May 20, 2009

The Break of the Curveball

Posted in Baseball, Law, Science, Worldview tagged , , , , at 12:34 pm by Andrew

When delving into presuppositional arguments (or the Argument from Reason, or other claims by Christians in support of mind-brain dualism), I’ll often point out that the brain we have is not cognitively reliable in precisely the sort of ways you would expect given evolution — e.g., things like Alien Hand Syndrome, optical illusions, and so on.

Thanks to Stephanie, I’ve now found the single best illustration I’ve ever seen of the way in which our brain can be fooled: the break of the curveball in baseball.

Those of us who threw curveballs know the fundamental dilemma: a classic, Blylevenesque “12-to-6” curveball appears to break much more sharply than it actually does. Part of the work of the “break” is accomplished by downward spin, and part of it is accomplished by optical illusion.

If you follow this link, you’ll see the optical illusion portion of the curveball’s break illustrated vividly. Watch the path of the spinning ball, and you can see that it travels in a straight line. Shift your focus to the blue spot, and the ball seems to be curving away from you at a drastic angle. It’s eerie!

The authors conclude:

In baseball, a curveball creates a physical effect and a perceptual puzzle. The physical effect (the curve) arises because the ball’s rotation leads to a deflection in the ball’s path. The perceptual puzzle arises because the deflection is actually gradual but is often perceived as an abrupt change in direction (the break). Our illusions suggest that the perceived “break” may be caused by the transition from the central visual system to the peripheral visual system. Like a curveball, the spinning disks in the illusions appear to abruptly change direction when an observer switches from foveal to peripheral viewing.

Just another datapoint in support of the view that our cognitive faculties are the unreliable, cobbled-together product of millions of years of evolution of the physical brain, and not some disembodied mind crafted by an almighty God.

Presuppositionalism, Part 5 (Or: What Counts As a Worldview?)

Posted in Answering Apologists, Atheism, Worldview tagged , , , , , at 9:55 am by Andrew

Continuing the discussion of presuppositionalist arguments for Christianity, one common thread seems to be that Christianity as a worldview better “explains” certain features of the world than does a naturalist/physicalist worldview. While I have previously challenged the dichotomy inherent in the argument — one need not be a naturalist/physicalist in the strong sense to be an atheist, of course — I also challenge the premise itself.

So let’s start with first principles: what does it mean to give an “explanation” for something? One need not accept Kant’s epistemology to nevertheless recognize the distinction Kant drew between (1) the analytic and (2) the synthetic. An analytic explanation is one where the explanation is derived entirely from the predicate of the proposition; put more simply, when I say, “That object is a triangle, because it has three sides,” I have given an analytic explanation. I haven’t told you anything about the triangle that you didn’t already know, because the definition of a triangle is that it has three sides.

On the other hand, if I say that object is green because it was painted with watercolors, I have given you a synthetic explanation; that is, one in which the proposition contains more information than is simply found in the predicate.

Now, to the point: it seems to me that only a synthetic proposition truly counts as an ‘explanation.’ If I say that the grass is green because it has a “green-producing nature,” that isn’t really an explanation. Ultimately I’ve told you that the grass is green because the grass is green. An explanation doesn’t just tell us that something exists; it tells us how.

And this is the problem I have with presuppositional apologetics and comparative worldview arguments. It’s just not an explanation in the synthetic sense to say “God did it.” It doesn’t tell us ‘how,’ it just gives us another name for the problem.

So my question to those of you who favor those sorts of comparative “worldview” arguments: what’s your criterion/-ia for what counts as an “explanation?”