Philosophers have had a longstanding problem with rhetoric. The standard view of the quarrel is well-known: philosophy is a truth-directed activity concerned with reasoned argument, while rhetoric is uninterested in truth and concerned merely with persuasion. This view is often traced to Plato, but it is too crude. As Plato himself recognised, philosophers need to present their ideas in persuasive form if they are to gain acceptance, and there are uses of rhetoric that can further our commitment to truth rather than frustrate it. The power of an effective speaker to captivate an audience is apt to arouse our suspicion in democratic politics, yet we should also acknowledge that the practice of rhetoric can serve a civic purpose. The real question here is what distinguishes good rhetoric from bad rhetoric.

Plato was deeply interested in this question. Although a concern for truth pervades his thought, this is not the main or the most important problem he has with rhetoric in his dialogues. To understand Plato’s critique, we need to read it against the backdrop of a deep mistrust of persuasive speaking that he shared with his contemporaries following Athens’ loss of the Peloponnesian War against Sparta in the late fifth century BCE. Apart from the huge death toll and casualties suffered by the city, the loss had a monumental impact on the Athenian psyche. In the Laws, usually regarded as Plato’s last work, he has his Athenian Visitor state that ‘[E]very Greek takes it for granted that my city loves talk and does a great deal of it, whereas Sparta is a city of few words, and Crete practices cunning more than talk.’

No doubt there were many factors that contributed to Athens’ loss of the war, but if there is one thing we can point to above all, it is the fact that the Athenian people themselves were persuaded by charismatic statesmen and generals of the period to undertake a series of disastrous military campaigns. As many writers – historians, tragedians and comedians alike – would lament during and after the war, it was in large part the Athenians’ ‘love of talk’ that led to their defeat.

Athens’ downfall provides us with a cautionary tale in our own era. While it would be wrong to reject a persuasive speech simply because the speaker fails to belong to our preferred political party, it would be equally wrong to think that we should accept every speech that strikes us as persuasive. Adolf Hitler’s Nuremberg Rallies of the 1920s and ’30s were highly effective propaganda tools in consolidating power for the Nazi Party and influencing the views of the German people, but the wider effects of his ability to fabricate a redeemed Germany were devastating for the country. The principle here is simple: good rhetoric is not reducible to persuasive rhetoric. Persuasion might often be the goal of the rhetorician, but if rhetoric is to serve some civic good, it must serve the people on whom it operates. Plato was the first to observe that persuasion cannot in fact be the proper end of rhetoric, since it is an open question how it serves the interests of an audience to have their views influenced by a persuasive speech.

In his Gorgias and the Phaedrus, Plato therefore takes a different approach to the value of rhetoric. Together, these two works put forward a comprehensive theory of when and how a persuasive speech qualifies as good rhetoric. The Gorgias is best interpreted as a critique of the conventional practice of rhetoric. In this dialogue, Socrates argues that the chief purpose of conventional rhetoric is not (properly speaking) persuasion, but flattery. His point is that the practice of persuasive speaking typically achieves its effects by satisfying the pleasures and desires of an audience.

Notice that by moving here to the psychology of an audience, the rhetorician can now say something about how rhetoric serves the people on whom it operates. According to this view, the value of rhetoric lies in its ability to gratify and enlarge human appetites and impulses. Plato himself does not believe rhetoric functions best as a form of flattery, though he is correct that this is how the practice conventionally works. In addition to making direct appeals to people’s desires, a speaker can most effectively win acceptance for a particular policy or point of view by bolstering the entrenched beliefs of an audience and voicing their unspoken fears. Even if it is feigned, the reinforcement of these beliefs and fears can be thrilling for an audience.

Now, Plato knew well of the frenzy that such flattering rhetoric can provoke in others. Thrasymachus, for instance, while famous as Socrates’ main antagonist in the Republic, was historically one of the leading rhetoricians of his day. His ability to use speech to influence an audience was so remarkable that Socrates refers to him in the Phaedrus as ‘clever at inflaming the many and, once they are inflamed, at hushing them again with his words’ magic spell’.

So what is the problem with such flattery? Suppose a politician delivers an effective speech by gratifying the desires of his or her constituency. No one can deny the sense of empowerment we experience when our feelings are confirmed and validated in this way. Why should such a speech not qualify as good rhetoric? Plato’s answer focuses on the object the rhetorician seeks to affect: human psychology. His problem with conventional rhetoric is that, by adopting flattery as its end, it assumes an utterly impoverished conception of human motivation – namely, that all we are essentially are pleasure-seekers.

In examining the nature of rhetoric, what we are really concerned with is the nature of the human soul

Plato’s own account of human psychology is often misunderstood. On a common misreading, reason and passion are taken to be in conflict. In fact, as he stresses in the Phaedrus, the best life for a human being is one in which reason and the passions work together as a team. In this dialogue, Socrates turns his attention to how the practice of rhetoric might function productively as an art, but he also develops one of his most detailed portraits of the human soul in the Platonic corpus.

The pairing of themes is deliberate. For if the conventional use of rhetoric is no art because it assumes a poor view of human psychology, as Socrates claims in the Gorgias, then an artful use of rhetoric must operate on the basis of a good view of human psychology. In examining the nature of rhetoric, what we are really concerned with, according to Plato, is the nature of the human soul.

So what is the nature of the human soul? In the Phaedrus, Socrates defines the soul in general as a principle of self-motion in living things. He then proceeds, in his celebrated chariot allegory, to divide the human soul into different parts: a charioteer, representing the human intellect, trying to steer two horses, one of noble breed, the other wild (representing the rational and irrational passions). Plato does not deny our nature as pleasure-seekers in this allegory. But if we are to move ourselves as human beings, he believes it is crucial that we develop our nature as reason-seekers. Why exactly? His main answer in the Phaedrus is that the reason-seeking part of us represents the power each of us has as a human being to engage in independent thought: to understand and appreciate for ourselves a set of ideals and aspirations we wish to live by. Indeed, he depicts our desire to develop this understanding as a force so compelling that it is best classified under the category of erotic love.

Plato’s views on persuasive speech offer us a helpful set of tools in assessing the value of rhetoric in modern civic life. His critique explains, first of all, our tendency in democratic politics to respond suspiciously to the skills of a persuasive speaker. The problem here lies not in the use of persuasive speech as such, but in the aim of many effective rhetoricians to subvert or short-circuit an audience’s power of independent thought. In Mein Kampf (1925), Hitler is startlingly open about this aim in expounding his views about the correct use of propaganda: ‘The art of propaganda consists precisely in being able to awaken the imagination of the public through an appeal to their feelings, in finding the appropriate psychological form that will arrest the attention and appeal to the hearts of the national masses.’ This is fundamentally a form of what Plato terms flattering rhetoric.

In addition to explaining the nature of bad rhetoric, however, Plato’s critique also helps illuminate for us the nature of good rhetoric. If to have a soul is to be a self-moving thing, and what is essential to the self-motion of the human soul is our ability to think for ourselves, then an artful use of rhetoric should cultivate that ability in particular. When we encounter persuasive speakers of this sort in the political sphere, we should not respond cynically. Instead, we should welcome such encounters, because they are opportunities to have our desire to understand enlisted, at the same time as – and even through – our passions.

Is rhetoric of this sort possible in civic life today? We are inclined to believe that the end of all rhetoric is persuasion or conviction alone, and that such a goal is ill-suited to the promotion of independent thought in an audience. Yet this is a mistake. An artful rhetorician might need to strike a balance between these two goals, but they are not incompatible. The danger to be avoided always is the kind of rhetoric that carries the authority of conviction at the expense of an audience’s independent thought. There have been speeches in the modern era that have moved their listeners profoundly while retaining this basic respect for the sovereignty of the human soul.

Consider Abraham Lincoln’s Gettysburg Address (1863), regarded even today as a model of American oratory. In three compact paragraphs, the speech gives expression to a past, a present and a future United States. Lincoln delivered the speech on a formal occasion, at the dedication of a cemetery for those who fought and died at a key turning point in the American Civil War, but from the opening sentence he makes clear how he will use the moment to reflect on the theme of dedication more generally:

Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.

The rest of the speech deftly juxtaposes the dedication of the physical space in which the audience stands with the dedication of all Americans to this abstract proposition, expressed in the Declaration of Independence (1776): the ideal of liberty for all.

Can political rhetoric be highly persuasive and at the same time spur independent thought?

‘It is altogether fitting and proper,’ Lincoln affirms, to commemorate the dead, but in the pivot that gives the speech its rhetorical force, he states that ‘in a larger sense, we can not dedicate – we can not consecrate – we can not hallow – this ground.’ Those who fought on the battlefield had already accomplished that. For those looking to the future, for the living, Lincoln asks instead that they rededicate themselves to the cause of human equality and freedom:

It is for us the living, rather, to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us – that from these honoured dead we take increased devotion to that cause for which they gave the last full measure of devotion – that we here highly resolve that these dead shall not have died in vain – that this nation, under God, shall have a new birth of freedom – and that government of the people, by the people, for the people, shall not perish from the earth.

The great power of the Gettysburg Address, full as it is with feeling and urgency, comes from its invitation to the listener to consider the basis on which the US was founded. The persuasiveness of the speech consists not just in its ability to stir the passions of an audience and instil conviction, but also in its ability to get ordinary Americans to think more conscientiously than they had previously about the coherence of their own ideals and the application of those ideals in practice. The audience is moved, but also (in Plato’s sense) self-moved, to the extent that they are led to think for themselves.

If this is right, we can see why the assumption that rhetoric serves as a pale substitute for reason and argument is too simplistic. Good rhetoric also does the work of reason, though in a different form than philosophical argument. Plato came to be pessimistic about the rhetoric of his contemporaries in democratic Athens, which might be why he set up his Academy as a place where the practice of independent thinking could flourish. Yet there have been moments in history since then that should leave us more hopeful about the prospects for good rhetoric – or at least less doubtful. The important question for us today is: ‘Can we conceive of a piece of political rhetoric that is both highly persuasive and at the same time spurs independent thought?’ That is not a rhetorical question. If we can’t, we might be in trouble.