Friday, March 10, 2006

The teleological argument revisited

This was posted by Bill Vallicella on his blog:


Are Biological Functions Observer-Relative?

The following three positions need to be distinguished:

1. There is design in nature, and a complete account of it is impossible without recourse to a cosmic designer such as God.
2. There is intrinsic design in nature, and it is wholly explainable in naturalistic terms.
3. There is no intrinsic design in nature: all features that exhibit design, purpose, function are observer-relative, and the only observers are themselves denizens of the natural world.

Malcolm Pollack and others in several comment threads have come out in favor of (2). (2), however, involves the claim that there is intrinsic design in nature, a claim that is far from obvious, and is arguably inconsistent with Darwinism. So this is something we need to discuss. The following considerations will be based on passages from John Searle's The Construction of Social Reality (The Free Press, 1995). We will take a preliminary look at the contention that there are no intrinsic design features in nature, equivalently, that biological functions are observer-relative.

1. Some features of a thing are intrinsic to it. The mass of an object, for example, is intrinsic to it. What that means, roughly, is that it is not in virtue of a relation to anything else that a massive thing has its mass. By contrast, weight is not intrinsic since the weight of an object depends on the gravitational field it is in: a thing of invariant mass has different weights on the earth and on the moon. The relevant principle here is Newton's Second Law: F=ma. Weight is a force.

Suppose the object is a screwdriver. Its being a screwdriver is not intrinsic but relational: it is only in relation to an observer or user or fabricator that a screwdriver is a screwdriver. Of course, nothing can be a screwdriver unless it has certain intrinsic properties that fit it to play this functional role: one cannot make a screwdriver out of ice or spaghetti. Not even an Eskimo or an Italian could do it. But the property of being a screwdriver is not intrinsic to the object. It is an observer-relative feature.

The property of being a screwdriver is epistemically objective but ontologically subjective. (p. 10) Thus it is objectively true that the tool in my hand is a screwdriver, but its being a screwdriver necessarily involves a reference to a subject who uses it as such.

Here is a rough-and-ready test to determine whether a property is intrinsic or observer-relative: Could the property exist if there had never been any human beings or other sorts of sentient beings? (p. 11) The property of being a screwdriver could not exist (be instantiated) in a world in which there were no sentient beings. This ought to be obvious. A screwdriver is an artifact designed for the purpose of inserting screws by beings who make plans and have purposes. In a world without such purposive beings there would be no tools of any kind. There might be rocks, ponds, fires, and forests, but no paperweights, swimming holes, heaters, or fuel sources.

2. Searle's point about functions is that they are never intrinsic but always observer-relative. Functions are assigned or imposed by us. A burro (my example) is not intrinsically a beast of burden but is susceptible to having that functional role imposed on it. Or else we fabricate a mechanical 'burro' to suit our purposes.

There are no functions in the natural world: "nature knows nothing of functions." (14). Hearts occur in nature, and it is an observer-independent fact that they cause blood to course through the bodies that house them. But the function of the heart to pump blood is not intrinsic to nature.

One consideration in support of this view is that things in nature cannot be said to either fail or succeed in exercising their function. You cannot say of a piece of metal in nature that it failed or succeeded since there is no job or function that it was supposed to perform. But one can say of a metal rivet that it failed or succeeded. ('The main rivet failed and that triggered a series of events that led to the collapse of the bridge.') Normative talk is now appropriate. Only things having functions can malfunction. Depending on its size and shape and weight, a rock may make a good or bad weapon once we assign it the weapon function. But a rock in nature is neither good nor bad since there is nothing that a rock in nature is FOR. There are no weapons or paperweights or door stops in nature.

As Searle puts it, "functions are never intrinsic to the physics of any phenomenon but are assigned from outside by conscious observers and users." (14) But wasn't the function of the heart, namely, to pump blood, discovered? Now if a function is discovered, how can it be "assigned from the outside"?

Although it is true to say that we discover the functions of organs and the like, "the discovery of a natural function can only take place within a set of prior assignments of value (including purposes, teleology, and other functions)." (15) The natural facts are exhausted by the causal facts. The functionality of the heart is something we add to the natural facts. So although one does discover how the heart works -- its mechanism -- one does not discover any teleology. Searle:

It is because we take it for granted in biology that life and survival are values that we can discover that the function of the heart is to pump blood. If we thought that the most important value in the world was to glorify God by making thumping noises, then the function of the heart would be to make a thumping noise, and the noisier heart would be the better heart. (15).

3. Searle thinks that Darwinism supports his contention that functions are never intrinsic, but always observer-relative:

One of Darwin's greatest achievements was to drive teleology out of the account of the origin of species. On the Darwinian account, evolution occurs by way of blind, brute, natural forces. There is no intrinsic purpose whatever to the origin and survival of biological species. (16)

Searle could draw on the authority of experts like Ernst Mayr who also insist that Darwinian theory results in the expulsion of Aristotelian final causes.


1. Before I get to my main point, it seems to me that Searle's distinction between feature and function is generally valid, but it needs to be refined.

i) Although a screwdriver can function as either a murder weapon or else a tool for turning screws, surely the former function is arbitrary compared to the latter.

ii) Likewise, although a donkey can function as a beast of burden, and a heart can function as a pump, surely the former function is arbitrary compared to the latter.

So this distinction (between arbitrary and inarbitrary) holds true for natural objects as well as artifacts.

iii) There are also degrees of arbitariness. A fly-swatter, newspaper, and stick of dynamite can all be used to kill houseflies, but due to their intrinsic features, the fly-swatter is more efficient in performing this function than a newspaper, while a newspaper is more efficient at this function than a stick of dynamite.

vi) How do we explicate these distinctions? What is the differential factor?

Is it not design?

The reason a screwdriver has "certain intrinsic properties that fit it to play this functional role" is that it was designed to have these intrinsic properties in order to perform that very function.

By contrast, co-opting a screwdriver as a murder weapon is a case of merely assigning or imposing an observer-dependent function on the object.

Likewise, co-oping a donkey to serve as a beast of burden is a case of merely (re-)assigning or imposing an observer-dependent function on the object in a way that the blood-pumping "function" of a heart is not.

There's also the matter of artificial breeding, in which we don't merely co-opt a wild animal for domestic use, but redesign it to our own specifications.

So to say that biological functions are observer-relative is not equivalent at all to saying that natural objects lack intrinsic design features.

Although functions are observer-dependent while features are intrinsic, yet, in the case of artifacts, the intrinsic features are also design features; hence, feature and function are, in that artifactual instance, equivalent, rather than their absence.

What about bioorganisms rather than artifacts?

2. Which brings me to my main point.

By denying that function is an objective property of organisms, Searle is apparently attempting to undercut the teleological argument and establish naturalistic evolution.

But couldn't his argument be upended?

On the one hand, to suggest that limbs and organs have no intrinsic function, such that using eyeballs to play a game of marbles is no more or less arbitrary that using the eye to see with, is a reductio ad absurdum of naturalistic evolution and a secular outlook.

Yet Searle does have a point. Function is a relational property.

But if there is no sentient being or artificer to account for these properties, but only the non-directive process of mutation, natural selection, or whatever the favored mechanism of naturalistic evolution, then we're left with an absurd conclusion which is, nevertheless, entailed by a true premise.

3. The only way out is the recourse to a Creator who assigns all biological functions to all organisms by the way in which he designs them. That is why some features are preadapted to perform specific functions. They have design features with specified functions.

This, then, would be an argument, not merely for inferring a divinely assigned function from a few paradigm-cases of apparent design like the bacterial Flagellum, but to any biological function whatsoever.

4. This would also revive and fortify the traditional version of the teleological argument as an argument from analogy with human artifacts, viz. watch/watchmaker.

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