Where’s the fish?

A colleague shared with me the link to this Einstein’s riddle.  It looks easy at first, but it actually isn’t.  I’ve tried a couple of different models to solve it, but haven’t figured it out yet.  Something tells me that if I remembered Prolog from my college days, I would have solved it in about 3 minutes.  But I don’t.  So pieces of paper and text files it is.  If that won’t be enough until lunch time today, I’ll start doing something in PHP or Perl…


Update: Solved it!  My initial model of addition wasn’t right. Subtraction worked much better.

The art of the argument

Paul Graham wrote yet another excellent essey – “How to Disagree“.

The web is turning writing into a conversation. Twenty years ago, writers wrote and readers read. The web lets readers respond, and increasingly they do—in comment threads, on forums, and in their own blog posts.
Many who respond to something disagree with it. That’s to be expected. Agreeing tends to motivate people less than disagreeing. And when you agree there’s less to say. You could expand on something the author said, but he has probably already explored the most interesting implications. When you disagree you’re entering territory he may not have explored.

He then proceeds with identifying a hierarchy of disagreements.  In his view, the forms of disagreement are:

  • DH0: Name-calling.
  • DH1: Ad Hominem.
  • DH2: Responding to Tone.
  • DH3: Contradiction.
  • DH4: Counterargument.
  • DH5: Refutation.
  • DH6: Refuting the Central Point.

Paul’s post reminded me of something – a course of formal logic back in college.  One of the things that course covered was a list of fallacies, which are often used in arguments either intentionally or not.  Of course, the complete list of fallacies is much longer and will take more time to memorize and understand.  But, if you wish to win and rule online (and offline) arguments, you should at least get familiar with those.

Paul organizes hist list of disagreement forms into a hierarchy. He says:

Indeed, the disagreement hierarchy forms a kind of pyramid, in the sense that the higher you go the fewer instances you find.

It would be nice to see a similar, hierarchy organization for the longer list of fallacies.   Which ones are the most frequent in online discussions?  Which ones are easier to create and why?  How to recognize and respond to them?

Irony in science or a bad example of Post Hoc

While reading through this excellent website I came across an article about Post Hoc logical fallacy. To freshen your memory, this article describes Post Hoc fallacy as follows:

A Post Hoc is a fallacy with the following form:

1. A occurs before B.
2. Therefore A is the cause of B.

There are also a few examples that help to understand this fallacy. Among these examples there is this one:

Bill purchases a new PowerMac and it works fine for months. He then buys and installs a new piece of software. The next time he starts up his Mac, it freezes. Bill concludes that the software must be the cause of the freeze.

I couldn’t help the smile. In the scope of logic as a science this example perfectly illustrates the point. But in the scope of computer science this quote would be a good example of the opposite. In other words, if you computer worked fine for months and than you installed a new piece of software on it, and it started to freeze – chances are that the software is the cause of problem.

Ironical, isn’t it?

Daily del.icio.us bookmarks

I think that I should spice up a bit these long lists of links. I’ll be adding some comments once in a while for this posts to be more human friendly. Those posts with a lot of links (lik this one) will be split into a introductory part and the full article, so that the main page of the site won’t get too long to scroll.

First group of links has to do with logic programming in Prolog language. Most of these links I found in the reference list in Ovid’s presentation at OSCON. Ovid was talking about ways of integrating Prolog and Perl. The link to his presentation is the first in the list.

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