Category Archives: Philosophy

Arts, History, Philosophy, Science

Quantum Leaps: John Dalton

1766–1844

FOR much of his life, the primary interest of John Dalton, an English Quaker, was the weather. Living in the notoriously wet country of Cumbria, he maintained a daily diary of meteorological occurrences from 1787 until his death, recording in total some 200,000 entries. It was, however, his development of atomic theory for which he is most remembered.

Different atoms – It was around the turn of the nineteenth century that Dalton started to formulate his theory. He had been undertaking experiments with gases, in particular on how soluble they were in water. A teacher by profession, who only practised science in his spare time, he had expected different gases would dissolve in water in the same way, but this was not the case. In trying to explain why, he speculated that perhaps the gases were composed of distinctly different “atoms”, or individual particles, which each had different masses. Of course, the idea of an atomic explanation of matter was not new, going way back to Democritus of Abdera (c. 460–370 BCE) in ancient Greece, but now Dalton had the discoveries of recent science to reinforce his theory. On further examination of his thesis, he realised that not only would it explain the different solubility of gases in water, but would also account for the “conservation of mass” observed during chemical reactions as well as the combinations into which elements apparently entered when forming compounds (because the atoms were simply “rearranging” themselves and not being created or destroyed).

Atomic theory – Dalton publicly outlined his support for this atomic theory in a lecture in 1803, although its complete explanation had to wait until his book of 1808 entitled A New System of Chemical Philosophy. Here, he summarised his beliefs based on key principles, including: atoms of the same element are identical; distinct elements have distinct atoms; atoms are neither created nor destroyed; everything is made up of atoms; a chemical change is simply the reshuffling of atoms; and compounds are made up of atoms from the relevant elements. In the same book he published a table of known atoms and their weights, although some of these were slightly wrong due to the crudeness of Dalton’s equipment, based on hydrogen having a mass of one. It was a basic framework for subsequent atomic tables, which are today based on carbon (having a mass of 12), rather than hydrogen. Dalton also erroneously assumed elements would combine in one-to-one ratios (for example, water being HO not H2O) as a base principle, only converting into “multiple proportions” (for example, from carbon monoxide, CO, to carbon dioxide, CO2) under certain conditions. Although scientific arguments over the validity of Dalton’s thesis would continue for decades, the foundations for the study of modern atomic theory had been laid and with ongoing refinement were gradually accepted.

Prior to atomic theory, Dalton had also made a number of other important discoveries and observations in the course of his work. These included his “law of partial pressures” of 1801, which stated that a blend of gases exerts pressure which is equivalent to the total of all the pressures each gas would wield if they were alone in the same volume as the entire mixture.

Dalton also explained that air was a blend of independent gases, not a compound. He was the first to publish the law later credited to and named after Jacques-Alexandre-César Charles (1746–1823). Although the Frenchman had been the first to articulate the law concerning the equal expansion of all gases when raised in equal increments of temperature, Dalton had discovered it independently and had been the first to publish.

Dalton also discovered the “dew point” and that the behaviour of water vapour is consistent with that of other gases, and hypothesised on the causes of the aurora borealis, the mysterious Northern Lights. His further meteorological observations included confirmation of the cause of rain being due to a fall in temperature not pressure.

Further achievements – John Dalton began teaching at his local school at the age of 12. Two years later, he and his elder brother purchased a school where they taught some 60 children.

His paper on colour blindness, which both he and his brother suffered from, and which was known as daltonism for a long while, was the first to be published on the condition. Dalton is also largely responsible for transferring meteorology from being an imprecise art on folklore to a real science.

Chronology  

. 1793 Meteorological Observations and Essays published

. 1801 Dalton states his Law of Partial Pressure

. 1803 Outlines his atomic theory in a lecture. This transformed the basics of chemistry and physics

. 1808 A New System of Chemical Philosophy published.

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Arts, Philosophy

(Philosophy) Kinds of truth

Shaping the world with the mind

Intro: Immanuel Kant recognised that while rationalism and empiricism presented opposing claims, both contained elements of truth. He argued that while we know the world through our senses, it is shaped by our minds

Representation of things

Kant (1724–1804) sought to establish the limits of what we can know about the world. Unlike his predecessor, John Locke, he argued that experience alone was unreliable: not only are we limited to our particular sense organs, when we do perceive something, we only perceive a “representation” of that thing in our minds, rather than see the thing in itself. A rose, for example, may appear red or grey to different animals, and so is only ever seen indirectly, as a construct of our senses.

Kant also argued that our psychological make-up shapes the world we perceive. Our minds are so constructed, he said, that we perceive things in terms of space and time, and that anything outside these parameters is beyond our understanding. He claimed that in a sense we project the concepts of space and time onto the world, and then perceive the world accordingly. A child, for example, learns the concepts “here” and “there” through experience, but it only does so because it innately understands the concept “space”. Likewise, the child learns the concepts “then” and “now” because it has an innate understanding of the concept “time”.

Transcendental idealism

Kant argued that innate concepts are what make experience possible, and he identified 14 such concepts. They are like lenses through which we both project and view the world. Kant was therefore neither a rationalist nor an empiricist – that is, he saw neither reason nor experience as our primary source of knowledge. He described his position as “transcendental idealism”.

The Noumenal World

Kant compared the way we perceive things to the way a painter presents an image of something. A painting may portray every detail of a scene, but it remains merely a representation of that scene, not the scene itself.

In the same way, our perception of an object is a mental representation, not the object as it actually is. We experience only the “phenomenal” world, which is accessible through our senses, but can never have direct access to what he called the “noumenal” world of things-in-themselves.

Categories of understanding

According to Kant, when we perceive an object, we shape it with our innate ideas of space and time: we project these ideas onto the object and then interpret it in those terms. He described space and time as innate “intuitions”, and distinguished a further 12 concepts, or “categories”, which he also claimed we understand innately and project onto what we perceive. He classified these into the four divisions of quantity, quality, relation, and modality.

. Quantity [Unity, Plurality, Totality]. These categories enable us to distinguish single things from many things, and to perceive many things as parts of a whole.

. Quality [Reality, Negation, Limitation]. Such categories give us the notions of something being real or unreal, and that of something having an extent or limit.

. Relation [Inherence/subsistence, Causality/dependence, Community/reciprocity]. The categories of relation enable us to perceive the properties of an object and to understand its relationships to other objects.

. Modality [Possibility/impossibility, Existence/non-existence, Necessity/contingency]. The modal categories enable us to know if something is possible or not, whether it exists or not, and whether it is necessary or not.

KINDS OF TRUTH

At the heart of Kant’s transcendental idealism is the idea that it is possible to have knowledge of the world independently of empirical evidence or experience.

A priori and a posteriori knowledge

Before Kant, many philosophers had realised that there are two kinds of truth: necessary truth and contingent truth. A necessary truth, such as “Circles are round”, is one that is true by definition, and so cannot be denied without contradiction. A contingent truth, such as “The sky is blue”, is either true or false according to the facts. Kant introduced two similar distinctions: firstly, between analytic and synthetic statements, and secondly between a priori and a posteriori knowledge.

An analytic statement, like any proposition, consists of a subject and predicate, but its predicate is implicit in its subject. For example, the statement “A square has four sides” is analytic because its predicate (“four sides”) is implicit in its subject (“square”), and so it is true by definition. Synthetic statements, however, have informative predicates, which tell us something new about the world. For example, “This square is red” is synthetic, because its predicate (“red”) is not contained in its subject (“square”).

Kant also identified two different kinds of knowledge: a priori knowledge, which is known independently of experience, and a posteriori knowledge, which is known through experience only. These two kinds of knowledge are expressed in analytic and synthetic statements respectively.

Kant also claimed that there is a third kind of knowledge: synthetic a priori knowledge, which is both necessarily true (a priori) and informative (synthetic).

Synthetic a priori truths

Before Kant, it was assumed that all a priori knowledge must be analytic – that is, if it is known without any empirical evidence, then it cannot tell us anything new about the world. However, Kant claimed that from a priori statements we can make deductions that are synthetic, and so tell us something about the world. Here’s some examples:

. Synthetic A Priori – “The interior angles of a triangle add up to 180 degrees.” This statement tells us something about a triangle that is not implicit in its definition, and is therefore synthetic. However, it is also an a priori truth, since, for Kant, it can be arrived at through rational reflection.

. Analytic A Priori – “A triangle is a three-sided shape.” This statement is analytic: the definition of its subject, “triangle”, is a shape with three sides. It is also an a priori truth, since we understand it without empirical evidence.

. Synthetic a priori judgements – According to Kant, we are born with no knowledge of the world, but we do have innate concepts that enable us to experience the world intelligibly. For example, we have a priori knowledge of the concepts of space, time, and causality, and these enable us to arrive at scientific and mathematical truths that are both synthetic (informative) and a priori (necessary). For Kant, the statement “3+3=6” is a synthetic a priori truth, because it is informative (it says more than “3+3=3+3”) and can be arrived at through reason alone.

. Philosophy: Modern Logic

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Arts, Philosophy, Science

Philosophy: The blank slate

INNATE IDEAS

Intro: In An Essay Concerning Human Understanding, John Locke rebutted the rationalists’ argument that we are born with innate ideas, and so laid the foundations for modern empiricist thought.

“No man’s knowledge here can go beyond his experience.” – John Locke (1689)

British empiricism

Central to the philosophy of John Locke (1632–1704) is the idea that there is no such thing as innate knowledge: at birth, the mind is what he called a tabula rasa, or “blank slate”. When we observe new born babies, he said, it is clear that they do not bring ideas into the world with them. It is only as we go through life that ideas come into our minds, and these ideas are derived from our experience of the world around us. This idea stood in marked contrast to much contemporary thinking, particularly the ideas of Descartes and Leibniz, who argued that we are born with innate ideas and that our reason, rather than our experience, is our primary means of acquiring knowledge.

Locke’s idea was not new – it had been defended by Francis Bacon and Thomas Hobbes, and even went back to Aristotle. However, Locke was the first philosopher to give a comprehensive defence of empiricism – the idea that experience is our principle source of knowledge. That is not to say that Locke dismissed the importance of reasoning in our acquisition of knowledge. He believed, too, that each of us is born with a capacity for reasoning, and that the right education is critical to a child’s intellectual development.

Learning the world

Locke claimed that there are two kinds of idea – ideas of sensation and ideas of reflection – and that the latter are made out of the former. In Locke’s words, the objects of the world “cause” ideas of sensation to form in our minds. We then organise these ideas into ideas of reflection:

Blank Slate – At birth, a baby brings no ideas into the world; its mind is completely blank. This means that everything that it will know will come from the world around it. For this reason, Locke claimed that the child should be exposed to the best ideas possible.

Ideas of Sensation – According to Locke, the objects of the world cause ideas of sensation in the infant’s mind. These simple impressions form in the way that light forms images on photographic film: it is a mechanical process that requires no effort on the child’s behalf.

Ideas of Reflection – As the child grows older, it builds ideas of reflection out of its ideas of sensation. From its interactions with other people, and its simple understanding of the qualities of a ball, for example, it can create the idea of “football”. From that, and other simple ideas, it forms the more complex ideas of “teamwork” and “competition”.

Primary and Secondary Qualities

According to Locke, we can only receive information about the world through our senses. This information, he claimed, is of two kinds, and concerns what he called the primary and secondary qualities. An object’s primary qualities, such as its height or mass, are objective, and exist independently of whoever is observing it. However, its secondary qualities, such as its colour or taste, may differ between observers. A ball, for example, may appear grey or multicoloured to two different observers, but both will agree on its size.

Primary Qualities – For Locke, the primary qualities of a thing are its length, breadth, height, weight, location, motion, and overall design.

Secondary Qualities – The secondary qualities of a thing are its colour, taste, texture, smell, and sound. These qualities depend on the perceiver’s senses.

NEED TO KNOW

. Although Locke denied the existence of innate ideas, he claimed that we have innate capacities for perception and reasoning

. In the 19th century, the notion of innate ideas resurfaced. Scholars questioned whether behavioural traits come from “nature or nuture”

. In the 20th century, Noam Chomsky extended Locke’s idea that we have an innate capacity for reasoning. Chomsky claimed that all humans have an innate ability to acquire language.

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