Philosophy 100 Essential Thinkers

by Philip Stokes

Five Ways,

change. We can clearly see that some things in the world are in the process of change, and this change must be a result of something else, since a thing cannot change of itself. But the cause of the change itself, since in the process of change, must also be caused to change by something other than itself, and so on again, ad infinitum. Clearly, there must be something which is the cause of all change, but which itself does not undergo change. For, as Aquinas says,...

In the second Way, arguing in a similar manner to the first, Aquinas notes that causes always operate in series, but there must be a first cause of the se...

In the third Way, it is noted that we observe that things in the world come to be and pass away. But clearly not everything can be like this, for then there would have been a time when nothing existed. But if that were true then nothing could ever have come into being, since something cannot come from nothing. Therefore something must have always existed, and this is what people understand by God. The first, second and third Ways of Aquinas’ arguments are often called variations of a more general argument, the Cosmological Argument.

In the fourth Way, Aquinas offers a version of the Ontological Argument (see Anselm). In Aquinas’ version some things are noted to exhibit varying degrees of a quality. A thing may be more or less hot, more or less good, more or less noble. Such varying degrees of quality are caused by something that contains the most or perfect amount of that quality. Because, just as the sun is the hottest thing, and thus is the cause of all other things being hot, so there must be some fully ‘good’ thing which makes all other things good. That which is most good is, of course, God.

Finally, in the fifth Way, Aquinas relies on Aristotle’s notion of ‘telos’ or purpose. All things aim towards some ultimate goal or end. But to be guided by a purpose or a goal implies some mind that directs or intends that purpose. That director is, once again, God. Versions of Aquinas’ cosmological and ontological arguments are still accepted by the Catholic Chur...

Duns Scotus maintained that there are, with the help of divine illumination, but three modes of knowing that do not require further proof. First, there are principles known by themselves; following Cicero’s vocabulary, these would be called a priori. Second, there are things known immediately from experience and third, there is knowledge of our own actions.

According to Duns Scotus, that which individuates one thing from another depends on form rather than on matter.

Duns Scotus’ answer was that what individuates one thing from another is not its place in space and time, since we cannot clearly identify what the ‘it’ is over and above the exhibition of certain qualities, but rather the particular combination of qualities exhibited. In other words, the form of the thing itself.

‘Occam’s Razor’

The principle now famously known as ‘Occam’s Razor’ is a methodological principle concerning ontology. ‘Entia non sunt multiplicanda praeter necessitatem’ translates from the Latin as ‘Entities are not to be multiplied beyond necessity’. The principle reflects the idea that given two theories that equally explain the data, one should choose that theory which posits the minimum number of entities.

Occam held that universals only exist as part of human understanding. In reality everything is singular. In other words, concepts like ‘species’, ‘redness’, or even ‘man’, which name a range of objects that are united by some common form or feature, are purely inventions of the human understanding: ways of collecting together many individual objects for psychological simplicity. In reality there are only individuals. Universals do not exist. In modern terminology, this makes Occam a ‘nominalist’, and opposed to Plato’s idea of abstract, universal forms that are the archetypes of individual, material objects. Along with nominalism, the principle of ‘Occam’s Razor’ can also be seen as a reflection of an atomistic world-view. In some sense a precursor of the logical atomism of Bertrand Russell and the early thought of Wittgenstein, Occam held that reality is ultimately composed of simple, singular objects that exist independently and absolutely. No single thing depends on any other for its existence and change is merely the re-ordering and rearranging of singulars. These singulars, according to Occam, gained their existence by being posited by God but remain independent of any divine machinations in their causal and operative powers. In this way, Occam upholds both the possibility of free will and moral responsibility in human affairs.

Probably first posited by Aristarchus of Samos around 340 BC, Copernicus revived the idea that the earth and planets revolve around the sun, which remains in a fixed position.

Although Copernicus claimed his work was no more than hypothetical, eventually the weight of evidence would be too great to be resisted, and before long Copernicus would famously be supported by Galileo Galilei, Johannes Kepler and Isaac Newton amongst others. By the end of the following century Copernicus’ idea would be refined to the point of irrefutability.

De Revolutionibus Orbium Celestium,

‘Copernican Revolution’ to describe world-changing ideas.

Italian Renaissance,

The Prince,

In The Prince, Machiavelli concentrates on those techniques a successful politician must use if he is to achieve his political ends, without regard to the moral justification of the means thereby employed. Often criticised by detractors for its lack of moral sensibility, it is nevertheless a work of great intellectual integrity and consistency.

rarely speculating on the rightness or wrongness of the methods adumbrated therein.

Machiavelli thinks there are three primary political ‘goods’: national security, national independence, and a strong constitution.

In the Discourses, he provides more detailed background as to what he thinks makes a good and successful constitution. His political ideal is the republic run by the Princes, leaders of the principalities, but held in check by both the noblemen and ordinary citizens, all of whom share a part in the constitution.

Dutch humanist philosopher and theologian, Erasmus was the illegitimate son of a priest and was himself forced into a monastic life by his guardians.

The Praise of Folly.

In Praise of Folly has a dual purpose. On the one hand, Erasmus uses it as a vehicle for satire and invection against the offices and institutions of the Church, for which he had developed a deep hatred during his time at Steyr.

More’s vision of Utopia is a kind of Christian communism

More managed to complete his most important philosophical work, Utopia in good time, 1518 in fact, before Henry took his head in 1535.

Bertrand Russell probably sums up the problem with More’s vision, when he says, ‘life in More’s Utopia, as in most others, would be intolerably dull. Diversity is essential to happiness, and in Utopia there is hardly any’.

‘The repetitive occurrence of an incident does not guarantee that the same thing will happen again’

English philosopher of science, Francis Bacon was the forerunner of the famed British school of philosophers that include Locke, Berkeley, Hume, J. S. Mill and Bertrand Russell.

Bacon’s important works include The Advancement of Learning, New Atlantis...

Bacon was also an essayist and enjoyed a successful legal and political career, in particular after James I’s succession of Elizabeth, whereupon he was made Lord Chan...

Attributed as the originator of the saying ‘know...

What was needed, insisted Bacon, was a new way of collating and organising data that would help generate inductive hypotheses.

The previous instances do not guarantee anything about the following instance.

Bacon saw that the answer to this problem lay in placing the emphasis of investigation on looking for negative instances to disconfirm hypotheses, rather than finding ways of confirming them. This is a striking precursor to Karl Popper’s twentieth century falsificationist scientific methodology and his much vaunted claim of ‘solving the problem of induction’. As Popper readily admits, he owes much to Francis Bacon.

British philosopher and author of the famous political treatise Leviathan. Although he made important contributions in a number of other fields, including geometry, ballistics and optics, it is for his work as a political thinker that Hobbes is best known.

Unlike Descartes, his concerns were more political than epistemological, but he borrowed from him, and other contemporaries such as Galileo and Newton, the idea that if the natural sciences could be underpinned by axiomatic laws of nature, then this should also be the case for the social sciences. Hobbes’ method was to apply the rule of natural law to the realm of politics.

the Leviathan.

According to Hobbes man acts according to certain natural laws. In an analogy reminiscent of Newton’s first law of motion, which says matter will behave in a uniform way unless acted upon, Hobbes believes the natural state of man is one of war and strife, unless acted upon and governed by the rules of social living. Only a covenant kept by the rule of the sword can keep man from falling back into his natural state. Without the covenant, Hobbes tells us, society would disintegrate and it would be ‘a war of every man, against every man’ and the result would inevitably be that the life of man would be ‘solitary, poor, nasty, brutish and short’.

For Hobbes, free will and determinism were not mutually exclusive, but compatible notions. Just as water is unconstrained and yet will always flow to earth, so is man free but constrained by natural law. So long as a man is free to follow his natural inclinations, which ultimately are to survive and multiply, he is free to act. That his inclinations are determined by his nature presents no problem for Hobbes.

Philosophiae Naturalis Principia Mathematica contains his theory of gravity and laws of motion.

The insight behind Newton’s physics was that the universe runs according to law-governed mechanical principles. This idea was to have a profound influence on John Locke, whose philosophy may be seen as the philosophical working out of Newton’s physical principles.

It is thanks to Newton that empiricism began to enjoy a period of dominance over rationalist philosophy. However, Newton owed much to Descartes’ thought, and it is likely his own speculations could not have begun but for the work already undertaken by his rationalist predecessor.

Undoubtedly Newton’s greatest achievement was his theory of gravity, from which he was able to explain the motions of all the planets, including the moon.

It was a striking achievement that would not be superseded until Einstein, although even with the advent of Einsteinian relativity, Newton’s mechanics still holds good – and indeed is still used, on account of its simplicity, for predicting the movement of so-called ‘medium-sized’ objects – anything that is neither bigger than the solar system nor smaller than the eye can see. Newton’s work is a profound and remarkable achievement in the history of human thought.

French philosopher and mathematician, Descartes is often called the father of modern philosophy. Known to physicists as the discoverer of the law of refraction in optics, Descartes’ most famous work is in philosophy. Meditations on First Philosophy set the agenda for speculation in the philosophy of mind and epistemology for at least the next 300 years.

‘cogito ergo sum’,

where to start?

To begin with, Descartes notes that many of his beliefs are derived from his senses, or from perception. He notes that the senses, however, can often mislead. A stick may look bent when viewed half submerged in water, the true size of the sun and the moon is many times greater than would appear from sight, and so on. One can even suffer hallucinations such that what one thinks to be there does not exist at all. Descartes resolves not to trust completely that which has deceived him once, and therefore rejects any information from the senses as being uncertain and fallible.