Saturday, December 13, 2014

Structural realism

I'm posting some email exchanges I had with a couple of friends regarding the philosophy of science:

Recently I saw a jogger with a hydration belt. That's something I've seen before. But this time I noticed that the bottled water in her belt was yellow. 

That got me thinking. From a distance, you can't tell if it's yellow fluid in a clear bottle, or clear fluid in a yellow bottle. One of the ambiguities of sensory perception. 

Of course, there are ways of finding out. Empty the bottle. That way you can see if it's the fluid or the bottle that's yellow.

But suppose sensory perception itself (i.e. what we perceive with) is like that? To vary the illustration: when I see color, is that because the world is colorful, or because my lens is tinted (as it were)? 

Ultimately, it's hard to know how we'd detect the difference, since we have no independent standard of comparison. We can't perceive the world apart from our senses, so we can't contrast a sensed world with an unsensed world. 

I agree with you that what we perceive is probably a combination of what our brain/sensory perceptual system contributes along with some objective properties of the external stimulus.

However, the problem I'm discussing is runs deeper. For instance, when I peer through a telescope or microscope, that artificially enhances my natural visual acuity. However, the enhanced data is still filtered back through my eyes, and interpreted by my brain.

Hence, I don't think there's an independent way to tell how much of what I perceive is objective and how much is subjective. 

Even my description of brains and sense organs is deceptively circular, for we use brains to study brains, we use sense organs to study sense organs. But in that event, we never have direct knowledge of we're using to perceive the physical world. Since we always perceive the world with something, we can't say what the prism is like without it. 

And I think that conundrum presents a more serious problem for atheism, with its "blind safecracker," and its lack of divine revelation to correct or corroborate our perceptions. 

i) Science is ultimately based on our sensory perception of the physical world. Depending on the branch of science, this may involve direct observation, or it may be more inferential. 

But the conundrum involves the gap between the sensed object and the unsensed object. All we can ever know about is the sensed object. The unsensed object remains out of reach. We never know what the object is like apart from our sensory perception. 

Some people might say that's a Kantian distinction, but there's nothing uniquely Kantian about it. The distinction between appearance and reality goes back to the Pre-Socratics.

Hence, science can never tell us what the world is really like. 

ii) Secondly, In a way, I agree with Richard Lewontin that once you allow a divine foot in the door, it's hard to draw the line on what might happen. I simply derive a different conclusion. He confuses disapproving with disproving. Because he doesn't like the consequences of a divine foot in the door, he rejects it. But, of course, that doesn't mean there is no divine foot in the door! 

To take an example, critics of mature creation say this would mean we see an image of a supernova that never existed. We see the effect of an illusory cause.

However, I don't find that antecedently objectionable. What if the universe is like a movie set? Take Tombstone. The story begins in 1881. Logically, there's a backstory. But in the world of the movie, you can't go back in time to a period before October 1881. In the world of the movie, nothing happens before October 1881. Everything starts at that point, and continues from that point. 

For all I know, that's what the history of the universe amounts to. It actually begins within an ongoing cosmic narrative. And that would be indistinguishable from a real prehistory. 

I'm not saying that's how it happened. Rather, I'm saying that in the nature of the case, I have no evidence to the contrary, and I don't have any a priori theological objection to that scenario. 

Moving along, it isn't clear to me (from the article) why structuralism is classified as scientific realism rather than antirealism. When it says things like we can't know what nature is intrinsically like, that has more in common with scientific antirealism than realism. Indeed, that denial dovetails with my own position. 

Another complication is that, at best, this is a family of positions, rather than one clear-cut position. Indeed, even that may well be an overly generous characterization. 

It is widely held that the most powerful argument in favour of scientific realism is the no-miracles argument, according to which the success of science would be miraculous if scientific theories were not at least approximately true descriptions of the world. 

That's not a problem for my position. So long as there's a consistent correlation between the proximal stimulus and the distal stimulus, what we perceive can be very different than what the world is really like, yet our scientific theories would still be successful. They don't need to be true descriptions of the world, but true descriptions of the phenomena. For as long as the phenomena track the world in a systematic correlation, phenomenal descriptions will be scientifically reliable. 

For instance, compare the relationship between music and a music score. A music score isn't music. It doesn't resemble music. It's just notation. A code language for representing music. Yet there's a one-to-one correspondence between music and a music score. That's why you can use the score to reconstruct the music.

Same thing with a CD. The encoded information isn't music. But a CD player will translate the digitized data back into music. 

Let's take a comparison. Suppose a medieval physician notices a pattern. He notes a correlation between outbreaks of Bubonic plague and rat infestation. He also notices that plague outbreaks radiate out from port cities. He hypothesizes that rats cause the plague. That the plague originated elsewhere, and was spread by rats on ships. He further theorizes that pest control measures ought to reduce epidemics of Bubonic plague.

Is this a true theory? Yes and no. Rats don't cause the plague. Not directly. Yet we might say his theory tracks the truth. The truth is two steps removed from rats. Rats are carriers of fleas, and fleas are carriers of the bacterium. Of course, he knows nothing about the existence of bacteria.

Yet he's right to notice a correlation between rats and plague. And, considered as a whole/part relation, there's a sense in which rats cause plague, inasmuch as that coarse-grained explanation includes or covers the actual underlying cause.

Since bacteria are undetectable to a medieval physician, he can only go by appearances. But the appearances reveal a consistent correlation. And the appearances are the effects of an underlying cause, even if the cause is imperceptible. 

Scripture attributes some (but not all) pestilence to specific divine judgments. That's not necessarily miraculous in the classical sense of God bypassing natural processes. In many cases it could be a coincidence miracle, whereby God prearranges natural events to produce pestilential hotspots at the right time and place. 

In that case, God is one of the causes of the pestilence. As David Lewis put it, “We think of a cause as something that makes a difference, and the difference it makes must be a difference from what would have happened without it.” 

So it's not reducible to physical causation alone. It's too targeted to be the outcome of nature's automatic setting. So it's not predictable in that respect.

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