Saturday, December 26, 2009

Eastern APA Session: New Waves in Philosophy of Mathematics

On the first night of the APA in New York City I will be participating in a session designed to unveil the book New Waves in the Philosophy of Mathematics. We are scheduled for Sunday, December 27 from 6:30 to 9:30 pm (GI-8: Society for Realist/Antirealist Discussion). Perhaps not the ideal time, but we will have papers by Otavio Bueno, Oystein Linnebo, Roy Cook, Agustin Rayo and me. Come by to hear about this great volume!

Note: This marks the 100th post on this blog. Thanks to everyone who checks in or links to Honest Toil!

Thursday, December 17, 2009

Dark Matter Rumors (cont.)

The results that prompted the rumors noted in an earlier post have now been unveiled. They involve the detection of Weakly Interacting Massive Particles (WIMPs) which are predicted by some theories of dark matter. The group has provided a helpful two-page summary, with the key paragraph:
In this new data set there are indeed 2 events seen with characteristics consistent with those expected from WIMPs. However, there is also a chance that both events could be due to background particles. Scientists have a strict set of criteria for determining whether a new discovery has been made, in essence that the ratio of signal to background events must be large enough that there is no reasonable doubt. Typically there must be less than one chance in a thousand of the signal being due to background. In this case, a signal of about 5 events would have met those criteria. We estimate that there is about a one in four chance to have seen two backgrounds events, so we can make no claim to have discovered WIMPs. Instead we say that the rate of WIMP interactions with nuclei must be less than a particular value that depends on the mass of the WIMP. The numerical values obtained for these interaction rates from this data set are more stringent than those obtained from previous data for most WIMP masses predicted by theories. Such upper limits are still quite valuable in eliminating a number of theories that might explain dark matter. (emphasis added)
So, Bryan's prediction was correct! Now if only the scientists would tell us what "reasonable doubt" amounts to ...

A Universal Pattern for Insurgents?

From this week's Nature:
The researchers collected data on the timing of attacks and number of casualties from more than 54,000 events across nine insurgent wars, including those fought in Iraq between 2003 and 2008 and in Sierra Leone between 1994 and 2003. By plotting the distribution of the frequency and size of events, the team found that insurgent wars follow an approximate power law, in which the frequency of attacks decreases with increasing attack size to the power of 2.5. That means that for any insurgent war, an attack with 10 casualties is 316 times more likely to occur than one with 100 casualties (316 is 10 to the power of 2.5).


To explain what was driving this common pattern, the researchers created a mathematical model that assumes that insurgent groups form and fragment when they sense danger, and strike in well-timed bursts to maximize their media exposure. The model gave results that resembled the power-law distribution of actual attacks.
This all seems a bit too easy, although I must admit I have not delved into the details of the actual model. I'm also a bit wary of the predictive power of the model, as with "He is now working to predict how the insurgency in Afghanistan might respond to the influx of foreign troops recently announced by US President Barack Obama". But at least this is yet one more case of a purported mathematical explanation in science.

Sunday, December 13, 2009

Dark Matter Rumors Persist

Philosophers interested in tracking how scientists argue for the existence of novel entities might want to stay tuned this week. Rumors of a big announcement, centered largely around the blog Resonances and this post, continue.

Thursday, December 10, 2009

The Popularity of Nominalism

One of the surprises in the recently unveiled results of the PhilPapers Survey of philosophers is the popularity of nominalism:

Target responses

Abstract objects: Platonism or nominalism?

Accept or lean toward: Platonism 366 / 931 (39.3%)
Accept or lean toward: nominalism 351 / 931 (37.7%)
Other 214 / 931 (22.9%)

All responses

Abstract objects: Platonism or nominalism?

Accept or lean toward: nominalism 1454 / 3226 (45%)
Accept or lean toward: Platonism 1016 / 3226 (31.4%)
Other 756 / 3226 (23.4%)

That is, 45% of all the respondents tend towards nominalism. But when we look at people who list an AOS as philosophy of mathematics, the numbers switch:

AOS: Philosophy of mathematics

Abstract objects: Platonism or nominalism?

Accept or lean toward: Platonism 50 / 102 (49%)
Accept or lean toward: nominalism 30 / 102 (29.4%)
Other 22 / 102 (21.5%)

AOS: Logic or Philosophy of Logic

Abstract objects: Platonism or nominalism?

Accept or lean toward: Platonism 112 / 264 (42.4%)
Accept or lean toward: nominalism 96 / 264 (36.3%)
Other 56 / 264 (21.2%)

Does this mean that people outside of philosophy of mathematics don't care what we think, or is it just that our arguments for platonism aren't very good?