Jonathan Edwards: The End for Which God Created the World (1749), Nature of True Virtue (1749) and Original Sin (1758)

Jonathan Edwards 1703-1758

It appears that the first philosophers of the later United States of America were either politicians or clergymen. Jonathan Edwards (1703 – 1758) belongs especially to the latter group, and as is to be suspected, the topics of his works are rather biblical. Yet, they contain some obvious references to philosophical discussions of the time, and writers like Locke, Hutchinson and Hume are explicitly mentioned.

I shall begin somewhat nonsensically from the latest work, the posthumous book on original sin, mainly because the biblical/philosophical -ratio is heavily balanced on the biblical side. Edwards' target is apparently John Taylor, who wrote a rather non-traditional work on original sin, in summary proclaiming that it is actually not a biblical doctrine. I shall not go into great details to Edwards' argumentation that the doctrine does have a background in Bible. Far more interesting are the slight bits of philosophy hidden among all the biblical quotes and exegesis. For instance, Edwards considers the at first sight rather odd demand that Adam as the first human being could be seen as forming a one entity with all his progeny, thus making it reasonable to punish all mankind for Adam's sin. Edwards defends this view by simply noting that God as the creator of all laws, moral and natural, can decide that there is a lawful connection between the sin of Adam and the guilt of all humankind. Edwards thus jiggles towards God, when it comes to the famous Euthyphro dilemma: does God decide what is good or is good independent of God's decision?

Edwards also tries to answer the rather obvious criticism of original sin that an assumption of an inborn tendency to evil would undermine all morality, which can be applied only in cases where a free choice is made by the will – if a person already has a tendency to certain actions, he cannot be thought responsible of them, unless this tendency follows from an earlier sinful choice leading to that tendency. Edwards sees a problem in this argument. If one could not determine the guilt of someone not merely from his tendency to do evil actions, but only from a sinful choice, an infinite regress would ensue. The choice itself would be an action, the sinfulness of which could not be determined by a mere tendency to do such choices, if the chooser is to be responsible. Thus it would have to be caused by a further sinful choice and so on. In effect, Edwards is arguing that either all notion of responsibility must be null or then even a given tendency to do evil things can be judged evil. Edwards is obviously endorsing the second prong of the dilemma, but it might well be asked whether his arguments could be used for denying validity of all moral evaluations.

The short writing on the end of the world has also a religious theme and Biblical exegesis is also used as an argument, but the work contains also interesting arguments. The main result of the work feels rather Neo-Platonist: God must, as it were, emanate and let his perfection become an active force, or otherwise it wouldn't be so perfect. In other words, God is like an artist that must unleash his creativity and create a world that perfectly reflects himself. One might of course ask why God has not created world for the living beings and their happiness and think of God as self-centered, because of his motives, but Edwards notes that the two ends need not necessarily contradict one another. To this end, Edwards introduces an important distinction between ultimate and final end. Final end is just an end that is not means and there could well be many final ends. Still, some of these final ends are more important than others and most important of these is what Edwards calls the ultimate end.

Edwards also explains the distinction between final and ultimate ends through the following analogy. Picture a man who tries to get married, not for the sake of anything else, but for the sake of marriage itself. The marriage is thus a final end of the man. Now, after the marriage is in force, the man might have another final end, like living a peaceful life of a husband. Still, the original ending was more ultimate, because the man couldn't have even hoped for the new final end without first reaching the first end. Similarly, one might imagine that God had at first just the final end of creating the world as a representation of his own glory, but later on God decided to also care for the denizens of the world. Note the interesting hint that Edwards might apply temporal terms to God's existence, which appear to imply that even God could change his mind.

The work on the nature of true virtue seems by far the least finished, but it is most clearly a philosophical work, but I will only have space to note some interesting points. The true virtue for Edwards is the love of God as the true source of all being. In other words, in loving God, a person loves also everything else, as reflecting God, while mere love towards anything else – even the whole universe – will contain only a limited fraction of all the possible love and will thus be deficient and even evil in comparison with the ultimate love. Out of this rather religious and mystical basis Edwards manages to make rather intriguing comments on ethics in general.

For instance, Edwards raises the question whether self-love can be a basis of virtue. He notes that the question is actually ambiguous, because self-love can be understood in two different manners. Firstly, self-love might just refer to a want of feeling good. In that sense, Edwards states, self-love can truly be basis of virtue, because, contrary to Kant would later say, even a virtuous person can and even should feel good about what he does – by loving and helping others, one also loves and helps oneself.

Secondly, self-love might also mean caring for one's own advantage. Such a selfish desire will inevitably restrict one's love in some manner and will thus close of a person from true virtue, Edwards concludes. Then again, he admits that such selfishness need not be completely closed off from love of other people. A selfish person might well note that e.g. taking care of some limited group of persons (say, one's family or country) one does good to oneself also. Thus, self-love in the second sense can at least be basis of limited love of others.

Edwards also discusses the idea of Hume and Hutschinson that morality is ultimately not based on reasoning, but on some feelings, like sympathy. Edwards agrees with the sentiment partially. He admits that morality is quite likely to be genetically based on feelings. Indeed, he suggests that God himself must have instilled such instinctual feelings to human mind, in order to guide them towards good life. Then again, Edwards does not accept the idea that feeling would be the ultimate foundation of all morality – even if we would become aware of morality through feelings, this does not mean that we could not argue for morality through proper reason. Edwards especially wants to steer away from the idea that a beginning of morality in feelings would make morality somehow relativist. Instead, Edwards emphasises that certain basic moral sentiments are spread universally throughout human race and are therefore most likely absolute decrees of God.

The works of Edwards show thus an interesting interaction between religion and philosophy that has been quite apparent in the few American philosophers I have now read. Next time I shall move back to the Old World and to laws of England.

Edmund Burke: A vindication of natural society (1756) and A philosophical enquiry into the origin of our ideas of the sublime and beautiful (1757)

Edmund Burke (1729 – 1797) is probably best known for his work against French Revolution, but before that he also published these two interesting writings. First of these is, at least according to the editorial introduction, a satirical pastiche aimed against Lord Bolingbroke, leading deist of the time. Bolingbroke had argued that original Christianity had been defiled through centuries of convention by all sorts of mystical rituals, which were disastrous to believers and against reason, thus calling for a return to this supposed natural belief. Burke makes an analogical move and argues that by same token civilized societies are artificial and therefore a return to natural state is in order.

Vindication might be satirical, but Burke's argument can be taken quite seriously. The existence of polities and states has meant almost a constant continuation of territorial skirmishes, often leading to total warfare. If Hobbes had thought that commonwealths were founded as an antidote to constant battle, the medicine proved to be even more poisonous, Burke points out.

Even in times of peace, a commonwealth is not a pleasant place to live, Burke continues. If the power lies in the hand of a single individual, freedom of everyone else is subdued under a tyrannical power. The case is not mush better, if the power is given to a small group of aristocrats, because that just means there are more tyrants to subdue everyone. Even democracies are far from pleasant, because the people or rabble can be even more intolerant in its decisions than all tyrants together – besides, rabble usually just follows some demagogue and thus produced just a new tyranny.

These arguments are interesting, because they sound quite similar to what one might expect from, on the one hand, anarchist, on the other hand, libertarian thinkers – states are a form of oppression that artificially divide the world into hostile areas. Of course, one could be more of a Hobbesian and ask whether living in societies has some positive consequences, which would weigh more than the supposed loss of freedom. Another question is whether the supposed natural or original state of humans is not just another artificial construction, which just reflects the mores of our own times.

Second work I shall study is Burke's book on philosophical aesthetics. It was a success at least on the continent, and such German philosophers as Moses Mendehlsson and Immanuel Kant were inspired by his work. Burke's basic attempt in the book is to explain the difference between two aesthetic notions, sublime and beautiful. Of the two, beauty seems a more familiar concept, so I am going to begin with it, although Burke prefers the opposite order.

A common idea of beauty has been that it has something to do with harmony and is thus mathematical in nature, because harmony is defined by numerical proportions. Burke has a bit of fun with the idea, noting that our sense of beauty is immediate and not dependent on taking exact measurements of e.g. limbs of an animal. A related theory of beautiful has connected beauty with fitness or utility, which is often decidable by mathematical proportions (for instance, an animal with limbs quite out of proportion cannot live). But Burke will have none of this. True, we do find quite unhealthy specimens grotesque, but we do also meet often healthy animals and people that we do not think beautiful.

Instead, Burke characterizes beauty through the notion of love, which beautiful things make us feel. Here, love appears to be used not in any Platonic, but in quite sensuous sense. Indeed, when we hear Burke describing smoothness as one type of beauty and read him describing the lure of a beautiful roundness of female breasts, it becomes rather obvious that Burke's love is more like sexual or at least sensual titillation. Quite noteworthy is then that Burke's description of beautiful seem to come from the perspective of a heterosexual male: beautiful thing must be small and weak,just like beautiful women are supposed to be. We might then say that Burke's notion of beauty is quite conservative, but at least open about its bias.

What is remarkable is that Burke allows a variety of different aesthetic notions: in addition to beautiful, we also have sublime. Of course, the notion of sublime is not Burke's own invention, but goes back to Longinus and his work on the topic. Sublime, Burke notes, is not a species of beautiful, but more like it's opposite. While beauty is connected with love, sublimity is connected with fear – it is pleasure caused by great proportions and immeasurable quantities that overwhelm us. While fear itself is not a pleasant feeling, sublime objects can awaken a sort of second order feeling, in which we reflect on our primal sense of fear and discomfort and find pleasure, when we understand and win our fear.

The notion of sublime is interesting, because it widens the realm of aesthetic notions – thing doesn't have to be traditionally pretty to be aesthetically interesting. Indeed, we could raise the question, whether the two notions truly are all the the aesthetic feelings we are capable of. If our sense of beautiful is caused by sensual titillation and our sense of sublime is caused by fearsome awe, could objects and events causing feelings like nausea or boredom cause also similarly aesthetic emotions as happens in case of sublime objects

Burke has still plenty of interest to say about e.g. the aesthetic effect of words (Burke notes that, unlike many modern thinkers had thought, words need not constantly produce images or representations of things they mean, but they can directly cause feelings, for instance, because of constant use – if virtue has been spoken of in suitably solemn occasions, the mere word will rouse that same solemn feeling again). Still, I am going to leave Burke's aesthetic theories here and move on to another philosopher.

Étienne Bonnot de Condillac: Traité des sensations (1754)

When I last spoke ofCondillac, I mentioned that he was interested of the phenomenon of feral children, that is, children that grew up in savage conditions, without any contact to humans, and therefore did not have any possibility to learn language – he especially mentions a case of a child being raised by bears in Lithuania. Obviously such a child cannot have all the mental capacities of a child raised in civilised surroundings, but Condillac emphasises more what the child can do – e.g. distinguish herself from her surroundings, make generalisations and simple logical deductions etc.

A natural problematic is then how much of conceptual infrastructure a conscious being would have, if its mental capacities were diminished from those of an average human being. Condillac proposes an interesting thought experiment to this effect: let us consider a living statue that would otherwise resemble a human being, but would have only one sense, say, smell, and see what concepts this person could have.

It seems rather arbitrary why Condillac would have picked up smell as the starting point, but apparently Buffon considered it to be actually a sort of primary sense with animals. Indeed, we could well imagine an organism (probably living in water) that would only react to the presence of some harmful chemical by running away and to the presence of beneficial chemical by moving towards the supposed source of the chemical.

Condillac supposes that even an entity with such meager sensory input would have all sorts of ideas. He would notice that odours change, he could recognise some odours as resembling previous odours and he might classify odours into e.g pleasant, neutral and disagreeable. Furthermore, he could think of himself as the subject of the changing pattern of odours and he could associate pleasantness of the odours with his own well-being. Of course, in all of this Condillac supposes, just like in his first work, that no new mental capacities are required for passing from mere sensation to memory, intellect etc.

What is more interesting is the set of ideas that the odour-limited human being would not have. Clearly with mere smells there is no sense of space, but Condillac notes that temporal consciousness would also be deficient, because one couldn't make realiabe measurements of the passing of odours. Furthermore, the Condillacian statue would not have any notion of things separate from himself, as she would have no idea that odours were something else than just ever changing part of her own mental life.

Condillac then considers what would happen if the sense of smell would be changed to taste or hearing – nothing much is the expected conclusion. Even a combination of two or all of these three senses would not change the situation much. At most, the statue could make comparisons between the sensations of different sense and would then note that e.g. odours are somehow different from sounds. We might then also in a sense measure the progress of sensations of one sense by comparing it with the progress of sensations on another sense, thus making the notion of time more concrete.

Rather unexpectedly, the case of vision is not that different, says Condillac. True, a statue with nothing but vision would have an idea of two-dimensional space, but it could not have any notion of three-dimensional space nor of any bodies independent of the statue. One might object to Condillac that while a field of vision truly is two-dimensional, movement and ensuing changes in visual images would make the statue able to conceive three-dimensionality. Indeed, this is what philosophers like Descartes had assumed – we could geometrically count e.g. the distance of ourselves from an object just from its shape and apparent size, when looked at different angles.

Condillac is here following Berkeleyan criticism of the traditional Cartesian theory of vision: without the help of other senses, constantly changing visual images would appear incomprehensible. It is only by associating different groups of variable visual images to different tactile sensations that we can truly see e.g. a rose as an object independent of ourselves. The addition of touch thus perfects the human statue at least to a level of a feral child.

One might wonder, which side of the debate is more correct. Certainly the theory of Cartesians cannot be true in the sense that we would consciously make difficult calculations in order to make sense of our visual field. Still, we might suppose human beings have an automatic and instinctual ”program” that would calculate the results without any need of actual calculation. A more convincing argument against Cartesians would be that movement in a computer-generated virtual space does feel a bit weird, possibly because the tactual sensations do not correspond with what we see.

So much for Condillac, next time I shall turn my attention to an English philosopher.

Samuel Johnson: Elementa philosophica: containing chiefly, Noetica, or things relating to the mind or understanding: and Ethica, or things relating to the moral behavior (1752)

Samuel Johnson (1696 -1772)

Returning from the Old to the New World we meet the reverend Samuel Johnson and his Noetics and Ethics. The title page of the work reveals a connection to an earlier figure I've spoken about: the book was printed by none other than Benjamin Franklin.

What is more interesting is Johnson's connection with bishop Berkeley. It should be best to point out first that Samuel Johnson I am speaking of is not the Samuel Johnson who wrote the first dictionary of English and famously argued against Berkeley by kicking a stone – that man lived in London. This Johnson was in fact quite appreciative of Berkeley's philosophy and had even met the reverend, when Berkeley was visiting Rhode Island.

While Berkeley's most famous philosophical works are quite focused on few central topics – e.g. that existence can be defined through capacities of being perceived and perceiving, that matter as neither perceptible nor perceiving does not exist and God causing our perceptions directly – in Johnson's book these topics are barely mentioned. The first part, Noetics, focuses on questions that in continental Europe were addressed in books on logic: how does human mind work and how it is to be properly educated and used. Berkeley's theses work as a sort of ontological underpinning of this methodological framework – a novel attempt, at least.

Johnson's take on Berkeley's philosophy seems rather peculiar. He appears to think that the essential message of esse est percipi is that everything we see is as it is – there is no reality behind perceptions, which can then be directly identified with things themselves. So, we do know that there are horses, because we definitely see them running about. This is, of course, what Berkeley himself professed – he thought he was upholding the common sense against sceptical attacks inherent in Locke's philosophy.

More peculiar is that Johnson at once assumes many ontological notions Berkeley had suggested were quite unnecessary and meant really nothing. Thus, while Berkeley thought there was no reason to speak of any substance or substrate behind perceived properties, Johnson notes there is a perfectly valid sense of substance – certain combinations of simple perceptions just are substances. Furthermore, Johnson also find a use for the concept of matter, which Berkeley had discarded as leading to skepticism – material things just are those that are defined by being perceived. All of this is a symptom of Johnson taking universalisation and abstraction far more seriously – an understandable view in a study leading all the way to scientific generalities.

After the Berkeleyan underpinnings Johnson's Noetics seems a rather traditional work – once he gets to the level of concepts, he can just follow in the footsteps of traditional syllogistics. He also presents a rather traditional metaphysical account of world – being perceived (being acted upon) and perceiving (acting) define two kinds of beings, material things and spirits. Clearly spirits as the more active component are somehow more robust and more essential. Behind all the material things and spirits lies the perfect spirit or God.

Johnson's Ethics feels even more traditional. The aim of the second part is to secure human happiness, which is one purpose of God and which results not through excessive pleasure, but through moderation. Indeed, Johnson can point out to a result from Noetics that spirits are somehow more important than material things, which are nothing more than mere perceptions – one cannot find true happiness with mere passive perceptions, but it must be found in spiritual matters.

So much for Samuel Johnson, I'll now return to Condillac.

George-Louis Leclerc, Comte de Buffon (1707 - 1788)

Buffon himself

If one wants to investigate the development of biology into its modern shape, one must surely study the works of Buffon. Including him in a discussion of philosophy might seem less reasonable, but considering the importance of Darwin's theory of evolution to a modern way of thinking and Buffon's value as a step towards Darwin, his inclusion seems more understandable.

Buffon's main work is Histoire naturelle, a huge, multivolume study on such varied topics as cosmology, geology and biology. Going through all of these volumes would be an arduous task, and so I've chosen to read only a selection of what should be especially philosophical portions of Buffon's works. Even in comparison with this selection, my post will be just a quick summary of some interesting features found in Buffon's writings.

We might begin from Buffon's methodological remarks. Buffon sets out himself between what he considers two faulty extremes. First of these extreme was symbolised by Aristotle, who according to Buffon had no real method at all in his biological writings – he just enumerated arbitrary observations on the behaviour of animals, without trying to make the observations into a coherent system. The other extreme, on the contrary, tried to use an artificial, rigid and external classification for making sense of the living world – Buffon mentions especially Linné as a representative of this group. Buffon's own attempt is to find natural classification and systemification of nature. Of course, one cannot just directly start from such a classification, but one can still try to proceed toward such a classification – man-made classifications are only a starting point, which must be constantly compared with empirical data.

A good example of Buffon's reliance on empirical data is his attitude towards the history of Earth. While some of Buffon's contemporaries still tried to fit Earth's development with the account of Genesis, Buffon wanted to justify his view of Earth's history more through proper research. Of course, he still wasn't ready to throw out all of the Bible and accepted, for instance, the idea of a worldwide deluge. Yet, he didn't base this idea merely on Bible, but also noted how fossils of sea animals could be found on dry land.

Fossils were indeed an important piece of evidence for Buffon, because they show that animals of previous times have been different than they now are – elephants of ancient times (mammoths, that is) were considerably larger than they current counterparts. Buffon still isn't an evolutionary thinker, but believes that there has been a fixed number of species since the generation of life on Earth. These species could have varied in their features and especially they might have degenerated, like elephants have become smaller – earlier Earth had more vigour in producing animals, Buffon explains. Still, no truly new species is ever born. Here he justifies once again his statement through fossils – all species of current times have been found from fossil sources.

Although Buffon believes in the fixedness of certain genera of living things, he does think there is a certain continuum of life. For instance, he suggests that there is no clear division between plants and animals, because certain entities, like corals, share features of both animals and plants. Somewhat inconsistently, Buffon then insists on a leap from the level of animals to the level of human beings. While animals are irrational, human beings are rational, and there cannot be any middle road between irrationality and rationality. This very traditional division implies, according to Buffon, that while for animals mere satisfaction of physical desires is enough, human happiness relies on harmony between reason and sensuous impulses.

The most intriguing aspect of Buffon's thought is then how he manages to unify quite revolutionary ideas with some rather traditional and even conservative thoughts. Earth and especially its living denizens have a history, but this history does not entail that all species are related to one another.Living beings form a continuum, but humans are still far removed from other species.

As most of Buffon's works concern rather specific questions of biology and other particular sciences, I shall leave my account of his work to this rather general level and turn again to American philosophers.

Étienne Bonnot de Condillac: Essai sur l’origine des connaissances humaines (1746)

Enlightenment thinker Condillac (1714 - 1780)

If one wanted to name one philosopher as the strongest influence on works of abbé Condillac, it would clearly be John Locke, which is shown well by Condillac's first book, which investigates the origin of human knowledge. Almost all other modern philosophers are discarded, because they have based their philosophies on abstract principles, which Condillac considers to be a completely topsy-turvy method, because such principles are usually the most difficult topic to master properly. Condillac makes especially fun of Christian Wolff's metaphysics: Wolff defines e.g. existence as a complement of possibility, although this statement tells us almost nothing about existence or possibility, and indeed, fails to note that existence is actually the more fundamental notion.

It is then no wonder that Condillac instead wants to begin with what we experience. Experience provides us with ideas, which we then can use as building material for further ideas (e.g. we can abstract the idea of horseness from ideas of individual horses, or we could combine idea of a headless body of a horse and idea of human head to form the idea of centaur). It is by analyzing the genesis of our ideas that we make them clearer and gain a better understanding of what we actually know, while of abstract principles and concepts we usually have only a very murky idea. This is all very Lockean, as is the division of ideas into simple (certain shade of green) and complex (green apple).

What Condillac develops more than Locke is the psychological framework of different mental capacities required for turning perceptions into knowledge and complete science. What is truly remarkable is Condillac's attempt to reduce all mental phenomena into nothing more than sensation and attention. It is undoubtedly to be expected that according to an empiricist sensation would be the origin or basis of knowledge, but it truly appears radical to say that sensation is almost all there is to human mind. Thus, we sense things and we can choose some object as the focus of our sensation, but we can also focus our attention on the fact that what we now sense is something that we have sensed earlier – this is just what memory is about and therefore, Condillac concludes, memory is just another form of sensation.

Now, I find this reduction of all mental faculties into sensation deeply problematic, because there could be organisms that sense, but still fail to have e,g. memory. Such an organism could, for instance, note the presence of a certain chemical, detrimental to its condition, in its environment and then react with a movement taking its backwards, away from the source of that chemical. There's no need for any memory, just an unpleasant feeling and an automated reaction to that feeling. The existence of such an organism would be even evolutionarily reasonable, because this capacity would greatly enhance the survival of such an organism.

Indeed, a capacity for memory appears to require something else – some way to storage features of past sensations. Of course, this requirement of memory storage seems more imminent in a materialistically grounded theory of consciousness. Condillac, in yet another move away from Locke, commits himself to a non-materialistic theory of soul, and for reasons that strikingly remind one of Wolffian psychology: self-consciousness just cannot be explained through a complex substance. It is probably more reasonable to suppose that to such an immaterial soul it is just a matter of directing your attention to view some sensation as resembling past sensations.

Yet another area in which Condillac goes beyond Locke's philosophy is the role of language, which Condillac admits is almost a necessity for more abstract ideas and required, for instance, in advancing mathematics beyond simple calculations. Condillac even provides the reader with a hypothetical history of forms of language, starting from what Condillac calls a language of action, by which he apparently means a language using natural gestures and cries for communicating one's thoughts and emotions to others.

It might be that Condillac understood the importance of language from the example of ”wolf kids” who had grown up outside human communities and learned language only later in their life – at least this is a topic Condillac was quite interested of. It might also be an inspiration for Condillac's main work, in which he experiments with the idea of a person born without all the senses and upbringing of an average Frenchman – but this is a topic I'll return to later.

D'Alembert: Traité de dynamique (1743)

Jean le Rond d'Alembert is a name more often heard in a history of mathematics than in a history of philosophy. Yet, his connections to the world of philosophy in French Enlightenment are not non-existent, because he was one of the editors of the famous Encyclopédie, an encyclopedia meant to cover all human knowledge of the time. D'Alembert was particularly entrusted to care for all the articles engaged with natural sciences, but he also wrote a preliminary discourse explaining the purpose of the work and also engaging with some philosophical underpinnings of it and presenting a general framework for all sciences.

The book I am engaged with here belongs on the surface to d'Alembert's more scientific works, as even the name suggests. In effect, the purpose of d'Alembert in this treatise is, firstly, to present some fundamental principles for movement of material objects, such as inertia, and secondly, based on these principles, to solve some tricky problems, in which, for instance, the velocity of a body hanging from a thread is to be determined.

The topic of d'Alembert's treatise is then something that modern students of physics might find useful to consider. On the other hand, d'Alembert's method of presenting his result has some quaint elements, which show his work to belong to a transitional period between a geometric presentation of Greeks and algebraic presentation familiar in modern mathematics and physics. This is firstly shown by d'Alembert's assumption that everyone knows truths that have been demonstrated by Euclid in his Elements, as he without any explanation refers to a property of a circle that if two lines AB and AC are drawn from the same point A outside circle so that AB touches the circle on B and AC goes through a point D of the circle and then cuts circle also in the point C, then the square of the side AB equals a rectangle formed by AD and DC or AD x DC. While a modern student of mathematics might even have some difficulties following this description, let alone being convinced of it, any connoisseur of mathematics from d'Alembert's time would instantly recognise this statement as the proposition 36 in the third book of Euclid'sElements.

Even more clearly this transitional nature is seen in d'Alembert's habit of embodying quantities like velocity, time and others with lines, which for an eye unused to geometric way of presentation seem to have no connection with each other, although one acquainted with this method could see what mathematical relation the different lines are supposed to exhibit. Then again, in more difficult cases d'Alembert prefers algebraic denotations of mathematical relation. What makes it all even more confusing is that while d'Alembert clearly had an inkling that some quantities (e.g. forces) have a direction, neither the geometric presentations nor algebraic formulas clearly distinguish between scalar and vector quantities. Add to all this the rather muddled view of infinitesimals at the time, in which e.g. differentials of various levels were represented by lines that are supposed to be infinitely small, and a modern reader is bound to feel some puzzlement.

Philosophically most interesting part of the book is, as is often the case with such treatises, the preface. Here we find d'Alembert's take on the muddled question of ”living forces”, seemingly physical problem that still interested such philosophers as Descartes, Leibniz and Kant. The controversy itself started from the apparently obvious notion that something remains same in various interactions of bodies, such as collisions and that this same element would represent the quantity of motion itself. Descartes, among others, had suggested that this must be what is nowadays called momentum or mv, in which m means mass of the bodies involved and v their velocity. Some people, such as Leibniz, objected that what is conserved is actually a more intricate quantity, ½(mv^2). Leibniz also asserted that this quantity expressed a living force of the moving bodies themselves, while momentum was connected only with dead forces affecting bodies externally.

D'Alembert strategy, at least in the first edition of the treatise. is to deny that there is any true controversy. Momentum is conserved in momentanous collisions of bodies, while Leibnizian quantity of motion is conserved in cases where e.g. a medium continuously resists the movement of a body. Now, the case of a resisting medium can be regarded as an infinite sum of infinitely small collisions, which mathematically means that Leibnizian quantity of motion must be an integral of momentum, as it truly is. Which one to take as the more essential expression, d'Alembert concludes, is just a verbal quibble.

Although d'Alembert's solution is, as far as I know, quite correct, it also expresses a more general tendency of disregarding all philosophical problems as verbal quibbles – something quite common for modern scientists. This tendency is shown by d'Alembert also with a question concerning the status of physical laws : are they necessary or contingent? D'Alembert attempts once again to show that both sides are in a sense correct: laws of physics are contingent, because world could have worked according to different laws, but they are also necessary, if you take into account the empirical evidence about the motion of bodies. D'Alembert fails to notice that he has actually endorsed one side of the dilemma – contingency – and rephrased the other side, so as to fit with the first side. Furthermore, from a modern viewpoint, he has accepted a rather strong position . Not many would accept that empirical data would fit in with just one physical theory and thus necessitate it.

So much for d'Alembert, next time another philosopher from French Enlightenment.