Plato (~428 BCE—348 BCE) is commonly considered to be one of the most influential writers in the history of philosophy.

Along with his teacher, Socrates, and student, Aristotle, Plato is among the most famous names in Western philosophy – and for good reason. He is one of the only ancient philosophers whose entire body of work has passed through history in-tact over the last 2,400 years, which has influenced an incredibly wide array of fields including ethics, epistemology, politics and mathematics. 

Plato was a citizen of Athens with high status, born to an influential, aristocratic family. This led him to be well-educated in several fields – though he was also a wrestler! 

Influences and writing

Plato was hugely influenced by his teacher, Socrates. Luckily, too, because a large portion of what we know about Socrates comes from Plato’s writings. In fact, Plato dedicated an entire text, The Apology of Socrates, to giving a defense of Socrates during his trial and execution.  

The vast majority of Plato’s work is written in the form of a dialogue – a running exchange between a few (often just two) people.  

Socrates is frequently the main speaker in these dialogues, where he uses consistent questioning to tease out thoughts, reasons and lessons from his “interlocutors”. You might have heard this referred to as the “Socratic method”.  

This method of dialogue where one person develops a conversation with another through questioning is also referred to as dialectical. This sort of dialogue is supposed to be a way to criticise someone’s reasoning by forcing them to reflect on their assumptions or implicit arguments. It’s also argued to be a method of intuition and sometimes simply to cause puzzlement in the reader because it’s unclear whether some questions are asked with a sense of irony. 

Plato’s revolutionary ideas span many fields. In epistemology, he contrasts knowledge (episteme) with opinion (doxa). Interestingly, he says that knowledge is a matter of recollection rather than discovery. He is also said to be the first person to suggest a definition of knowledge as “justified true belief”.  

Plato was also very vocal about politics, though many of his thoughts are difficult to attribute to him given the third person dialogue form of his writings. Regardless, he seems to have had very impactful perspectives on the importance of philosophy in politics: 

“Until philosophers rule as kings or those who are now called kings and leading men genuinely and adequately philosophize, that is, until political power and philosophy entirely coincide, while the many natures who at present pursue either one exclusively are forcibly prevented from doing so, cities will have no rest from evils, … nor, I think, will the human race.” 

Allegories

You might have also heard of The Allegory of the Cave. Plato reflected on the idea that most people aren’t interested in lengthy philosophical discourse and are more drawn to storytelling. The Allegory of the Cave is one of several stories that Plato created with the intent to impart moral or political questions or lessons to the reader.  

The Ring of Gyges is another story of Plato’s that revolves around a ring with the ability to make the wearer invisible. A character in the Republic proposes this idea and uses it to discuss the ethical consequences of the item – namely, whether the wearer would be happy to commit injustices with the anonymity of the ring.  

This kind of ethical dilemma mirrors contemporary debates about superpowers or anonymity on the internet. If we aren’t able to be held accountable, and we know it, how is that likely to change our feelings about right and wrong? 

The Academy

The Academy was the first institution of higher learning in the Western world. It was founded by Plato some time after he turned 30, after inheriting the property. It was free and open to the public, at least during Plato’s time, and study there consisted of conversations and problems posed by Plato and other senior members, as well as the occasional lecture. The Academy is famously where Aristotle was educated.  

After Plato’s death, the Academy continued to be led by various philosophers until it was destroyed in 86 BC during the First Mithridatic War. However, Platonism (the philosophy of Plato) continued to be taught and revived in various ways and has had a lasting impact on many areas of life continuing today.  

Immanuel Kant (1724—1804) was a transformative figure in modern Western philosophy due to his ground-breaking work in metaphysics and ethics.

He was one of the most influential philosophers of the 18th century, and his work in metaphysics and ethics have had a lasting impact to this day.

One of Kant’s greatest contributions to philosophy was his moral theory, deontology, which judges actions according to whether they adhere to a valid rule rather than the outcome of the action.

According to Kant’s theory, if you follow a valid moral rule, like “do not lie”, and it ends up with people getting harmed, then you’ve still done the right thing.

Deontology has since become one of the “big three” moral frameworks in the Western tradition, along with virtue ethics (based on Aristotle’s work) and consequentialism (exemplified by utilitarianism).

The will

Kant argued that morality cannot be based on our emotions or experience of the world, because this would leave it weak and subjective, and lacking the unconditional obligation that he believed was central to moral law.

“Every one must admit that a law has to carry with it absolute necessity if it is to be valid morally – valid, that is, as a ground of obligation,” he wrote.

His concern was that without this sense of unconditional obligation, a moral rule like ‘do not lie’ could compete with and be overridden by other concerns, like someone deciding they could lie because it suits their interests to do so, and they value their interests more than morality.

Rather, Kant argued that morality must be based on reason, which alone can provide the unconditional necessity that makes morality override our subjective interests.

Kant’s starting point was with our very nature, as inherently rational beings with ‘free will.’ He argued that it was this will that sets us apart as ’persons’ rather than ’things’  in the world, which are at the mercy of causal forces.

Our will gives us the ability to not only decide how to achieve our ends, but also about which ends to pursue; that’s just what freedom means. However, Kant argued that when we understand our nature as rational beings, we will understand that reason commands us to behave in a certain way, and this could form the basis of objective moral law.

The Categorical Imperative

Kant drew a famous distinction between different types of commands, or imperatives, which direct us how to act. One type are hypothetical imperatives.

So, one hypothetical imperative might say if you want to get to the 5:05 PM bus on time, then you must leave home no later than 5 p.m. Many moral systems of his time were effectively based on hypothetical imperatives, with the ends being things like achieving happiness or satisfying our interests.

However, Kant believed that such hypothetical imperatives could not be the basis of morality, as morality must bind us to act unconditionally and irrespective of any other ends we might have. Hence, someone who followed hypothetical imperatives in order to achieve ends like satisfying their desires or to avoid punishment was not acting morally.

He contrasted these with categorical imperatives do bind us unconditionally, no matter what other ends we might have. Kant argued that morality must be made up of categorical imperatives, as these are the only rules that can give morality its unconditional necessity.

“If duty is a concept which is to have meaning and real legislative authority for our actions, this can be expressed only in categorical imperatives and by no means in hypothetical ones,” he wrote.

The question becomes: where do categorical imperatives come from? Kant argued that there is really only one categorical imperative, and it is derived from our very nature as rational agents.

Once we abstract away all the contingent circumstances and subjective desires that people have, all we’re left with is our rational nature, which is something shared by all persons with a will. This objective point of view, stripped of all subjectivity, treats all rational agents equally, thus any imperative that directs them must apply universally.

From this Kant arrived at the categorical imperative, which is usually stated as “act only according to a maxim by which you can at the same time will that it shall become a general law”. This made all moral commands universal, so if something was wrong for me, then it must be wrong for all rational beings at all times.

This categorical imperative became the basis of all of Kant’s moral laws, effectively enshrining a particularly rarefied version of the Golden Rule.

Kingdom of Ends

Because we are inherently rational agents, we are both the authors and the subjects of the moral law. As such, Kant said that every person – indeed, every rational being – is an “end in himself, not merely as a means for arbitrary use by this or that will”.

This means we must treat all rational beings as ends in themselves and not just as means to achieve whatever ends we might have.

So, Kant argued, if every rational agent were to obey the categorical imperative, and treat everyone else as ends and not means, then it would lead to what he called the “kingdom of ends.”

It’s a kingdom in the sense that it’s a union of individuals who are all acting under a common law, and in this case the law is the categorical imperative, which urges everyone to treat everyone else as an end in themselves.

Kant admitted that this would be something of a moral utopia, but he put it forward as a vision for what a truly rational moral society might look like.

Controversy and Influence

Kant’s deontological ethics has been hugely influential but also controversial, being criticised by many philosophers as being based on an unrealistic conception of human rationality as well as being overly inflexible.

For example, Kant argued that it was always wrong to lie, because if one were to lie it would effectively endorse lying for everyone, and this would violate people’s rational autonomy.

However, we can imagine some situations where lying might be considered to be the right thing to do, such as lying to a prospective murderer in order to conceal their potential victims. Not to mention lying to one’s partner about their sartorial choices in order to maintain a harmonious domestic environment.

This is why many ethical consequentialists, who believe that it’s outcomes that really matter, have been known to gnash their teeth at the prospect that Kant demands we never lie.

Some thinkers have also – perhaps uncharitably – said that Kant effectively remade a kind of divine command theory of morality, which was popular in his Lutheran Christian community, except he replaced God with Reason (and even then, snuck a bit of God in on the side).

Kant’s philosophy has proven to be tremendously influential. His synthesis of empiricism and rationalism proved to be a breakthrough at the time, and his moral theory still has ardent defenders to this day.

There’s no question that philosophy is littered with the workings of male minds. What’s less known are the many brilliant women whose contributions throughout history have shaped our world today. Here are seven female philosophers to celebrate this International Women’s Day.  

Mary Wollstonecraft 

Mary Wollstonecraft (1759-1797) was a writer, philosopher and social activist. Wollstonecraft’s manifesto is 225+ years old, but far from obsolete. She passionately articulated for women to have equal rights to men in  A Vindication of the Rights of Woman in 1792, a century before the term feminism was coined. In a social system where women were “kept in ignorance” by the socioeconomic necessity of marriage and a lack of formal education, Wollstonecraft advocated for a free national schooling system where girls and boys would be taught together. The word patriarchy was not available to Wollstonecraft, yet she argued men were invested in maintaining a society where they held power and excluded women. 

“My own sex, I hope, will excuse me, if I treat them like rational creatures, instead of flattering their fascinating graces, and viewing them as if they were in a state of perpetual childhood, unable to stand alone.”

bell hooks

An outspoken professor, author, activist and cultural critic, bell hooks (1952 – 2021) work explores the connections between race, gender, and class. “Ain’t I A Woman” laid the groundwork for hooks progressive feminist theory, linking historical evidence of the sexism endured by black female slaves to its long-standing legacy on black women today. Born Gloria Watkins, hooks adopted her pen name after her late grandmother, wanting it written in lower case to shift the attention from her identity to her ideas. Now 38 years on from its original publication, her work remains radically relevant to the world today. 

“A devaluation of black womanhood occurred as a result of the sexual exploitation of black women during slavery that has not altered in the course of hundreds of years.”

Simone De Beauvoir

Simone de Beauvoir (1908-1986) was a French author, feminist and existential philosopher. She lived an unconventional life as a working experiment of her ideas. As an existentialist, de Beauvoir believed in living authentically and argued that people must choose for themselves who they want to be and how they want to live. The more pressure society – and other people – place on you, the harder it is to make that authentic choice, particularly for women. In her best-known work, ‘The Second Sex’ she famously posed that women are not born, they are made. Meaning that there is no essential definition of womanhood, rather social norms work hard to force them into a notion of femininity

“Man is defined as a human being and woman as a female – whenever she behaves as a human being she is said to imitate the male.”

Shulamith Firestone

Shulamith Firestone (1945-2012) was a writer, artist, and feminist whose book, The Dialectic of Sex, argued the structure of the biological family was primarily to blame for the oppression of women. Firestone proposed that over the course of human history, society itself had come to mirror the structure of the biological family and was the source from which all other inequalities developed. With a radical and uncompromising vision, she advocated for the development of reproductive technologies that would free women from the responsibilities of childrearing, dismantle the hierarchy of family life and set the foundations for a truly egalitarian society.  

“the end goal of feminist revolution must be… not just the elimination of male privilege, but of the sex distinction itself.”

Hannah Arendt

Johannah “Hannah” Arendt (1906 – 1975) was a German Jewish political philosopher who left life under the Nazi regime for nearby European countries before settling in the United States. Informed by the two world wars she lived through, her reflections on totalitarianism, evil, and labour have been influential for decades. Arendt’s most well-known idea is “the banality of evil”, explored in 1963 in a piece for The New Yorker that covered the trial of a Nazi bureaucrat, Adolf Eichmann. Following the election of Donald Trump, sales of Arendt’s book The Origins of Totalitarianism, already one of the most important works of the 20th century, increased by 1600%. 

“The sad truth is that most evil is done by people who never make up their minds to be good or evil.”

Martha Nussbaum  

Martha Nussbaum (1947-present) is one of the world’s most influential living moral philosophers, trailblazing in her philosophical advocacy for religious tolerance, feminism and the merits of emotions. Nussbaum believes the ethical life is about vulnerability and embracing uncertainty. She famously argued for the place of emotions within politics, saying democracy simply doesn’t work without love and compassion. In ‘Not for Profit: Why Democracy Needs the Humanities’ Nussbaum took on the education system, proposing that its role is not to produce an economically productive and useful citizen, but people who are imaginative, emotionally intelligent and compassionate. 

“To be a good human being is to have a kind of openness to the world, an ability to trust uncertain things beyond your own control.”

Simone Weil

Simone Weil (1909–1943) was a Philosopher, Christian mystic and political activist in the French Resistance, who TS Eliot called a “genius akin to that of the saints”. Weil gave attention to working conditions and is known to have given up a life of privileged to work in factories. This experience shaped her writings, which consider the relationship between individual and state, the nature of knowledge, the spiritual shortcomings of industrialism and suffering as key to the human condition. In The Need for Roots, Weil argued that society suffered an ‘uprootedness’, a deep malaise in the human condition due to a lack of connectedness to past, land, community and spirituality.  

“To be rooted is perhaps the most important and least recognized need of the human soul.”