Archive for December, 2010

Dialogs over actions

In the post below, I mentioned the challenge for knowledge engineers of representing know-how, a task which may require explicit representation of actions, and sometimes also of utterances over actions.  The know-how involved in steering a large sailing ship with its diverse crew surely includes the knowledge of who to ask (or to command) to do what, when, and how to respond when these requests (or commands) are ignored, or fail to be executed successfully or timeously.

One might imagine epistemology – the philosophy of knowledge – would be of help here.  Philosophers, however, have been seduced since Aristotle with propositions (factual statements about the world having truth values), largely ignoring actions, and their representation.   Philosophers of language have also mostly focused on speech acts – utterances which act to change the world – rather than on utterances about actions themselves.  Even among speech act theorists the obsession with propositions is strong, with attempts to analyze utterances which are demonstrably not propositions (eg, commands) by means of implicit assertive statements – propositions  asserting something about the world, where “the world” is extended to include internal mental states and intangible social relations between people – which these utterances allegedly imply.  With only a few exceptions (Thomas Reid 1788, Adolf Reinach 1913, Juergen Habermas 1981, Charles Hamblin 1987), philosophers of language have mostly ignored utterances  about actions.

Consider the following two statements:

I promise you to wash the car.

I command you to wash the car.

The two statements have almost identical English syntax.   Yet their meanings, and the intentions of their speakers, are very distinct.  For a start, the action of washing the car would be done by different people – the speaker and the hearer, respectively (assuming for the moment that the command is validly issued, and accepted).  Similarly, the power to retract or revoke the action of washing the car rests with different people – with the hearer (as the recipient of the promise) and the speaker (as the commander), respectively.

Linguists generally use “semantics” to refer to the real-world referants of syntactically-correct expressions, while “pragmatics” refers to other aspects of the meaning and use of an expression not related to their relationship (or not) to things in the world, such as the speaker’s intentions.  For neither of these two expressions does it make sense to speak of  their truth value:  a promise may be questioned as to its sincerity, or its feasibility, or its appropriateness, etc, but not its truth or falsity;  likewise, a command  may be questioned as to its legal validity, or its feasibility, or its morality, etc, but also not its truth or falsity.

For utterances about actions, such as promises, requests, entreaties and commands, truth-value semantics makes no sense.  Instead, we generally need to consider two pragmatic aspects.  The first is uptake, the acceptance of the utterance by the hearer (an aspect first identified by Reid and by Reinach), an acceptance which generally creates a social commitment to execute the action described in the utterance by one or other party to the conversation (speaker or hearer).    Once uptaken, a second pragmatic aspect comes into play:  the power to revoke or retract the social commitment to execute the action.  This revocation power does not necessarily lie with the original speaker; only the recipient of a promise may cancel it, for example, and not the original promiser.  The revocation power also does not necessarily lie with the uptaker, as commands readily indicate.

Why would a computer scientist be interested in such humanistic arcana?  The more tasks we delegate to intelligent machines, the more they need to co-ordinate actions with others of like kind.  Such co-ordination requires conversations comprising utterances over actions, and, for success, these require agreed syntax, semantics and pragmatics.  To give just one example:  the use of intelligent devices by soldiers have made the modern battlefield a place of overwhelming information collection, analysis and communication.  Lots of this communication can be done by intelligent software agents, which is why the US military, inter alia, sponsors research applying the philosophy of language and the  philosophy of argumentation to machine communications.

Meanwhile, the philistine British Government intends to cease funding tertiary education in the arts and the humanities.   Even utilitarians should object to this.

References:

Juergen  Habermas [1984/1981]:   The Theory of Communicative Action:  Volume 1:  Reason and the Rationalization of Society.  London, UK:  Heinemann.   (Translation by T. McCarthy of:  Theorie des Kommunikativen Handelns, Band I,  Handlungsrationalitat und gesellschaftliche Rationalisierung. Suhrkamp, Frankfurt, Germany, 1981.)

Charles  L. Hamblin [1987]:  Imperatives. Oxford, UK:  Basil Blackwell.

P. McBurney and S. Parsons [2007]: Retraction and revocation in agent deliberation dialogs. Argumentation, 21 (3): 269-289.

Adolph Reinach [1913]:  Die apriorischen Grundlagen des bürgerlichen Rechtes.  Jahrbuch für Philosophie und phänomenologische Forschung, 1: 685-847.




On meaning

Over at Normblog, Norm returns to his argument against religion as a human activity that ultimately implies beliefs in the form of propositions.  I have written against this view before – here, and here, and here.  In his latest post, I think Norm makes two errors of reasoning common to western philosophy these last three centuries or so – that of conflating knowledge in general with a specific form of knowledge, namely know-what (knowledge of facts about the world), and that of conflating know-what with a particular representation of it in the form of propositions (statements about the world with truth values).

We can know how to tie our own shoe-laces, for example, and, as knowledge engineers in computer science have learnt these last 50 years, such know-how is not the same as know-what, and is also often very difficult to represent as propositions about the world.  Without explicit representation of the actions, one is forced to associate each action with the propositions that are true before its execution, and those true afterwards, ie, two states, or collections of propositions.  But doing so does not enable us to distinguish different actions having the same pre- and post-states, for example, two different procedures for tying the same shoelace knot.  One is therefore soon forced to explicitly represent actions.  But what exactly are these things, these representations of actions?  They are not statements with truth values; indeed, they are not even statements. And this is just for plain old actions, not even utterances about actions, such as promises and requests and commands, all of which may comprise part of a system of know-how (eg, knowledge of how to steer a crewed sailing ship, or knowledge of the process of launching an ICBM).

Even know-what may not be readily amenable to propositional representation, or at least not to propositions understandable by the human subject having the knowledge:  any propositional representation of the knowledge of the hundreds or thousands of scents distinguishable by an expert perfumier, for instance, would likely have to involve descriptions of chemical molecules in a style and formal language way beyond the knowledge or thinking or scent-memory of the perfumier.  The same conclusion is true with even greater force for the knowledge of non-human beings, such as the keen olfactory sense of most dogs or the navigational abilities of homing pigeons;  I’ve yet to meet a dog that understood a proposition, but dogs retain an ability to recall and distinguish scents despite this inability at propositional representation.   I have written before on different forms of knowledge here.  And if you think all knowledge of geography has to be represented as maps, you should see Rory Stewart’s example recounted here.

Norm ends with:

At bottom, the whole intellectual project founders, in my view, on this logical conundrum: if you really do evacuate religion of all its substantive beliefs, it will be left as meaningful as scraping a stick along a wall, or balancing a marble on your head, or pronouncing a slow ‘drooom’ into a mauve cup; and if religion has more significant meaning than that for its adherents, meaning which really matters to them, this must be because of things religion says about the condition of the universe and their place within it.”

Norm’s  understanding of “meaning” seems only to be know-what; a wider view of meaning throws that final “must” into serious question.  The meaning of scraping a stick along a wall may be the pleasant sound this action leads to, or the pleasure is gives your hand as the stick undulates with the surface of the wall, or the pleasure it gives you to have a hand able hold a stick, or the presence of friends and family doing the same action with you, or that doing this enables you to recall past times, when you were younger perhaps, when you enjoyed doing the same thing, or that your ancestors likely did the same as long there have been walls  and you wish to honor them by repeating the action, or the sense of bliss or ecstasy or contentedness or calm that scraping sticks along walls may induce in you.  The meaning of a stick against a wall for you may even be its complete lack of any ostensible meaning, its complete and utter time-wasting lack of utility, especially for us western moderns in a culture obsessed with achievement, success, progress, time, self-improvement, and bildung.

All of the meanings I’ve listed here apply equally well to religious activities and other rituals, both social and personal, such as prayer and meditation and attending church services.  And I find it hard to believe that someone who follows sport with enthusiasm should appear to insist that all human activities should have meanings to their adherents that entail propositions testable by external observers, as if all our actions were subject to some community test of significance of meaning.   Does the thought that cricket really matters to me necessarily occur because of things cricket says about the condition of the universe and my place within it?  This I doubt.  If it’s not true for cricket, why should it be true for religion? If Norm wants to insist on religion satisfying such a test, then this constraint says more about his paucity of understanding of religious practices and ideas than anything it might say about religion itself.




Antikythera

An orrery is a machine for predicting the movements of heavenly bodies.   The oldest known orrery is the Antikythera Mechanism, created in Greece around 2100 years ago, and rediscovered in 1901 in a shipwreck near the island of  Antikythera (hence its name).   The high-quality and precision nature of its components would indicate that this device was not unique, since the making of high-quality mechanical components is not trivial, and is not usually achieved with just one attempt (something Charles Babbage found, and which delayed his development of computing machinery immensely).

It took until 2006 and the development of x-ray tomography for a plausible theory of the purpose and operations of the Antikythera Mechanism to be proposed (Freeth et al. 2006).   The machine was said to be a physical examplification of  late Greek theories of cosmology, in particular the idea that the motion of a heavenly body could  be modeled by an epicycle – ie, a body traveling around a circle, which is itself moving around some second circle.  This model provided an explanation for the fact that many heavenly bodies appear to move at different speeds at different times of the year, and sometimes even (appear to) move backwards.

There have been two recent developments:  One is the re-creation of the machine (or, rather, an interpretation of it)  using lego components.

The second has arisen from a more careful examination of the details of the mechanism.  According to Marchant (2010), some people now believe that the mechanism examplifies Babylonian, rather than Greek, cosmology.   Babylonian astronomers modeled the movements of heavenly bodies by assuming each body traveled along just one circle, but at two different speeds:  movement in one period of the year being faster than during the other part of the year.

If this second interpretation of the Antikythera Mechanism is correct, then perhaps it was the mechanism itself (or others like it) which gave late Greek astronomers the idea for an epicycle model.   In support of this view is the fact that, apparently, gearing mechanisms and the epicycle model both appeared around the same time, with gears perhaps a little earlier.   So late Greek cosmology (and perhaps late geometry) may have arisen in response to, or at least alongside, practical developments and physical models.   New ideas in computing typically follow the same trajectory – first they exist in real, human-engineered, systems; then, we develop a formal, mathematical theory of them.   Programmable machines, for instance, were invented in the textile industry in the first decade of the 19th century (eg, the Jacquard Loom), but a mathematical theory of programming did not appear until the 1960s.   Likewise, we have had a fully-functioning, scalable, global network enabling multiple, asynchronous, parallel, sequential and interleaved interactions since Arpanet four decades ago, but we still lack a thorough mathematical theory of interaction.

And what have the Babylonians ever done for us?   Apart from giving us our units for measuring of time (divided into 60) and of angles (into 360 degrees)?

References:

T Freeth, Y Bitsakis, X Moussas, JH Seiradaki, A Tselikas, H Mangou, M Zafeiropoulou, R Hadland, D Bate, A Ramsey, M Allen, A Crawley, P Hockley, T Malzbender, D Gelb,W Ambrisco and MG Edmunds [2006]:  Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism.  Nature444 (30):   587-591.  30 November 2006.

J. Marchant [2010]:  Mechanical inspiration.  Nature, 468:  496-498.  25 November 2010.




Bob’s your uncle

Being a colleague of Robert Mugabe greatly increases your chances of an early death, especially in a car accident.      Here’s a list of people who met unexpected ends while working with Bob (showing the year of their death).  No doubt the car accidents are due to chance.

  • Herbert Chitepo (1975), ZANU leader, killed by car bomb in exile in Lusaka.
  • Josiah Tongogara (1979), ZANLA leader, died in a car accident in Mozambique during return from exile.
  • Charles Tazvishaya (aka Lovemore Mawisa) (1986), personal private secretary to Prime Minister Mugabe, survived a gunshot wound to the head inflicted in the bedroom of his house and then died in Parirenyatwa Hospital, Harare, a fortnight later, after his medical drip was detached from the source medication.
  • Maurice Nyagumbo (1989), Minister for Mines, died from ingesting pesticide.
  • Border Gezi (2001), Minister for Gender, Youth and Employment, died in a car accident.
  • Moven Mahachi (2001), Minister of Defence, died in a car accident.
  • Elliot Manyika (2008), Minister Without Portfolio and National Political Commissar for ZANU-PF, died  in a car accident.
  • Susan Tsvangirai (2009), wife of Morgan Tsvangirai, the new Prime Minister in the Government of National Unity, died in a car accident.
  • General Solomon Mujuru (aka Rex Nhongo) (August 2011), former Commander-in-Chief of the Zimbabwe Armed Forces and husband of Vice President Joice Mujuru, died in a house fire which destroyed his farmhouse near Beatrice.