The Church-Turing Thesis

Jack Copeland gave an interesting lecture on the Church-Turing thesis today. The CT thesis is apparently much misunderstood. Historically, it's the claim that any algorithm can be computed by a Turing machine. But even well-respected philosophers (Jack offered quotes from Fodor, Dreyfus, etc.) sometimes label a much stronger claim - that no information-processing machine can do anything that Turing machines can't - the "Church-Turing thesis", even though neither Church nor Turing ever made such a claim. Note the difference: whereas the real version merely relates Turing machines and algorithms, the stronger version places restrictions on all information processing devices. For example, the latter version implies that no machine can solve the Halting problem. More generally, it can be seen as the claim that hypercomputation is impossible, and that standard (Turing) computation is the pinnacle of information processing. The original Church-Turing thesis made no such grand claims.

An especially extravagant elaboration was made by the Churchlands. They claimed that Turing's results entail that "a Turing machine can display any systematic pattern of responses to the environment whatsoever." Jack pointed out that this was a rather outrageous claim, since some uncomputable 'patterns of response' are perfectly systematic. Consider an environment which presents integer inputs. We can assign each Turing machine a number. Now, here is a perfectly systematic pattern of responses to this environment: the info-processor take the input n, and outputs a '1' if the nth Turing machine halts, and a '0' if it does not halt. But no computer can display this pattern of responses, or else they could solve the Halting problem (which we can prove no computer can do). So there are systematic patterns of response that no computer - i.e. Turing machine - can possibly display.

Backlinks

Via Blogger Buzz, I learn that Blogger now has backlinks (a.k.a. trackback). Whenever you link to one of my posts, a reciprocal "backlink" will automatically appear below my post (just above the comments section), just as soon as Google's blogsearch picks up on it. It's very convenient. I don't know if mine is working yet though, so if anyone cares to test it... ;)

Update: It's working! See here for an example. I especially like how it also creates backlinks when I link to my own previous posts (which I tend to do a lot) -- it keeps my blog well interconnected without my having to manually update the old posts. I highly recommend this feature to other Blogger users out there! (You might find the help page on backlink tags to be useful when editing your template.)

Update 2: There's a bug which means if you view a backlinks-enabled blog in Firefox, you won't be able to select text (e.g. to copy and paste).

Update 3: You can fix this bug by disabling backlinks in your blog's "settings", but then installing this Browservulsel hack to provide backlinks instead.

Upcoming Carnival

The Philosophers' Carnival demands your submission! If that doesn't work, then it asks politely instead. The carnival is to be held on Monday, and we need more entries! If you have a philosophy blog, do send something in. You're also welcome to nominate others' posts using the del.icio.us nominations system.

Counterfactuals and Intuitions

Jonathan Ichikawa has a fascinating post on Tim Williamson's contention that the Gettier intuition rests on a contingent counterfactual. This is a topic Williamson spoke about at the ANU methodology conference I went to a couple of months ago, so I might as well chuck in my two cents.

The problem Williamson tackles is how to formalize the content of the Gettier intuition into logical notation. Here's a plausible first attempt:

(3*) □∀x∀p (GC(x,p) ⊃ (JTB(x,p) & ¬K(x,p)))

That is, "Necessarily, any time someone stands to a proposition as in the Gettier story, he has a case of justified true belief that isn't knowledge."

Williamson objects that the Gettier story is underdetermined in ways that leave it possible (were we to fill in the gaps in a particular way) for us to deny that the agent's belief is justified in that case, from which it follows that (3*) is false. It makes too strong a claim: what we really want to say is not that an agent satisfying the Gettier story must have JTB without knowledge, but that they would be so. It's really a counterfactual claim, Williamson suggests, which we should analyze as follows:

(3) ∃x∃p GC(x,p) □→ ∀x∀p (GC(x,p) ⊃ (JTB(x,p) & ¬K(x,p)))

That is: If it were the case that some x stood to some p as in the Gettier story, then whoever stood to a proposition in the same way would have a justified true belief that isn't knowledge.

The problem with this is that counterfactuals are contingent - depending for their truth on the location of the actual world in modal space - whereas the counterexamples yielded by thought experiments demonstrate conceptual, i.e. necessary, truths. In particular, Williamson claims that if the actual world was 'deviant' in some respect, such that the closest possible world in which the Gettier story obtains is one where the agent's belief is not in fact justified, then the Gettier story would fail to refute the JTB analysis of knowledge.

That's just plain wrong. Gettier-style thought experiments don't depend upon actual-world truth values, or our particular location in modal space. Rather, they speak to the entirety of modal space. So they shouldn't be interpreted as counterfactuals assessed from the actual world. That's not how they work at all.

Jonathan's response came at this from the perspective of truth in fiction. The key idea is that what's true in the Gettier stories is not underdetermined in the crucial respects that lead to the agent having JTB without knowledge. A deviant actual world won't affect what's true in the Gettier story, because implicit truths in fiction are better filled in by something like "collective belief worlds", i.e. what we all believe is actually true, rather than what really is true (possibly unbeknownst to any of us).

My initial reaction to Williamson's suggestion was rather similar, though I didn't see it in terms of fiction. I just thought that we should be assessing the counterfactual in (3) against normal rather than actual conditions, so as to preclude actual-world deviancy from having any effect. This amounts to the same thing as appealing to a 'collective belief worlds' analysis of truth in fiction.

So Williamson's (3) is still too strong, since thought experiments should not be held hostage to our (possibly deviant) location in modal space. I suggested to Williamson (in the "question time" after his talk) that (i) this was a problem; and (ii) we could overcome it by sticking a possibility operator in front of the whole subjunctive conditional:

(3') ◊(∃x∃p GC(x,p) □→ ∀x∀p (GC(x,p) ⊃ (JTB(x,p) & ¬K(x,p))))

That is: There is some possible world (it need not be the actual one) at which the counterfactual expressed in (3) is true.

This is a much weaker claim, since it does not depend upon actual conditions at all, but it nevertheless suffices for refuting the JTB analysis of knowledge. (I can't remember Williamson's exact response, but I think he was worried that my changes upset the logical form of his argument from the Gettier intuition to the refutation of the JTB analysis.) After all, so long as the counterfactual is true at some possible world, and the antecedent "∃x∃p GC(x,p)" is possible, then it follows that the counterexample "∃x∃p(JTB(x,p) & ¬K(x,p))" is true at some possible world also. And thus it is not a necessary truth that all cases of JTB are cases of knowledge.

So Williamson's contention, that the Gettier counterexample is merely contingent, can be refuted without relying on any particular analysis of truth in fiction. After all, it isn't really about fiction at all, but rather, what's possible. The Gettier case shows that it's possible to have JTB without knowledge. The way it shows this is not through a counterfactual anchored to the (possibly deviant) actual world, but rather, the unanchored possibility of such a counterfactual -- a possibility that does not depend upon our particular position in modal space. As such, we get the appropriate result that the success of thought experiments is not contingent on actual-world normalcy. Even if, by some bizarre coincidence, the closest realization of the Gettier story failed to constitute a counterexample to the JTB analysis, others more distant would succeed, and that's all we need for the refutation.

Theory of Mind in Animals

Supposing that some nonhuman animals can think, the question then arises: can they think about thought itself? Given that they have minds, do they recognize this fact? It is by no means guaranteed, for it is possible to possess a property unknowingly. Perhaps animals are limited to thinking about the physical world, so that, whilst capable of simple reasoning about their own behaviour and others’, they lack any conception or awareness of the mental states that underlie this behaviour. The question thus becomes whether animals possess any mentalistic concepts, such as belief or desire, which they attribute to themselves or others, as part of a general ‘theory of mind’. We must be wary not to take a positive answer for granted. Mentalistic attributions come so naturally to human observers that we may be predisposed to assume that other animals share this ability. As Byrne puts it: “we, as normal humans, find it hard to imagine not being able to understand another’s mental viewpoint.”[1] We are masters of the intentional stance,[2] automatically interpreting behaviour as goal-directed, and using this to make inferences about the agent’s beliefs and desires. But despite how easy this seems to us, it is actually quite a cognitive feat, and we cannot assume that evolution will have seen fit to equip other animals with this same ability. Instead, we must look to the empirical evidence for answers.

According to Gallup’s famous “mark test”, you can assess whether an animal is self-aware by whether it can learn to recognize itself in a mirror. In particular, if you secretly mark the animal’s forehead, and it sees this mark in the mirror and responds by touching its own forehead, then this suggests that the animal recognizes itself in the mirror. But this does nothing to show that the animal has knowledge of its own mind. After all, all creatures have some means of distinguishing their own body from those of other animals, and we would not be surprised if an animal touched a mark directly visible on its paw.[3] But a mirror is simply a perceptual tool of a certain kind, allowing creatures to see things that they otherwise might not. In light of this, why should the implications of mirror self-recognition be so different in kind? Granted, it does demonstrate a form of intelligence, or perceptual resourcefulness, for an animal to learn to make use of a mirror for self-exploration. But the mirror test is largely a red-herring so far as research into animal theory of mind is concerned. Passing the mirror test is not sufficient for self-awareness, as explained above. Creatures need not have mastery of mentalistic concepts to recognize themselves. They might identify their body without thereby realizing that the body contains a mind. And neither does the test identify a necessary precondition for self-awareness. In testing visual perceptual flexibility, it disadvantages creatures which favour other sensory modalities such as hearing or olfaction. And an animal might, plausibly, be capable of thinking about its own mental states whilst lacking the perceptual skills required to recognize its body via indirect means. What we really need to test is conceptual, not perceptual, skills.

One promising line of research investigates animals’ self-monitoring of their own mental states. For example, dolphins were trained to distinguish high from low pitched tones, and were rewarded for selecting the correct paddle. As one would expect, they often made mistakes when the tone was close to their discrimination threshold. Interestingly, when an ‘escape’ paddle was introduced – a safe fallback option with no reward or penalty – the dolphins would often select this option in response to tones near their discrimination threshold.[4] A fairly intuitive interpretation would see the dolphin’s “escape” response as signalling its uncertainty as to which of the two other options – “high” or “low” tone – is correct. This interpretation suggests that dolphins can reflect on their own mental states, assessing their subjective confidence in their own judgments, just as humans can. That is, it suggests that dolphins know their own minds.

This conclusion is not assured, however, for deflationary alternative interpretations of the escape response are possible. The metacognitive explanation is second order, i.e. the dolphin’s response expresses a judgment about its own mental states. But it could just as well be a first-order judgment that is solely directed at the external stimulus. Perhaps the dolphin judges that the tone is both high and low, and this ‘cognitive conflict’ – absent any personal recognition of the conflict – causes it to select the escape option.[5] Thus, while these experiments do at least suggest that dolphins have some functionally metacognitive capabilities, being sensitive to the reliability of their own mental states, this does not establish that they possess mentalistic concepts.[6]

But perhaps we are looking in the wrong place. Perhaps second-order thought is more open to experimental verification when directed at the thoughts of others, rather than oneself. Whilst first-personal metacognitive processes might be helpful for regulative purposes, they are not easily distinguished from sub-personal functional equivalents, and the extra information provided by meta-level knowledge of one’s own fallibility seems only moderately useful from an evolutionary perspective. By contrast, the benefit of attributing mental states to other animals is clearly immense, due to the predictive power it provides. Such capabilities are also more open to empirical investigation, as some third-personal mentalistic attributions are comparatively difficult to ‘deflate’.

Tactical deception is an appealing candidate behaviour for second-order intentional interpretation. These involve cases whereby an animal achieves their goal by causing another animal to obtain a false belief. Byrne describes an example wherein a young baboon named Paul found an adult, Mel, who had just dug up a corm, and subsequently fooled his mother into chasing his rival away:

“[Paul] looked around, seeing no other baboon, and screamed loudly. His mother, who was higher ranking than Mel, ran into view grunting aggressively and immediately pursued Mel. When they had both left the immediate area, Paul ate the corm.”[7]

Despite their appeal, such anecdotes provide unreliable evidence for intentional deception. Paul’s behaviour can be explained by his previously learning the correlation between screaming in certain circumstances and thereby obtaining the food reward. Or, more generously, we might even grant that he recognized that screaming would cause his mother to appear and chase off Mel. But neither of these interpretations require that Paul understands his mother has a mind, so we cannot be sure that his intention was to evoke her false belief.

More generally, we are faced with the problem of how to empirically distinguish first-order from second-order intentionality. Given that any case of tactical deception in animals will be instrumental to obtaining some behavioural output from the target of deception, we might plausibly hold that the deceiver merely intends to provoke this behaviour, rather than the false belief that underlies the behaviour.[8] The question then arises how the animal obtained the means-ends belief that his deceptive act would cause the desired behaviour. There seem two plausible candidates: either the animal has learnt from past experience, or else it has some rudimentary understanding of the causal processes underlying behaviour – i.e. a theory of mind – from which it can make successful predictions. Byrne claims that tactical deception has been observed in great ape populations that are under continuous observation, which allows us to rule out previous trial-and-error learning, and thus provides strong evidence for mentalism in these species.[9] Granted, it is possible for goal-achieving novel behaviours to arise through lucky coincidence, but as Dennett points out, once a broad enough range of examples start to pile up, “the claim that it is all just lucky coincidence… becomes the more extravagant hypothesis.”[10]

So far we’ve focused on general evidence, but it is also worth considering the specific abilities that a theory of mind might involve. The most fundamental component is perhaps an understanding of goal-directed behaviour, whereby one recognizes that other creatures are agents whose actions aim at achieving particular goals. Premack’s experiments suggest that chimpanzees are capable of inferring the goal of an actor’s behaviour – correctly selecting the photograph of a ‘solution’ to a videotaped actor’s ‘problems’ – when three year old humans cannot; though these results are controversial.[11] A more advanced step is to recognize that others can have different beliefs from oneself. Humans typically develop this ability at around the age of four, but it isn’t clear whether any other animals can do the same. For example, Cheney and Seyfarth have found that monkey alarm calls are insensitive to the knowledge or ignorance of their audience.[12] However, some chimps can learn to discriminate between trainers that were or were not present to perceive a critical event – a capacity related to recognition of others’ ignorance.[13] We may further ask whether animals are capable of tracking what others perceive. Apes can use the target’s bodily orientation to judge whether to send a visual signal, and some show evidence of understanding the specific importance of eyes in visual perception.[14] While some such results might merely show that apes can use direction of gaze as behavioural cue, language-trained chimpanzees responded correctly to the question “what’s that?” when asked for the first time without pointing, with the trainer instead merely looking at the target. Whiten suggests that this “reinforces the conclusion that chimpanzees do in fact see visual attention as ‘about’ something.”[15] This would seem to constitute a rudimentary form of second-order intentionality.

In sum, it isn’t entirely clear whether any non-human animals have an understanding of minds. There’s certainly scant evidence that they have the rich conceptual understanding that humans do. But some of the more advanced animals might at least exhibit important precursors to a theory of mind. Dolphin behaviour is sensitive to their own uncertainty, even if we cannot be sure that they are aware of this themselves. There is some evidence that apes have some of the core capabilities that amount to a theory of mind, including an understanding of others’ goal-directed behaviour, visual perception, and possibly ignorance. Anecdotes relating tactical deception are especially enticing, though open to deflationary interpretation if not found under controlled conditions. Further research is required to reinforce and build upon these initial successes – or expose their limitations.

Bibliography

Bennett, J. (1991) ‘How to Read Minds in Behaviour’ in A. Whiten (ed.), Natural Theories of Mind. Oxford: B. Blackwell.

Browne, D. (2004) ‘Do Dolphins Know Their Own Minds?’ Biology and Philosophy 19: 633-653.

Byrne, R. (1995) The Thinking Ape. Oxford: Oxford University Press.

Cheney, D. and Seyfarth, R. (1990) How Monkeys See the World. Chicago: University of Chicago Press.

Dennett, D. (1987) The Intentional Stance. Cambridge, Mass.: MIT Press.

Premack, D. (1988) ‘‘Does the chimpanzee have a theory of mind?’ revisited’ in R. Byrne and A. Whiten (eds.) Machiavellian Intelligence. Oxford: Oxford University Press.

Tomasello, M. and Call, J. (1997) Primate Cognition. New York: Oxford University Press.

Whiten, A. (1997) ‘The Machiavellian Mindreader’ in A. Whiten and R. Byrne (eds.) Machiavellian Intelligence II. Cambridge: Cambridge University Press.

---

[1] Byrne (1995), p.109.

[2] See Dennett (1987).

[3] Derek Browne, lectures; Tomasello & Call (1997), p.337.

[4] Browne (2004), p.641.

[5] Ibid, p.647.

[6] Ibid, p.651.

[7] Byrne (1995), p.124.

[8] Bennett (1991), p.104.

[9] Byrne (1995), p.133.

[10] Dennett (1987), p.251.

[11] Premack (1988), p.176. But cf. Tomasello & Call (1997), pp.319-322.

[12] Cheney and Seyfarth (1990), pp.219-222.

[13] Whiten (1997), p.161, describes experiments by Povenelli to this effect.

[14] Tomasello & Call (1997), p.340.

[15] Whiten (1997), p.165.

The Thinking Man's Tory

TPM have a fascinating interview with British politician and philosopher Oliver Letwin. I wish we had politicians like that here in New Zealand. Consider his remarks about social justice:

I think the main question we need to be addressing is how we can have a society in which people grow up to be the kind of people that we would all like to be. That isn't the way it's often put, but it's my view of what it means to live in a socially just society. To my mind, something has gone very wrong – so we're doing a great social injustice – if there are people growing up to be the kind of people we wouldn't like to be: people who find themselves with chaotic lifestyles which they can't control and which drive them to despair and suicide; people who are oppressed by a lack of ability to control their world and deal with it; people who are deprived of culturally rich existence: all these things seem to me profound social injustices.

Some of them have to do with material prosperity, although that's never a guarantee of getting where I want people to be able to get to; nor is its absence a guarantee of not being able to get people where I want people to be able to get to. There are relationships, but it isn't the case that they should be conceived as a sort of mechanical operation for making sure that everybody has enough money, or for making sure that nobody is attacked by a burglar. It's something much deeper than either of those.

More specifically:

I think there is at the moment a paradox that certain kinds of activity where it would be better if they were freer are more constrained; and other kinds of things where it would better if there were more social support or where social solidarity has been left to decline. For example, we live in a society where there is a huge aversion to risk. There is a colossal amount of regulation designed to minimise risk, I think to an extent which is impeding excellence, exuberance, cultural richness and so on. On the other side, people are growing up in circumstances where they are cruelly deprived of the emotional support that a human being needs in order to live the kind of life that many of us want to lead. This is a particularly intrusive state in some respects and a particularly thin society in other respects.

These are remarkably respectable ideals, especially for a conservative. (I'm used to just hearing them demand tax cuts and rail against gays.) Though he's a bit thin on details, so maybe he'd implement these ideals in a less agreeable fashion. Regardless, it's nice to hear a conservative talking about human well-being for once -- I was beginning to think it was an exclusively left-wing concern. It would be nice if these concerns would permeate the broader public discourse, focusing our attention on the crucial question of how to realise our shared values, i.e. of enabling humanity to lead flourishing lives. This is the challenge for politics, but it's so easily lost in the daily bustle and scandals of partisan politicking.

He also makes a nice point about how philosophy can be important for raising the level of political discourse:

As I see it, the biggest single problem of democracy in Britain today is the level of political discourse rather than the substance of the positions taken... I don't think this is unique to philosophy, but I think that any serious immersion in a serious academic discipline leads people to learn habits of thought that tend to raise levels of discourse. Philosophy is perhaps particularly well adapted to that because it is about thinking about matters of great complexity. That's a particularly good thing for talking about politics in a dispassionate, rational, careful fashion, which helps. It doesn't get the whole way to any answer, but it helps.

Which is Worse: selective or blanket harms?

I don't really have much to add beyond the title question. Here's the context: Bill Bennett counters claims that the ethics of abortion should be decided on the basis of its social consequences, by pointing out that selective forced abortion of all black babies might have the beneficial consequence of reducing crime rates, but is nevertheless quite obviously immoral. Upon hearing this, lots of people get upset and accuse Bennett of racism, against which Jeremy Pierce ably defends him. I'm not really interested in any of that. What I am intrigued by is the following comment that Jeremy makes along the way: "[Bennett] could have made it raceless and just had every fetus being killed regardless of race, but that wouldn't have been as bad a case, and he wanted it to be very bad." Quick survey: who thinks the italicized claim is true?

It strikes me as straightforwardly false, but maybe that's just my consequentialist intuitions showing themselves. The argument is pretty straightforward: Harm is bad. More harm is worse. So it's worse to harm absolutely everyone than it is to selectively harm some particular group and spare others. (Of course, both cases are very bad! It's just that the blanket case is even worse.) In the case of universal forced abortions, you've got all the harms imposed on black people in the selective case and more. Given that there are additional harms, and no compensating benefits, how could this possibly be better?

It seems like such a view would have to rest upon taking equality of group welfare to be intrinsically valuable -- which I think is morally questionable. But if anyone can offer any better arguments for Jeremy's claim, I'd be very curious to hear it...

Religious Immunity

This is an odd remark:

the left, to its discredit, frequently dismisses the views of conservative opponents on, for example, abortion, church-state separation, or feminism as irrational bigotry, when the conclusions of most people who hold such views stem from deeply held, and morally reasoned, religious convictions.

Surely "irrational bigotry" and "deeply held religious convictions" are not mutually exclusive categories. The mere fact that you believe something fervently by no means guarantees that you are right to do so. Yet common rhetoric and discourse would have us believe otherwise. To say that a view derives from one's religious convictions is to mark it as off-limits, immune from rational criticism. It's considered somehow "offensive" to question religious beliefs, or to so much as consider the possibility that they might not be well-grounded or rationally defensible. Needless to say, this isn't a good thing for reasoned discourse.

Granted, the quote from Alan Wolfe above isn't so explicitly absurd, as it does sneak in the clause: "and morally reasoned". Assuming this means something like "well reasoned", then it really is mutually exclusive with "irrational bigotry". But then it's this "morally reasoned" clause which is doing all the work, so why mention the "deeply held religious convictions" at all? This window dressing carries no rational weight, the only purpose for it that I can see is the pernicious rhetorical intimidation. You know, the implication that it would be "intolerant" and "offensive" for you to criticise any position that derives from "deeply held" religious beliefs. It's a clear example of passive-aggressive bullying tactics.

Anyway, if we ignore this rhetoric and focus on the substance of Wolfe's remark, all he's done is assert that most religiously derived moral views are "morally [well] reasoned". Is this true? It doesn't seem obvious to me. Conservatives tend to value obedience to authority over freethought, and "obedience to divine rules" seems to be their standard conception of morality. When your ethical understanding is limited to something so arbitrary as "do whatever [the minister says] the Bible says", I really don't think that's a far cry from "irrational bigotry" at all. The fact that religious conservatives hold to their views with dogmatic fervour is no defence. Quite the opposite in fact. These conservatives are irrational precisely because their views are based on "deeply held religious convictions", rather than reflective thought. Wolfe's attempt to twist this vice into a virtue is simply bizarre.

Truth and Lies

What is a lie? It's not really the opposite of telling the truth, for one can be honestly mistaken in speaking falsehoods. An initial modification would be to say that lying is telling falsehoods on purpose. But do lies actually need to be false? I'm not sure if the concept is clear on this point. I would have thought that actual falsehood is unnecessary: whether a statement is a lie depends solely on the intentions of the speaker. But sometimes people seem to treat the concept differently, and I guess it does sound a little strange to say that a true statement could be a lie.

Consider the following case: Weevil believes the Earth is flat. But, nasty little bugger that he is, he wants Columbus to sail over the edge and fall into the abyss. So when Columbus asks him whether the Earth is flat, Weevil says it isn't. He was intending to deceive, but accidentally ended up telling the truth. Did Weevil lie?

Setting the factive issue aside, intending to tell a falsehood is still insufficient for lying. After all, one might be telling a story or a joke, or engaging in hyperbole or sarcasm. The speaker's higher-order intentions clearly matter here. The speaker must intend to deceive the audience into mistaking what he truly intends, thus leaving them vulnerable to false belief formation. Anyway, that's all pretty straightforward stuff. I'm mainly just curious to hear whether people think lies have to be actually false, or if the intent to deceive suffices.

What if the speaker 'slips' and accidentally says what they believe to be true, when they meant to say something false. Although they acted with intent to deceive, it seems odd to call the slip a 'lie'! So I don't think we should be too subjectivist here. Lying involves more than just deceptive intent; I think the liar must also say something that they genuinely believe is false. If they slip up, then they failed in their attempts to lie. They intended to lie, but ended up speaking honestly by mistake. This seems possible. The question now becomes: how far does this objectivity extend? Is it possible to think you're lying when in fact you're not, just because what you think is false actually happens to be true? Or are actual truth values strictly irrelevant, so that there's nothing problematic about true lies?

May Spammers Burn in Hell

Holy crap, I awoke to find 200 spam comments scattered around my blog today! There's no easy way for me to get rid of them all. I'll at least clear up the main page though. I've tried adding "word verification" to the comments form, but the hack apparently doesn't work perfectly on Internet Explorer (if you have any problems, email me). I might end up having to change back to old fashioned Blogger comments. Anything to stop the flood of spam!

Update: It turns out the spammers were using the old Blogger pop-up comments link I'd left there before. I've now removed that link, so now the only way to comment is via the post-page comment form. Hopefully that'll be enough to keep the spammers out. (If not, I'll have to resort to old Blogger comments + word verification.)