Saturday, June 10, 2017

Essential Thinkers #24 David Hume, Hero of Modern Day Sceptics and and Empiricists

David Hume (1711-1776) is the philosophical hero of modern day sceptics and empiricists, renouncing all knowledge except for that which can be gained from the senses. Alas, as W.V.O. Quine would later famously say, echoing Hume, what can be granted from the senses is, after all, not much.

From John Locke, Hume drew the conclusion that all human knowledge is based on relations amongst ideas, or ‘sense impressions.’ Anything not given in experience is mere invention and must be ruthlessly discarded. As a result he denies the existence of God, the self, the objective existence of logical necessity, causation, and even the validity of inductive knowledge itself. His aim is twofold: at once demolitionnary – to rid science of all falsehoods based on ‘invention rather than experience’ – and constructive, to found a science of human nature.

Much impressed with how Isaac Newton had described the physical world according to simple mechanical laws, Hume had a mind to do something similar for the nature of human understanding. His Treatise on Human Nature is a painstaking study in experiential psychology in search of general principles. In this Hume can be seen as having failed spectacularly, primarily because his whole taxonomy of ‘impressions’ and ‘ideas’ is derived from the much discredited Cartesian model. Nevertheless, Hume’s negative program is a devastating example of the power of logical critique. His sceptical results, especially regarding induction, remain a problem for modern philosophers.

Hume observes that we never experience our own self only the continuous chain of our experiences themselves. This psychological fact leads Hume to the dubious metaphysical conclusion that the self is an illusion, and that in fact personal identity is nothing but the continuous succession of perceptual experience. “I am,” Hume famously says, “nothing but a bundle of perceptions.

Following a similar line of thought, Hume notices that the force that compels one event to follow another, causation, is also never experienced in sense impressions. All that is given in experience is the regular succession of one kind of event followed by another. But the supposition that the earlier event, the so-called ‘cause,’ must be followed by the succeeding event, the ‘effect,’ is merely human expectation projected onto reality. There is no justification for believing that there is any causal necessity in the ordering of events.

Hume’s scepticism does not stop there. He regards human belief in causation as just a special case of a more general psychological trait: inductive reasoning. Inductive reasoning is the process that leads us to make generalisations from observing a number of similar cases (remember frictional character Sherlock Holmes?). For example, having observed many white swans but no black swans, one might seemingly be justified in the conclusion that “All swans are white.” Equally, being aware that men often die, we conclude “All men are mortal.”

But such generalisations go beyond what is given in experience and are not logically justified. After all, black swans were found in Australia, and there is always the logical possibility of coming across an immortal man.

Hume claimed that inductive reasoning could not be relied upon to lead us to the truth, for observing a regularity does not rule out the possibility that next time something different will occur.

Since all scientific laws are merely generalisations from inductive reasoning, this so-called ‘problem of induction’ has been an urgent one for philosophers of science. Trying to show how induction is justified has taxed them throughout the 20th century. Karl Popper is notable for offering the most promising solution to Humean scepticism.
[Summarized from Philosophy 100 Essential Thinkers by Philip Stokes, 2012.]

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Sunday, June 4, 2017

I Wonder #10 How Can I Fool A Lie Detector?

The polygraph test, still used widely in the US, measures your heart rate, breathing and blood pressure as a way to tell how stressed you are feeling. The idea is that the interrogator asks you questions and when you lie, you get more stressed than when you tell the truth, and the difference is revealed in the physiological measures. A simple way to cheat the polygraph is to deliberately distort your physiological readings when telling the truth, such as by biting your tongue, or imagining an embarrassing incident in the past. Similar problems afflict brain scan lie detectors, which follow the same principle of needing a reliable baseline against which to compare signs of lying.
[By Dr. Christian Jarrett, BBC Earth. Asia Edition/Vol.9 Issue 1]

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Wednesday, May 24, 2017

Essential Thinkers #23 John Locke, the Empiricist, on the Nature of Human Understanding

In his day, John Locke (1632-1704) was an important political figure and author of the liberal exposition Two Treatises of Government. An associate of the Earl of Shaftesbury, Locke spent time in exile in Holland, returning to England after the ‘Glorious Revolution’ of 1688. It is for his views on the nature of human knowledge, however, in his Essay Concerning Human Understanding that he is remembered in modern philosophy. 20 years in the writing, the book was to exert such an influence on the next 100 years of Western though that its author is considered by many to be the greatest British philosopher of all time. The works of George Berkeley, Immanuel Kant, and David Hume are all direct successors of Locke’s Essay.

The subject of Locke’s Essay, as given in the title, is the nature of human understanding, that is, the very way in which the human mind collects, organises, classifies and ultimately makes judgements based on data received through the senses. Greatly influenced by the scientific turn of his day, and a personal friend of two renowned contemporary scientists, Robert Boyle and Isaac Newton, Locke’s intent was to set the foundations of human knowledge on a sound scientific footing. He had read with great interest Rene Descartes’ Meditations on First Philosophy, but rejected the rationalist philosophy that underpinned its conclusions.

For Locke, there could be no innate knowledge: rather, everything we know must be derived from experience, through the actions of the physical world on our sense organs. This is the view now known as empiricism, a view still central, in essence if not detail, to the philosophies of W.V.O. Quine and other modern thinkers. Locke’s detractors, the Rationalists (Rene Descartes, George Berkeley, Gottfried von Leibniz) with whom the Empiricists battled for ideological supremacy throughout the 17th and 18th centuries, have their modern counterparts in the supporters of Noam Chomsky and his philosophy of innate, or generative, grammar.

Locke states that the mind at birth is like a blank slate, or tabula rasa, waiting to be written on by the world of experience. All human knowledge is derived from ideas presented to the mind by the world of experience. However, these ideas can be classified into two general sorts. There are complex ideas and simple ideas. Simple ideas are the immediate products of sensory stimulation, examples would be ‘yellow,’ ‘bitter,’ ‘round,’ ‘hard,’ and so on. Complex ideas are constrictions out of simple ideas, and are the product of internal mental operations. These include all our ideas of familiar material objects, such as tables, chairs, cats, dogs and horses. But complex ideas need not represent anything real in the world. This accounts for ideas like that of a unicorn, a complex idea itself made up of other complex ideas, such as ‘horse’ and ‘horn.’

Among Locke’s simple ideas is a distinction between those that are primary qualities of objects and others that are secondary qualities. The distinction divides those qualities thought to be essential and inherent to all objects and those that are apparent only on account of the effect objects have on our sense. Primary qualities are those such as solidity, extension, shape, motion or rest, and number. Secondary qualities are those such as colour, scent and taste. These are secondary because, according to Locke, they do not inhere in objects themselves, but are causally produced only in our minds by the effect of an object’s primary qualities upon our senses. Another way of conceiving them is to say primary qualities are objective (really exist) and secondary ones subjective (only exist in the minds of observers).

In the popular conundrum of whether a falling tree makes a sound when there is no one to hear it, Locke’s view would be that the falling tree creates vibrations in the air, but that there is no ‘sound’ strictly speaking, since sound is not a ‘real’ or primary quality. This view, sometimes called ‘scientific essentialism,’ leads to the metaphysical conclusion, plausible to many modern thinkers, that without a perceiving mind, there is no such thing in the world as colour or sound, sweet or sour and so on; but there are really such things as shape, extension and solidity, independently of whether anyone perceives them or not.
[Summarized from Philosophy 100 Essential Thinkers by Philip Stokes, 2012.]

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