. Barry Unsworth’s 2002 novel The Songs of the Kings retold the Iliad and Euripides’ Iphigenia in Aulis to skewer the sophisticated spin of New Labour, especially Peter Mandelson. Agamemnon’s chief strategist is Odysseus, whose “own fluency betrayed him sometimes, when he felt the excitement of the prospect, through words alone, of prevailing over another mind, using the fears and desires of that mind to disarm and control it”.

Plato concluded that rhetoric dangerously prioritised influencing opinion over the pursuit of truth. But his pragmatic student Aristotle opened his Rhetoric with a refutation: we all need to persuade others of our views and understand techniques of debate to analyse the claims made by would- be leaders. Rhetoric has no immanent morality. It can be used for good as well as evil.

The best book on the debate between Plato and the orators, and its post-Renaissance continuation, is Brian Vickers’s In Defence of Rhetoric, with its useful appendix describing the rhetorical figures identified in antiquity and still in constant use today (anaphora, metonymy and so on).

The instrumentality of ancient speechmaking in the political oratory of more recent times is also explored in Gary Wills’s Lincoln at Gettysburg: The Words that Remade America. Wills examines the inspiration behind Abraham Lincoln’s 1863 address at the Soldiers’ National Cemetery in Pennsylvania – Pericles’ oration at the funeral of the Athenian war dead of 431BC, recorded by Thucydides. Pericles rousingly concluded, “Such is the city for whose sake these men nobly fought and died; they could not bear the thought that she might be taken from them; and every one of us who survive should gladly toil on her behalf.” Lincoln praised not the dead but the principles on which their country was founded.

Angela Davis, pictured in 1970. Photograph: AP

Wills argues that his speech was revolutionary in assuming that the Declaration of Independence, not the Constitution, was the supreme articulation of American government. He proposed that the US is a single nation and a single people, rather than an association of separate states. Lincoln follows Pericles in grasping a historic opportunity to frame a vision of his whole community and its values. He also followed the classical structure of Pericles’ oration in discussing first the dead and secondly the living – survivors, the bereaved – and instructing them on their future.

Rather more cynical political rhetoric is exposed in the context of colonial Nigeria in Chinua Achebe’s Things Fall Apart. It is contrasted with the self-expression of Okonkwo, the Igbo protagonist. Achebe conveys the collision of the different thought systems of colonisers and colonised through deliberation in both direct and indirect discourse, while heightening the deceptively neutral narrator’s eloquence with imagery, rhythms, rhetorical figures and wordplay.

A speaker who is anything but neutral is the civil rights activist Angela Davis. Her collection The Meaning of Freedom, and Other Difficult Dialogues gathers 12 previously unpublished speeches, delivered between 1994 and 2009, which expose the beating heart of the racist carceral state, global neoliberalism, and patriarchy’s symbiosis with capitalism. This is rhetoric at its compelling best, because skill is allied with moral conviction. Unlike many politicians, Davis’s authenticity shines through every phrase.