Plato and Aristotle are usually understood to have completely contrasting philosophical approaches.  Although Plato was Aristotle’s teacher at the Academy in Athens, Aristotle rejected Plato’s focus on metaphysics and reason, choosing instead to explore the limits of Physics and observation.  Clearly, Aristotle’s philosophical approach has more influence today.  While modern science has moved way beyond some of the theories which Aristotle proposed on the basis of observation – such as that the universe is infinite, that birds turn into fish and that men implant a “homonucleid” in a woman’s womb – scientific method still accepts Aristotle’s claim that knowledge must begin with observation and that reason must not stray too far from what can be observed, into the realm of speculation.  Nevertheless, and despite the continued popularity of the naïve materialism that emerged out of Aristotle’s philosophical approach, relatively recent developments in philosophy and science have shown that it is Plato’s philosophical approach which is more compelling.

Aristotle’s philosophical approach was supported by Locke, Hume, Kant & Ayer.  All of these philosophers dismissed Plato’s claim that human beings are born with innate ideas which we “remember” through rational reflection.  Instead, like Aristotle, John Locke argued that human beings are born as tabula rasa – blank slates – and that all our knowledge comes from sense-experience, as processed and interpreted by reason.  Hume essentially agreed, as did Kant – who also limited possible knowledge-claims to the synthetic and the analytic – and later Hume’s biographer AJ Ayer in the 20^th Century.  The very idea that human beings could source new knowledge in rational reflection without relying on sense-experience seemed to open the door for unsupported speculation, the opposite of knowledge and probably a barrier to attaining it.  Nevertheless, despite the common-sense appeal of empiricism, it has come under attack from several directions.  Firstly, the idea that the only meaningful knowledge-claims are those which can be verified through sense-experience (or are tautologies) was shown to be narrow and impractical.  Aristotle’s attempt to build out from sense-experience to demonstrate the necessary existence of a Prime Mover and a common human telos in which to ground a universal, absolute system of moral philosophy was widely criticised during the Enlightenment and then into the 20^th Century.  Descartes and Berkeley pointed out the problems with relying on sense-experience at all.  The way I see things is not necessarily the way that they are; the senses are limited and frequently faulty. Further, there is no way to prove that the exterior world is real, not a dream-world and permanent; as Descartes pointed out, the only thing that I can know with certainty is cogito ergo sum. David Hume himself pointed out additional assumptions on which Aristotle’s reasoning rests, that our limited observations support universal claims about natural laws and that the impression of order and teleology is not just that, an impression.  Cartesian scepticism, Berkeley’s idealism and even Hume’s epistemology point to the shortcomings of Aristotle’s philosophical approach and Descartes and Berkeley’s arguments at least lend support to Platonic rationalism.

Secondly and despite the “liberalisation of empiricism” to include discussions of topics like history that are only weakly verifiable, the focus on sense-experience as the only source of new knowledge excludes important areas of human discussion – and experience – such as religion and morality.  Further, as erstwhile Logical Positivist Karl Popper pointed out, modern science cannot function under a verificationist approach to knowledge.  For example, quantum particles are changed by the act of observing them, demonstrating that the senses do not offer the transparent window on external reality that Aristotle or later empiricists and positivists claimed. Also, as GE Moore pointed out, there is no way to prove that “this is a hand”… at some point the attempt to describe and communicate about sense-experience relies on concepts and conventions, as Hume previously acknowledged when he pointed out that properties like colour are secondary, not primary qualities and this depend on the way we see things, not the way they really are.  It is true that Popper’s falsificationism does not stray too far from that which can at least in principle be experienced through the senses… and certainly does not seem to offer much support to Plato’s rationalism… but it allows for beliefs to be accepted as knowledge providing that criteria for their falsification are accepted.  In the scientific sense, falsification allows for scientists to speculate about the origins and fundamental nature of the universe and about multiverses – none of which can ever be directly observed – if they define the circumstances under which they would modify or abandon their theories.  In a broader sense, falsification enables people to propose moral laws meaningfully – laws which could never be seen, heard, touched, smelled or tasted – providing that they would be willing to accept falsifying evidence.  Alternative theories of knowledge, such as Quine’s holism, recognise the need to include all of human experience rather than just to focus on sense-experience, seeing mathematics as close to the centre of the “web of human experience”, and as such show that Aristotle’s narrower approach has been superseded.  The general rejection of the Verification Principle and the move to find other approaches to knowledge and meaning in the mid-20^th century points to the fact that relying on the empirical senses as the source of all new human knowledge – as Aristotle and the empiricists did – is limiting and leads to an impoverished world-view.

Today, Plato’s is a more convincing as an approach to Philosophy than Aristotle’s, because he recognised that reason offers people a better means of understanding things as they really are… although he probably was too confident about how far this could go.  As Descartes pointed out in the 17^th Century, reality goes much deeper than superficial appearances.  This begins with all the assumptions people made for millennia – that the earth is flat, the centre of the universe, orbited by the sun and stars in fixed orbits – and includes assumptions that even scientists still make every day – that matter is real, that the way we see things is the way they are, that this part of the universe is a fair sample of a homogenous whole.  To the sceptic, everything in the world of appearances is open to question and nothing is known for certain.  Nevertheless, starting with the foundational claim that I exist as a thinking being, we can have certain a priori knowledge of mathematics, which does more to explain the reality of the universe than ever can direct observations, as theoretical physicists will confirm.  This shows that Plato’s rationalism is more compelling, because it supports current thinking in Mathematics, Theoretical Physics, Particle Science and Cosmology.

In addition, seeing thought and reason as primary also makes more sense of the broader experience of being human.  Plato’s dualism, his suggestion that soul/mind and physical body are separate and even separable, remains far more popular than Aristotle’s suggestion that the soul and body are one and inseparable.  Despite Aquinas’ attempt to argue that an Aristotelian “soul” could be transferred to a new “heavenly” body in an afterlife, this raises more questions than it solves.  The belief in the afterlife, a belief which is extremely widespread, consistent and persistent and even, as Kant argued, required to explain the freedom we all experience as human beings, is much better supported by Platonic dualism than by Aristotlelian monism.  Most people experience a continuity of personal identity and sense of self from early childhood to death.  If the soul is the “formal cause of the body” and the body changes radically over time then we might expect the soul to change as well… but it is consistent.  Most people would agree that changes to the body – becoming a paraplegic for example – has little or no effect on the soul or sense of self, which we might expect to alter if the soul was just the formal cause of the body as Aristotle proposed.  Clearly, if Aristotle was here to defend himself he might point to the effects of traumatic brain injury or dementia, suggesting personal identity depends on the brain as a physical organ and is in no way separate or separable.  As Gilbert Ryle said, Plato’s talk of souls could rest on a category mistake; the soul could be no more than a “ghost in the machine”.  And yet, to dismiss all the evidence for out-of-body and near-death experiences just because it cannot be empirically verified would be hasty.  Recent medical studies by Dr Sam Parnia (AWARE and AWARE II) suggest that the evidence better supports the brain mediating rather than generating the mind.  To use Plato’s own allegory of the cave, might dismissing reports of a metaphysical reality and attacking those who make them be rather like the prisoners in the cave threatening the one who escaped and returned?  Are we satisfied to stay chained in the shadows, blocking out any evidence that could expand our world-view, or are we brave enough to contemplate the possibility of a bigger reality beyond? Plato’s dualism is more persuasive than Aristotelian materialism, because it accounts both for the experience of being human and research into Out of Body and Near Death Experiences.

Further, Plato’s world-view makes more sense of the human experience of morality than does Aristotle’s.  Both GE Moore in his “Principia Ethica” (1903) and later Iris Murdoch in her “Sovereignity of the Good” (1970) pointed out that we recognise goodness when it cannot be reduced to what is useful or makes people happy.  Not to be distracted by Plato’s language in relation to the forms, it is fair to say that there is an ideal of goodness which people experience as a rational intuition.  Kant described this in terms of the moral law, which appeals directly to reason as a synthetic a priori and shows all thinking people their duty to act transparently, on principle and with non-preferential humanitarian love.  Modern proponents of Natural Law like John Finnis explain what Aquinas called conscientia, the inbuilt desire to follow the direction of synderesis or what Aristotle called phronesis, in these terms.  It is difficult to explain why the way people do behave is the way they ought to behave without appealing to reason, to the sort of rational intuitions which Plato sought to explain.  The existence of a “form of the good”, howsoever this is described, explains the existence of the universal human virtues which CS Lewis and Alastair MacIntyre described and the absolute authority of agape-love which Joseph Fletcher appealed to.  Iris Murdoch developed her own version of Platonism in which she also proposed that human beings share rational intuitions of “forms” such as goodness and beauty.  This, she argued, explains why human beings seem to share the same ideas of what is good and beautiful, despite cultural and/or historical distance between them.  CS Lewis made a similar point in his “Mere Christianity” (1953), pointing out that ideas of justice exist in a similar way across time and the world.  This suggests that Plato’s philosophical approach makes more sense of human experience than scientific materialism, based on Aristotle’s philosophical approach, which tries to reduce morality and aesthetics to utilitarianism or evolutionary advantage.

Finally, the existence of innate ideas explains human language acquisition more convincingly than any other hypothesis.  As Noam Chomsky argues, human beings seem hard-wired for language, sharing a common conceptual and grammatical framework which needs only to be expressed through the conventions of a particular language.  Infants acquire language much more quickly than we might expect and non-human species (like chimps, dolphins and parrots) face an insuperable obstacle to using language rather than just naming things.  That no animal can talk is about much more than their lack of verbal dexterity, it is about their lack of the necessary neurological structures.  As Wittgenstein remarked in a different context, if a lion could talk we could not understand him.  Nativist theories of language acquisition like that of Chomsky would say that this is because the lion’s language would employ a whole other conceptual and grammatical framework as well as because the lion’s form of life is necessarily alien.  This shows that Plato’s philosophical approach, and particularly his belief in innate ideas, accounts for the evidence concerning human language acquisition better than Aristotelian materialism has.

In conclusion, despite the continued popularity of Aristotle’s philosophical approach, recent developments in both science and philosophy suggest that it is Plato’s approach which holds more interest going forward into the 21^st century and beyond.