Notes on Draper's Article on Behe's Design Argument, Part 4: Behe's Revision
In the last installment, we saw that there are two serious problems for Behe's key claim that some biochemical systems are irreducibly very complex: (i) Behe fails to demonstrate that his example systems in Darwin's Black Box are irreducibly very complex, and (ii) a number of scientists (e.g., cell biologist Kenneth Miller and biochemist David W. Ussery) have given excellent evidence to show that his examples aren't irreducibly complex. However, Draper points out that Behe has responded to this criticism by (in effect) revising his account of irreducibly complex systems. To see how, we’ll need to give a slightly more precise formulation of Behe’s original account of that notion. Recall that his original account defined irreducible complexity as a system "composed of several well-matched, interacting parts that contribute to the basic function, wherein removal of any of the parts causes the system to effectively cease functioning". Thus, Behe's original account of irreducible complexity (henceforth 'IC1') can be expressed in terms of three clauses:
(IC1) A system S is irreducibly complex if and only if:
(i) S is composed of several interacting parts
(ii) S's parts are well-matched
(iii) removal of one or more of S's parts would cause S to cease functioning
Now in response to Ussery's criticisms of Behe's examples of irreducibly complex systems (e.g., Ussery's point that bacterial flagella can perform their function with less than the 40 parts in its system that Behe claimed were essential to its functioning), Behe replies:
"some systems may have parts that are necessary for a function, plus other parts that, while useful, are not absolutely required. Although one can remove the radio from a car and the car will still work, one can't remove the battery or some other parts and have a working car."
(As Draper points out, Behe's analogy isn't quite apt, since a radio isn't a part of a car's primary function. However, Draper helps Behe out by replacing his example of a radio with that of a set of tires. Since tires aren't required for a car to drive, but do enhance its function, we have an apt illustration of Behe's point.)
Two initial remarks concerning Behe's reply to Ussery are in order. First, Behe's response tacitly concedes that Ussery is right, and thus that the bacterial flagellum fails to satisfy Behe's original definition of irreducible complexity (i.e., IC1). Second, and more to the main point in our discussion here, it tacitly replaces IC1 with a new definition of irreducible complexity -- call it 'IC2':
(IC2) A system S is irreducibly complex if and only if:
(i) S is composed of several interacting parts
(ii) S's parts are well-matched
(iii') A subset x of S's parts are such that removal of one or more of x's parts would cause S to cease functioning
The most important thing to notice about IC2 is that clause (iii) of IC1 has dropped out, and with it, its crucial implication that an irreducibly complex system requires all of its parts to function. In its place is a new clause -- clause (iii') -- which only entails the weaker claim that an irreducibly complex system requires a subset of its parts to function. Thus, unlike IC1, IC2 allows a system to count as irreducibly complex even if it has parts that aren't essential to its function.
Thus, with his revised account of irreducible complexity (IC2) in hand, we can put Behe's reply to Ussery as follows: granted, the point about the bacterial flagellum not being irreducibly complex, while strictly speaking correct, doesn't defeat the fundamental point that it contains a subset of parts, each of which must be present from the get-go for it to function at all. But systems like that -- systems that have at least a portion that is irreducibly complex -- can't evolve.
What to make of Behe's new definition of irreducible complexity? If you've been following the earlier posts, you might already see the problem with Behe's reply. For as we have seen in earlier installments, Behe allows that evolution can create simple irreducibly complex systems via indirect evolutionary pathways, and it that it can create reducibly complex systems via direct evolutionary pathways. But if so, then Behe has left open the very real possibility that his example systems have evolved via a two-staged combination of evolutionary pathways: an indirect pathway to create a simple yet irreducibly complex system in the first stage, and then a direct pathway to make that system very complex in the second stage. But such systems satisfy his revised account of irreducibly complex systems (i.e., IC2): systems containing both reducible complexity and an irreducibly complex (in the IC1 sense of 'irreducibly complex') core.
Now one might reply on behalf of Behe that although this sort of two-stage evolutionary process could produce irreducibly complex systems (in the IC2 sense) where the core set of interdependent parts is very simple, it can't account for Behe's example systems (e.g., the bacterial flagellum). For the core set of interdependent parts in those systems are very complex, and thus couldn't have evolved via indirect evolutionary pathways. But this reply won't work. For recall our discussion from the last installment. There, we saw Draper's point that Behe failed to show that his example systems are irreducibly very complex. For when Behe gets around to that task in Part II of his book, he only establishes examples of systems that are irreducibly complex and examples that are very complex. But showing those things is of course crucially different from showing what he needs to show here, viz, that at least some of his examples are irreducibly very complex.
But the problems with Behe's argument don't end here. For as Draper goes on to argue at the end of his article, Behe's arguments against simple direct and indirect evolutionary pathways to irreducibly very complex systems have very large holes in them. We'll wrap up our discussion of Draper's article by discussing these points in the next post or two.
(IC1) A system S is irreducibly complex if and only if:
(i) S is composed of several interacting parts
(ii) S's parts are well-matched
(iii) removal of one or more of S's parts would cause S to cease functioning
Now in response to Ussery's criticisms of Behe's examples of irreducibly complex systems (e.g., Ussery's point that bacterial flagella can perform their function with less than the 40 parts in its system that Behe claimed were essential to its functioning), Behe replies:
"some systems may have parts that are necessary for a function, plus other parts that, while useful, are not absolutely required. Although one can remove the radio from a car and the car will still work, one can't remove the battery or some other parts and have a working car."
(As Draper points out, Behe's analogy isn't quite apt, since a radio isn't a part of a car's primary function. However, Draper helps Behe out by replacing his example of a radio with that of a set of tires. Since tires aren't required for a car to drive, but do enhance its function, we have an apt illustration of Behe's point.)
Two initial remarks concerning Behe's reply to Ussery are in order. First, Behe's response tacitly concedes that Ussery is right, and thus that the bacterial flagellum fails to satisfy Behe's original definition of irreducible complexity (i.e., IC1). Second, and more to the main point in our discussion here, it tacitly replaces IC1 with a new definition of irreducible complexity -- call it 'IC2':
(IC2) A system S is irreducibly complex if and only if:
(i) S is composed of several interacting parts
(ii) S's parts are well-matched
(iii') A subset x of S's parts are such that removal of one or more of x's parts would cause S to cease functioning
The most important thing to notice about IC2 is that clause (iii) of IC1 has dropped out, and with it, its crucial implication that an irreducibly complex system requires all of its parts to function. In its place is a new clause -- clause (iii') -- which only entails the weaker claim that an irreducibly complex system requires a subset of its parts to function. Thus, unlike IC1, IC2 allows a system to count as irreducibly complex even if it has parts that aren't essential to its function.
Thus, with his revised account of irreducible complexity (IC2) in hand, we can put Behe's reply to Ussery as follows: granted, the point about the bacterial flagellum not being irreducibly complex, while strictly speaking correct, doesn't defeat the fundamental point that it contains a subset of parts, each of which must be present from the get-go for it to function at all. But systems like that -- systems that have at least a portion that is irreducibly complex -- can't evolve.
What to make of Behe's new definition of irreducible complexity? If you've been following the earlier posts, you might already see the problem with Behe's reply. For as we have seen in earlier installments, Behe allows that evolution can create simple irreducibly complex systems via indirect evolutionary pathways, and it that it can create reducibly complex systems via direct evolutionary pathways. But if so, then Behe has left open the very real possibility that his example systems have evolved via a two-staged combination of evolutionary pathways: an indirect pathway to create a simple yet irreducibly complex system in the first stage, and then a direct pathway to make that system very complex in the second stage. But such systems satisfy his revised account of irreducibly complex systems (i.e., IC2): systems containing both reducible complexity and an irreducibly complex (in the IC1 sense of 'irreducibly complex') core.
Now one might reply on behalf of Behe that although this sort of two-stage evolutionary process could produce irreducibly complex systems (in the IC2 sense) where the core set of interdependent parts is very simple, it can't account for Behe's example systems (e.g., the bacterial flagellum). For the core set of interdependent parts in those systems are very complex, and thus couldn't have evolved via indirect evolutionary pathways. But this reply won't work. For recall our discussion from the last installment. There, we saw Draper's point that Behe failed to show that his example systems are irreducibly very complex. For when Behe gets around to that task in Part II of his book, he only establishes examples of systems that are irreducibly complex and examples that are very complex. But showing those things is of course crucially different from showing what he needs to show here, viz, that at least some of his examples are irreducibly very complex.
But the problems with Behe's argument don't end here. For as Draper goes on to argue at the end of his article, Behe's arguments against simple direct and indirect evolutionary pathways to irreducibly very complex systems have very large holes in them. We'll wrap up our discussion of Draper's article by discussing these points in the next post or two.
Review of Timothy O'Connor's New Book, Theism and Ultimate Explanation
here (HT Prosblogion). It's a book-length defense of the cosmological argument from contingency. Timothy O'Connor is a first-rate philosopher, and a very clear writer, so you can bet the book is both an important contribution to the debate and a good read. He's primarily known for his work on the free will issue (he's one of the leading contemporary defenders of the libertarian position).
I should note that he's no fan of Plantinga's evolutionary argument against naturalism. In fact, he's published two excellent critiques of it here and here.
BTW: if you don't know already, Notre Dame Philosophical Reviews is an excellent source of philosophy book reviews. You can sign up at their site to have reviews of the latest books sent right to your email.
I should note that he's no fan of Plantinga's evolutionary argument against naturalism. In fact, he's published two excellent critiques of it here and here.
BTW: if you don't know already, Notre Dame Philosophical Reviews is an excellent source of philosophy book reviews. You can sign up at their site to have reviews of the latest books sent right to your email.
on vacation
Hi gang,
I'm currently on vacation at the beach, very much enjoying my family, friends, and self. I'll be back in about a week or so to finish the Draper article. In the meantime, be well!
Best,
EA
I'm currently on vacation at the beach, very much enjoying my family, friends, and self. I'll be back in about a week or so to finish the Draper article. In the meantime, be well!
Best,
EA
Notes on Draper's Article on Behe's Design Argument, Part 3: Are Behe's Examples irreducibly Complex?
We've been discussing Paul Draper's criticisms of Behe's design argument in Draper's 2002 article, "Irreducible Complexity and Darwinian Gradualism: A Reply to Michael J. Behe".[1] To briefly review, recall that the article focuses on stage one of Behe's two-stage design argument, which argues that certain biochemical structures cannot have arisen via Darwinian gradualistic processes. The argument of this stage crucially relies on his notion of irreducible complexity, where this is defined as a system "composed of several well-matched, interacting parts that contribute to the basic function, wherein removal of any of the parts causes the system to effectively cease functioning". [2] With this notion in hand, Behe argues that there are irreducibly very complex biochemical systems, and that these systems can't plausibly be explained in terms of gradualistic evolutionary processes. And the reason is that evolution can only create systems via direct and indirect evolutionary pathways. But evolution can create no irreducibly complex system via a direct evolutionary pathway. And while evolution can create simple irreducibly complex systems via indirect pathways, and reducibly complex systems via direct and indirect evolutionary pathways, the odds are overwhelmingly against creating irreducibly very complex systems via indirect pathways.
That's the argument laid out in Part I of Behe's book. In part II, Behe attempts to support the key premise that some biochemical systems are irreducibly (very) complex. Toward that end, he gives seven examples of such systems: (i) the bacterial flagellum, (ii) the cilium, (iii) the vertebrate blood-clotting system, (iv) certain cellular transport systems, and three subsystems of our immune system: (v) the clonal selection system (vi) the antibody-diversity system, and (vii) the complement system. Given this, and given his argument, there are at least three ways to criticize his argument directly:
(1) Undercut or rebut the claim that his example systems are irreducibly complex (or at least irreducibly very complex)
(2) Undercut or rebut the claim that irreducibly complex systems can't be created via indirect evolutionary pathways
(3) Undercut or rebut the claim that irreducibly complex systems can't be created via direct evolutionary pathways
Draper argues that Behe's argument falls prey to all three types of criticism. In this installment, I'll cover most of his discussion of type-(1) criticisms.
First, Draper points to the work of others to offer rebutting defeaters for a number of Behe's candidates of irreducibly complex systems. So, for example, consider Behe's cilium example. Behe argues that cillia require eleven microtubules to function: two central microtubules surrounded by nine encasing microtubules. But Draper refers to Ken Miller's point that some organisms have cilia with three microtubules and no inner microtubules. Therefore, since cilia don't require all eleven parts to function, Behe's cillium example fails to satisfy his own account of irreducible complexity. A similar problem plagues Behe's flagellum example. Behe asserts that the bacterial flagellum requires at least 40 parts to function. But Draper refers to biochemist David W. Ussery's point that some forms of bacteria have flagella that only require 33 parts to function. But if so, then since the bacterial flagellum doesn't require all 40 parts to perform its function, then by Behe's definition, it isn't irreducibly complex. Draper points out that the same criticism applies to Behe's immune system and cellular transport examples.
Second, Draper points out that Behe fails to show that his own example systems are irreducibly complex. On p. 42 of Darwin's Black Box, Behe states his two-step method of testing and demonstrating whether a system is irreducibly complex:
Step 1: Find the system's function, and identify all the components that contribute to that function.
Step 2: Determine whether all of the system's components are required for it to perform the function.
But when it comes time to argue that his example systems are irreducibly complex (in Part II of the book), he fails to follow (at least) Step 2 for any of his example systems. Instead, he typically picks a proper subset of a system's total components, and argues that the system can't function without them. So, for example, in his discussion of the cilium on p. 73, he says that it has "dozens or even hundreds" of parts involved in its function. However, instead of explaining how each of these parts is necessary for the function of the system, he picks four of them, discusses their essentiality for performing the paddling function, and then fleetingly asserts that probably many other of its parts are essential as well [3]. As mentioned above, and as Draper points out, Behe continues to ignore Step 2 in his presentations of the remaining five example systems as well. The result is that a crucial premise in the main argument of Behe's book -- that there are irreducibly very complex biochemical systems -- is left unargued for.
Draper nicely sums up the problems with Behe's claim that some biochemical structures are irreducibly (very) complex: "The bottom line is that Behe doesn't deliver in the second part of his book what he promised in the first part...The systems upon which he bases his case contain parts that contribute to the system's function, yet either are not essential for that function or at least have not been shown by Behe to be so."[4]
As Draper points out, however, Behe has come up with a reply to this criticism. We'll look at it in the next installment.
----------------------------------------------------------------
Notes
[1]Faith and Philosophy 19:1, pp. 3-21.
[2] Behe, Michael J. Darwin's Black Box: The Biochemical Challenge to Evolution (New York: The Free Press, 1996), p. 39.
[3] p. 73
[4] Draper, ibid, p. 10.
That's the argument laid out in Part I of Behe's book. In part II, Behe attempts to support the key premise that some biochemical systems are irreducibly (very) complex. Toward that end, he gives seven examples of such systems: (i) the bacterial flagellum, (ii) the cilium, (iii) the vertebrate blood-clotting system, (iv) certain cellular transport systems, and three subsystems of our immune system: (v) the clonal selection system (vi) the antibody-diversity system, and (vii) the complement system. Given this, and given his argument, there are at least three ways to criticize his argument directly:
(1) Undercut or rebut the claim that his example systems are irreducibly complex (or at least irreducibly very complex)
(2) Undercut or rebut the claim that irreducibly complex systems can't be created via indirect evolutionary pathways
(3) Undercut or rebut the claim that irreducibly complex systems can't be created via direct evolutionary pathways
Draper argues that Behe's argument falls prey to all three types of criticism. In this installment, I'll cover most of his discussion of type-(1) criticisms.
First, Draper points to the work of others to offer rebutting defeaters for a number of Behe's candidates of irreducibly complex systems. So, for example, consider Behe's cilium example. Behe argues that cillia require eleven microtubules to function: two central microtubules surrounded by nine encasing microtubules. But Draper refers to Ken Miller's point that some organisms have cilia with three microtubules and no inner microtubules. Therefore, since cilia don't require all eleven parts to function, Behe's cillium example fails to satisfy his own account of irreducible complexity. A similar problem plagues Behe's flagellum example. Behe asserts that the bacterial flagellum requires at least 40 parts to function. But Draper refers to biochemist David W. Ussery's point that some forms of bacteria have flagella that only require 33 parts to function. But if so, then since the bacterial flagellum doesn't require all 40 parts to perform its function, then by Behe's definition, it isn't irreducibly complex. Draper points out that the same criticism applies to Behe's immune system and cellular transport examples.
Second, Draper points out that Behe fails to show that his own example systems are irreducibly complex. On p. 42 of Darwin's Black Box, Behe states his two-step method of testing and demonstrating whether a system is irreducibly complex:
Step 1: Find the system's function, and identify all the components that contribute to that function.
Step 2: Determine whether all of the system's components are required for it to perform the function.
But when it comes time to argue that his example systems are irreducibly complex (in Part II of the book), he fails to follow (at least) Step 2 for any of his example systems. Instead, he typically picks a proper subset of a system's total components, and argues that the system can't function without them. So, for example, in his discussion of the cilium on p. 73, he says that it has "dozens or even hundreds" of parts involved in its function. However, instead of explaining how each of these parts is necessary for the function of the system, he picks four of them, discusses their essentiality for performing the paddling function, and then fleetingly asserts that probably many other of its parts are essential as well [3]. As mentioned above, and as Draper points out, Behe continues to ignore Step 2 in his presentations of the remaining five example systems as well. The result is that a crucial premise in the main argument of Behe's book -- that there are irreducibly very complex biochemical systems -- is left unargued for.
Draper nicely sums up the problems with Behe's claim that some biochemical structures are irreducibly (very) complex: "The bottom line is that Behe doesn't deliver in the second part of his book what he promised in the first part...The systems upon which he bases his case contain parts that contribute to the system's function, yet either are not essential for that function or at least have not been shown by Behe to be so."[4]
As Draper points out, however, Behe has come up with a reply to this criticism. We'll look at it in the next installment.
----------------------------------------------------------------
Notes
[1]Faith and Philosophy 19:1, pp. 3-21.
[2] Behe, Michael J. Darwin's Black Box: The Biochemical Challenge to Evolution (New York: The Free Press, 1996), p. 39.
[3] p. 73
[4] Draper, ibid, p. 10.
Notes on Draper's Article on Behe's Design Argument, Part 2: Three Bad Criticisms
Here is the second installment of notes on Paul Draper's important article critiquing Behe's design argument, "Irreducible Complexity and Darwinian Gradualism: A Reply to Michael J. Behe", Faith and Philosophy 19:1 (2002), pp. 3-21
Draper points out that three common criticisms of Behe's irreducible complexity argument miss the mark.
I. Bad Objection #1: Other Biochemical Systems are Reducibly Complex and Evolvable
First, some have argued that lots of biochemical systems exhibit redundancy, which shows that such systems are not irreducibly complex. But Draper points out that this doesn't refute Behe's argument. For recall that Behe isn't committed to the claim that all biochemical systems are irreducibly complex, but rather the weaker claim that at least some are, and that some of these (viz., those that are very complex) could not have evolved through gradualistic evolutionary processes. Behe isn't your standard creationist: he thinks the evidence for the key evolutionary theses of common ancestry and descent with modification are persuasive. He also thinks that gradualistic evolutionary mechanisms can account for many biochemical structures as well -- viz., those that are reducibly complex. But the authors in question don't address the particular examples of biochemical systems that Behe argues are irreducibly very complex (e.g., the bacterial flagellum).
II. Bad Objection #2: Very Simple Irreducibly Complex Systems are Evolvable
Second, a number of people -- most prominently, cell biologist and devout Catholic Kenneth Miller -- have argued that certain structures are irreducibly complex, and yet have clearly evolved gradually. So, for example, MIller points out that the three-boned structure within the inner mammalian ear is irreducibly complex, and yet we have excellent evidence that it evolved via an indirect evolutionary pathway from parts of the jaws of reptilian evolutionary predecessors. But this doesn't refute Behe's argument, either. For recall that Behe argues that while no irreducibly complex system can evolve via a direct evolutionary pathway, he grants that a relatively simple irreducibly complex structure can evolve via an indirect evolutionary pathway: "Even if a system is irreducibly complex (and thus cannot have been produced directly), however, one can not definitively rule out the possibility of an indirect, circuitous route. As the complexity of an interacting system increases, though, the likelihood of such an indirect route drops precipitously." Behe, Darwin's Black Box, P. 40.
In short, the first two popular criticisms of Behe's argument miss the mark. For these are based on examples of reducibly complex systems and simple irreducibly complex systems that have arisen via gradualistic evolutionary pathways. But to touch Behe's argument, one needs an example of an irreducibly very complex system that has arisen via a gradualistic evolutionary pathway.
III. Bad Objection #3: It's Just Paley's Bad Analogical Design Argument in New Packaging
Finally, a number of people have claimed that Behe's argument is just a re-statement of Paley's design argument, and since Paley's version falls prey to Hume's and Darwin's criticisms, so does Behe's. But Draper argues that while Behe has contributed to this perception (he explicitly identifies his argument with Paley's), it is nonetheless a misleading and uncharitable criticism. This is because most people think of Paley's argument as the one Hume attacked, viz., an argument from analogy, and having the following form:
1. Human artifacts are intelligently designed.
2. The universe, or some of its parts, resemble human artifacts.
-----------------------------------
3. Therefore, the universe, or some of its parts, were (probably) intelligently designed.
But as Elliot Sober has argued[1], while Paley talked about an analogy between watches and organisms, his actual argument wasn't itself an argument from analogy. Rather, it was an abductive argument to the best available explanation:
1. Some natural systems (e.g., the human eye) are mechanically ordered (i.e., they exhibit the same sort of order as watches and other machines produced by human beings).
2. Intelligent design is a very good explanation of mechanical order.
3. No other explanation (or no equally good explanation) of mechanical order is available.
4. Every instance of mechanical order has an explanation.
-------------
5. So, some natural systems were (probably) intelligently designed.
But if so, then at least three things can be said on behalf of Behe in response to the third criticism. First, while the critics may be right that Hume refuted the analogical version of the design argument, they're wrong to think that Hume refuted Paley's design argument. For his is the abductive version, and Hume's criticisms don't refute it. And if Behe is defending Paley's abductive argument, it follows that it's not enough to point to Hume to answer Behe's argument.
Second, Behe has made a genuine contribution to improving Paley's argument by articulating an account of mechanical order mentioned in the premises, viz., his notion of irreducible complexity.
The previous point brings us to the third. For while many would argue that Darwin refuted Paley's abductive argument (even if Hume did not), Behe has strengthened Paley's argument in a way that requires more of a response than just pointing to Darwin. For Darwin and subsequent scientists have only shown how biological systems larger than biochemical structures can evolve gradually. But that's consistent with the claim that the smaller, biochemical structures cannot evolve gradually. And as we saw in a previous post, Behe has argued just this: certain biochemical structures (e.g., the bacterial flagellum) are irreducibly very complex, and thus couldn't have arisen via direct or indirect evolutionary pathways. Therefore, we have another reason for thinking that Behe's argument can't be dismissed by just pointing to earlier critiques of the design argument.
We've just seen three common criticisms of Behe's argument that don't seem to work. In the remaining posts in this series, we'll take a look at three criticisms that seem telling.
----------------------------------------------------------------
Notes
[1] Philosophy of Biology (Boulder, CO: Westview Press, 1993), pp. 34-35. Draper's reference, "Irreducible Complexity and Darwinian Gradualism", p. 7.
Draper points out that three common criticisms of Behe's irreducible complexity argument miss the mark.
I. Bad Objection #1: Other Biochemical Systems are Reducibly Complex and Evolvable
First, some have argued that lots of biochemical systems exhibit redundancy, which shows that such systems are not irreducibly complex. But Draper points out that this doesn't refute Behe's argument. For recall that Behe isn't committed to the claim that all biochemical systems are irreducibly complex, but rather the weaker claim that at least some are, and that some of these (viz., those that are very complex) could not have evolved through gradualistic evolutionary processes. Behe isn't your standard creationist: he thinks the evidence for the key evolutionary theses of common ancestry and descent with modification are persuasive. He also thinks that gradualistic evolutionary mechanisms can account for many biochemical structures as well -- viz., those that are reducibly complex. But the authors in question don't address the particular examples of biochemical systems that Behe argues are irreducibly very complex (e.g., the bacterial flagellum).
II. Bad Objection #2: Very Simple Irreducibly Complex Systems are Evolvable
Second, a number of people -- most prominently, cell biologist and devout Catholic Kenneth Miller -- have argued that certain structures are irreducibly complex, and yet have clearly evolved gradually. So, for example, MIller points out that the three-boned structure within the inner mammalian ear is irreducibly complex, and yet we have excellent evidence that it evolved via an indirect evolutionary pathway from parts of the jaws of reptilian evolutionary predecessors. But this doesn't refute Behe's argument, either. For recall that Behe argues that while no irreducibly complex system can evolve via a direct evolutionary pathway, he grants that a relatively simple irreducibly complex structure can evolve via an indirect evolutionary pathway: "Even if a system is irreducibly complex (and thus cannot have been produced directly), however, one can not definitively rule out the possibility of an indirect, circuitous route. As the complexity of an interacting system increases, though, the likelihood of such an indirect route drops precipitously." Behe, Darwin's Black Box, P. 40.
In short, the first two popular criticisms of Behe's argument miss the mark. For these are based on examples of reducibly complex systems and simple irreducibly complex systems that have arisen via gradualistic evolutionary pathways. But to touch Behe's argument, one needs an example of an irreducibly very complex system that has arisen via a gradualistic evolutionary pathway.
III. Bad Objection #3: It's Just Paley's Bad Analogical Design Argument in New Packaging
Finally, a number of people have claimed that Behe's argument is just a re-statement of Paley's design argument, and since Paley's version falls prey to Hume's and Darwin's criticisms, so does Behe's. But Draper argues that while Behe has contributed to this perception (he explicitly identifies his argument with Paley's), it is nonetheless a misleading and uncharitable criticism. This is because most people think of Paley's argument as the one Hume attacked, viz., an argument from analogy, and having the following form:
1. Human artifacts are intelligently designed.
2. The universe, or some of its parts, resemble human artifacts.
-----------------------------------
3. Therefore, the universe, or some of its parts, were (probably) intelligently designed.
But as Elliot Sober has argued[1], while Paley talked about an analogy between watches and organisms, his actual argument wasn't itself an argument from analogy. Rather, it was an abductive argument to the best available explanation:
1. Some natural systems (e.g., the human eye) are mechanically ordered (i.e., they exhibit the same sort of order as watches and other machines produced by human beings).
2. Intelligent design is a very good explanation of mechanical order.
3. No other explanation (or no equally good explanation) of mechanical order is available.
4. Every instance of mechanical order has an explanation.
-------------
5. So, some natural systems were (probably) intelligently designed.
But if so, then at least three things can be said on behalf of Behe in response to the third criticism. First, while the critics may be right that Hume refuted the analogical version of the design argument, they're wrong to think that Hume refuted Paley's design argument. For his is the abductive version, and Hume's criticisms don't refute it. And if Behe is defending Paley's abductive argument, it follows that it's not enough to point to Hume to answer Behe's argument.
Second, Behe has made a genuine contribution to improving Paley's argument by articulating an account of mechanical order mentioned in the premises, viz., his notion of irreducible complexity.
The previous point brings us to the third. For while many would argue that Darwin refuted Paley's abductive argument (even if Hume did not), Behe has strengthened Paley's argument in a way that requires more of a response than just pointing to Darwin. For Darwin and subsequent scientists have only shown how biological systems larger than biochemical structures can evolve gradually. But that's consistent with the claim that the smaller, biochemical structures cannot evolve gradually. And as we saw in a previous post, Behe has argued just this: certain biochemical structures (e.g., the bacterial flagellum) are irreducibly very complex, and thus couldn't have arisen via direct or indirect evolutionary pathways. Therefore, we have another reason for thinking that Behe's argument can't be dismissed by just pointing to earlier critiques of the design argument.
We've just seen three common criticisms of Behe's argument that don't seem to work. In the remaining posts in this series, we'll take a look at three criticisms that seem telling.
----------------------------------------------------------------
Notes
[1] Philosophy of Biology (Boulder, CO: Westview Press, 1993), pp. 34-35. Draper's reference, "Irreducible Complexity and Darwinian Gradualism", p. 7.
Interesting Discussion of Plantinga's Evolutionary Argument Against Naturalism (EAAN)
at Prosblogion, here. See Michael Almeida's dilemma against EAAN in the comments thread, and the subsequent discussion.
Notes on Draper's Article on Behe's Design Argument, Part 1: The Argument Stated and Explained
For the next several posts, I'll be writing on Paul Draper's article, "Irreducible Complexity and Darwinian Gradualism: A Reply to Michael J. Behe", Faith and Philosophy 19:1 (2002), pp. 3-21. Here's the first installment.
I. General
Michael Behe is a biochemist at Lehigh University. He uses his knowledge of biochemistry for the basis of the first stage of his two-stage design argument. In the first stage, he argues that certain biochemical structures (e.g., the bacterial flagellum and the blood-clotting cascade) could not have arisen through the gradualistic processes of evolution. In the second stage, he argues that if such structures could not have arisen in stepwise Darwinian fashion, then it's very probable that they were produced by one or more intelligent designers. Draper's article focuses on the first stage of Behe's argument.
II. Irreducible Complexity
The central notion of Behe's argument is what he calls 'irreducible complexity'. Behe defines an irreducibly complex system as one "composed of several well-matched, interacting parts that contribute to the basic function, wherein removal of any of the parts causes the system to effectively cease functioning" [1]. He uses a mousetrap to illustrate the notion of an irreducibly complex system. A standard mousetrap has five parts: a hammer, a spring, a holding bar, a catch, and a base. The mousetrap is composed of several well-matched, interacting parts that contribute to the basic function. Furthermore, it appears that the mousetrap would effectively cease functioning (i.e., it would lose it's ability to catch mice) with the removal of any of the five parts listed above: it needs the hammer to clamp down on the mouse; it needs the spring and holding bar to arm the hammer; it needs the catch to detect the mouse; and it needs the base to secure the other parts. Therefore, the mousetrap appears to be a helpful illustration of the notion of an irreducibly complex system. As we will see, Behe argues that certain biochemical structures are irreducibly complex, and that such structures pose a serious challenge to evolution.
III. Evolutionary Pathways
Before we state Behe's argument against Darwinian gradualism, we need to briefly discuss what are ostensibly the only two sorts of evolutionary pathways for creating biological systems: direct and indirect. A gradualistic evolutionary pathway leading to a function F of a biological system is direct if it produces F by continuously improving it without changing F itself, and without changing the system's mechanism. And a gradualistic evolutionary pathway leading to F is indirect if it does so by changing the system's function or mechanism .[2]
IV. Behe's Argument
With the notions of direct evolutionary pathways, indirect evolutionary pathways, and irreducible complexity before us, we can now state Behe's argument against Darwinian gradualism: There are irreducibly complex biochemical systems (e.g., the bacterial flagellum and the blood-clotting cascade). Now if Darwinian gradualism is true, then each such system is created via either a direct or an indirect evolutionary pathway. But no irreducibly complex biochemical system can be created via a direct evolutionary pathway, for any precursor to an irreducibly complex system is by definition non-functional.[3] And while it's possible in principle to create an irreducibly complex biochemical system via an indirect pathway, the probability of this happening is too low to be plausible for systems that are very complex (and there are such systems).[4] Therefore, it's very probable that Darwinian gradualism is false.[5]
V. Key Aspects of Behe's Argument, and an Important Implication
As Draper points out, Behe's argument against direct evolutionary pathways to irreducibly complex biochemical systems differs from his argument against indirect pathways: direct pathways are ruled out by the irreducibility of the complexity with respect to function, and indirect pathways are ruled out by the complexity of such systems. Direct pathways to all irreducibly complex systems are therefore ruled out as logically impossible, while indirect pathways to irreducibly very complex systems are ruled out as too improbable to be a plausible explanation. Note (as Draper does in his article) that Behe's argument leaves open the possibility of relatively simple irreducibly complex systems (say, systems with two or three parts) being produced gradually via indirect evolutionary pathways. This will be important to keep in mind for later posts.
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Notes
[1] Behe, Michael J. Darwin's Black Box: The Biochemical Challenge to Evolution (New York: The Free Press, 1996), p. 39.
[2] Draper, Paul. "Irreducible Complexity and Darwinian Gradualism: A Reply to Michael J. Behe", Faith and Philosophy 19:1 (2002), p. 5
[3] Irreducibly complex systems "cannot be produced directly, because any precursor to an irreducibly complex system that is missing even a single part is by definition nonfunctional." Darwin's Black Box, P. 39. The quote appears in Draper, ibid.
[4] "Even if a system is irreducibly complex (and thus cannot have been produced directly), however, one can not definitively rule out the possibility of an indirect, circuitous route. As the complexity of an interacting system increases, though, the likelihood of such an indirect route drops precipitously." Behe, Darwin's Black Box, P. 40.
[5] This summary is closely based on Draper's. See ibid, p. 5.
I. General
Michael Behe is a biochemist at Lehigh University. He uses his knowledge of biochemistry for the basis of the first stage of his two-stage design argument. In the first stage, he argues that certain biochemical structures (e.g., the bacterial flagellum and the blood-clotting cascade) could not have arisen through the gradualistic processes of evolution. In the second stage, he argues that if such structures could not have arisen in stepwise Darwinian fashion, then it's very probable that they were produced by one or more intelligent designers. Draper's article focuses on the first stage of Behe's argument.
II. Irreducible Complexity
The central notion of Behe's argument is what he calls 'irreducible complexity'. Behe defines an irreducibly complex system as one "composed of several well-matched, interacting parts that contribute to the basic function, wherein removal of any of the parts causes the system to effectively cease functioning" [1]. He uses a mousetrap to illustrate the notion of an irreducibly complex system. A standard mousetrap has five parts: a hammer, a spring, a holding bar, a catch, and a base. The mousetrap is composed of several well-matched, interacting parts that contribute to the basic function. Furthermore, it appears that the mousetrap would effectively cease functioning (i.e., it would lose it's ability to catch mice) with the removal of any of the five parts listed above: it needs the hammer to clamp down on the mouse; it needs the spring and holding bar to arm the hammer; it needs the catch to detect the mouse; and it needs the base to secure the other parts. Therefore, the mousetrap appears to be a helpful illustration of the notion of an irreducibly complex system. As we will see, Behe argues that certain biochemical structures are irreducibly complex, and that such structures pose a serious challenge to evolution.
III. Evolutionary Pathways
Before we state Behe's argument against Darwinian gradualism, we need to briefly discuss what are ostensibly the only two sorts of evolutionary pathways for creating biological systems: direct and indirect. A gradualistic evolutionary pathway leading to a function F of a biological system is direct if it produces F by continuously improving it without changing F itself, and without changing the system's mechanism. And a gradualistic evolutionary pathway leading to F is indirect if it does so by changing the system's function or mechanism .[2]
IV. Behe's Argument
With the notions of direct evolutionary pathways, indirect evolutionary pathways, and irreducible complexity before us, we can now state Behe's argument against Darwinian gradualism: There are irreducibly complex biochemical systems (e.g., the bacterial flagellum and the blood-clotting cascade). Now if Darwinian gradualism is true, then each such system is created via either a direct or an indirect evolutionary pathway. But no irreducibly complex biochemical system can be created via a direct evolutionary pathway, for any precursor to an irreducibly complex system is by definition non-functional.[3] And while it's possible in principle to create an irreducibly complex biochemical system via an indirect pathway, the probability of this happening is too low to be plausible for systems that are very complex (and there are such systems).[4] Therefore, it's very probable that Darwinian gradualism is false.[5]
V. Key Aspects of Behe's Argument, and an Important Implication
As Draper points out, Behe's argument against direct evolutionary pathways to irreducibly complex biochemical systems differs from his argument against indirect pathways: direct pathways are ruled out by the irreducibility of the complexity with respect to function, and indirect pathways are ruled out by the complexity of such systems. Direct pathways to all irreducibly complex systems are therefore ruled out as logically impossible, while indirect pathways to irreducibly very complex systems are ruled out as too improbable to be a plausible explanation. Note (as Draper does in his article) that Behe's argument leaves open the possibility of relatively simple irreducibly complex systems (say, systems with two or three parts) being produced gradually via indirect evolutionary pathways. This will be important to keep in mind for later posts.
-------------------------------------------
Notes
[1] Behe, Michael J. Darwin's Black Box: The Biochemical Challenge to Evolution (New York: The Free Press, 1996), p. 39.
[2] Draper, Paul. "Irreducible Complexity and Darwinian Gradualism: A Reply to Michael J. Behe", Faith and Philosophy 19:1 (2002), p. 5
[3] Irreducibly complex systems "cannot be produced directly, because any precursor to an irreducibly complex system that is missing even a single part is by definition nonfunctional." Darwin's Black Box, P. 39. The quote appears in Draper, ibid.
[4] "Even if a system is irreducibly complex (and thus cannot have been produced directly), however, one can not definitively rule out the possibility of an indirect, circuitous route. As the complexity of an interacting system increases, though, the likelihood of such an indirect route drops precipitously." Behe, Darwin's Black Box, P. 40.
[5] This summary is closely based on Draper's. See ibid, p. 5.
The Single Best Article on Behe's Design Argument From Irreducible Complexity
...is Paul Draper's "Irreducible Complexity and Darwinian Gradualism: A Reply to Michael J. Behe". Faith and Philosophy 19:1 (2002), pp. 3-21.
Draper is my favorite philosopher of religion. If you haven't read his stuff, I encourage you to do so!
Btw: he's the current editor of Philo, which is the non-theistic counterpart of the premier philosophy of religion journal, Faith and Philosophy (although some say Philosophia Christi may overtake it)
Draper is my favorite philosopher of religion. If you haven't read his stuff, I encourage you to do so!
Btw: he's the current editor of Philo, which is the non-theistic counterpart of the premier philosophy of religion journal, Faith and Philosophy (although some say Philosophia Christi may overtake it)
Post Index: Argument from Contingency
1. Explaining and Defending the Argument
1.1 The argument stated and explained
1.2 Outline of Rowe's chapter on the argument in his Philosophy of Religion: part I, part II
1.3 Defending the argument against common criticisms
2. Criticisms of the Argument
2.1 Summary of some more serious criticisms of the argument
2.2 Mackie's criticisms of the argument
2.3 Peter van Inwagen's criticisms of the argument
2.4 Summary of my own worry for the argument
1.1 The argument stated and explained
1.2 Outline of Rowe's chapter on the argument in his Philosophy of Religion: part I, part II
1.3 Defending the argument against common criticisms
2. Criticisms of the Argument
2.1 Summary of some more serious criticisms of the argument
2.2 Mackie's criticisms of the argument
2.3 Peter van Inwagen's criticisms of the argument
2.4 Summary of my own worry for the argument
Outline of Rowe's Chapter on the Argument from Contingency in His Philosophy of Religion, Part II
Notes on Rowe on the Cosmological Argument, Part Two: Four Criticisms of the Argument
0. Review
0.1 Dependent beings: a being whose existence is accounted for by the causal activity of other beings
0.2 Self-existent beings: beings whose existence is self-explanatory, or accounted for by their own inner nature
0.3 The Principle of Sufficient Reason (PSR): There must be an explanation for (a) the existence of every object, and (b) of every positive fact whatsoever, either in terms of something else or in terms of its own inner nature.
0.4 The basic argument:
1. Either everything is a dependent being, or there is a self-existent being.
2. Not everything is a dependent being.
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3. Therefore, there is a self-existent being.
1. First Criticism: Dependence and the fallacy of composition
1.1 The argument fallaciously assumes that because each member of the collection of beings within the universe is dependent, that therefore the whole collection of such beings is itself dependent. But this doesn’t follow.
1.2 Reply: It would be fallacious to assume this, but the defender of the cosmological argument need not assume it for the argument to work. Rather, since the existence of the collection of dependent beings is a positive fact, then it follows from PSR(b) that there must be a sufficient reason for why the collection exists.
2. Second Criticism: Causation and the fallacy of composition
2.1 The argument fallaciously assumes that because each member of the collection of dependent beings has a cause, that therefore the whole collection of dependent beings has a cause. But this doesn’t follow.
2.2 Reply: It would be fallacious to assume this, but the defender of the cosmological argument need not assume it for the argument to work. Rather, since the existence of the collection of dependent beings is a positive fact, then it follows from PSR(b) that there must be a sufficient reason for why the collection exists.
3. Third Criticism: Nothing’s left to explain
3.1 The defender of the cosmological argument fails to see that once the existence of each member of the collection of dependent beings is explained, the existence of the whole collection is thereby explained.
3.2 Reply: This isn’t necessarily true
4. Fourth Criticism: What’s wrong with brute facts?
4.1 The argument assumes that it’s impossible for there to be brute facts – facts involving contingent beings or events that have no further explanation.
4.2 But what’s wrong with this, exactly? It turns out that it all turns on whether you accept PSR.
4.3 Thus, to see if this criticism of the cosmological argument is any good, we must first see what reason there is to accept PSR. Let’s do so now.
5. Two arguments for PSR
5.1 It’s self-evident
5.1.1 Self-evident propositions are those that, once you understand what they mean, you automatically see that they’re necessarily true. Here are some examples: all triangles have three sides; all red things are colored things; nothing could be red all over and green all over at the same time.
5.1.2 The defender of the cosmological argument claims that the same is true of PSR: once you understand it, you automatically see that it’s necessarily true.
5.1.3 The problem: lots of people who have thought about it for a long time – and thus, presumably, understand what it means – nevertheless fail to see that it’s necessarily true. If so, then this seems to be evidence that it’s not self-evident.
5.2 It’s not known to be true, but it’s a presupposition of reason:
5.2.1 it’s a basic assumption that all people make – or perhaps must make – in order to be rational.
5.2.2 Compare: believing that there are material objects; believing that the there is a past (as opposed to our being created 10 minutes ago, with our minds implanted with false memories, etc.)
5.2.3 Similarly, belief in PSR is a basic assumption like these that all rational people do – and perhaps must – accept in order to be rational.
5.2.4 Some problems:
5.4.1 from the fact that we must presuppose PSR in order to be rational, it doesn’t follow that it’s true.
5.4.2 granted, if PSR really is a presupposition of reason, we should accept it in order to be rationally consistent. But unfortunately, it’s not clear that it is a presupposition of reason.
0. Review
0.1 Dependent beings: a being whose existence is accounted for by the causal activity of other beings
0.2 Self-existent beings: beings whose existence is self-explanatory, or accounted for by their own inner nature
0.3 The Principle of Sufficient Reason (PSR): There must be an explanation for (a) the existence of every object, and (b) of every positive fact whatsoever, either in terms of something else or in terms of its own inner nature.
0.4 The basic argument:
1. Either everything is a dependent being, or there is a self-existent being.
2. Not everything is a dependent being.
----------------------------------------------------------------------------------
3. Therefore, there is a self-existent being.
1. First Criticism: Dependence and the fallacy of composition
1.1 The argument fallaciously assumes that because each member of the collection of beings within the universe is dependent, that therefore the whole collection of such beings is itself dependent. But this doesn’t follow.
1.2 Reply: It would be fallacious to assume this, but the defender of the cosmological argument need not assume it for the argument to work. Rather, since the existence of the collection of dependent beings is a positive fact, then it follows from PSR(b) that there must be a sufficient reason for why the collection exists.
2. Second Criticism: Causation and the fallacy of composition
2.1 The argument fallaciously assumes that because each member of the collection of dependent beings has a cause, that therefore the whole collection of dependent beings has a cause. But this doesn’t follow.
2.2 Reply: It would be fallacious to assume this, but the defender of the cosmological argument need not assume it for the argument to work. Rather, since the existence of the collection of dependent beings is a positive fact, then it follows from PSR(b) that there must be a sufficient reason for why the collection exists.
3. Third Criticism: Nothing’s left to explain
3.1 The defender of the cosmological argument fails to see that once the existence of each member of the collection of dependent beings is explained, the existence of the whole collection is thereby explained.
3.2 Reply: This isn’t necessarily true
4. Fourth Criticism: What’s wrong with brute facts?
4.1 The argument assumes that it’s impossible for there to be brute facts – facts involving contingent beings or events that have no further explanation.
4.2 But what’s wrong with this, exactly? It turns out that it all turns on whether you accept PSR.
4.3 Thus, to see if this criticism of the cosmological argument is any good, we must first see what reason there is to accept PSR. Let’s do so now.
5. Two arguments for PSR
5.1 It’s self-evident
5.1.1 Self-evident propositions are those that, once you understand what they mean, you automatically see that they’re necessarily true. Here are some examples: all triangles have three sides; all red things are colored things; nothing could be red all over and green all over at the same time.
5.1.2 The defender of the cosmological argument claims that the same is true of PSR: once you understand it, you automatically see that it’s necessarily true.
5.1.3 The problem: lots of people who have thought about it for a long time – and thus, presumably, understand what it means – nevertheless fail to see that it’s necessarily true. If so, then this seems to be evidence that it’s not self-evident.
5.2 It’s not known to be true, but it’s a presupposition of reason:
5.2.1 it’s a basic assumption that all people make – or perhaps must make – in order to be rational.
5.2.2 Compare: believing that there are material objects; believing that the there is a past (as opposed to our being created 10 minutes ago, with our minds implanted with false memories, etc.)
5.2.3 Similarly, belief in PSR is a basic assumption like these that all rational people do – and perhaps must – accept in order to be rational.
5.2.4 Some problems:
5.4.1 from the fact that we must presuppose PSR in order to be rational, it doesn’t follow that it’s true.
5.4.2 granted, if PSR really is a presupposition of reason, we should accept it in order to be rationally consistent. But unfortunately, it’s not clear that it is a presupposition of reason.
Outline of Rowe's Chapter on the Argument from Contingency in His Philosophy of Religion, Part I
Notes on Rowe on the Cosmological Argument, Part One
1. Setup: Terminology
1.1 Dependent beings: a being whose existence is accounted for by the causal activity of other beings
1.2 Self-existent beings: beings whose existence is self-explanatory, or accounted for by their own inner nature
1.3 The Principle of Sufficient Reason (PSR): There must be an explanation for (a) the existence of every being, and (b) of every positive fact whatsoever, either in terms of something else or in terms of its own inner nature.
2. The Argument:
2.1 (1) Either everything is a dependent being, or there is a self-existent being.
2.1 (2) Not everything is a dependent being.
2.3 (3) Therefore, there is a self-existent being.
2.4 The argument is valid, since it has the valid argument form of Disjunctive Syllogism ((1) P or Q, (2) Not-P; therefore, (3) Q)
2.5 So, if the premises are both true, the conclusion follows of necessity.
2.6 So what is the evidence for the premises?
3. The Case for Premise 1: There can be no being that has no explanation at all (i.e., no explanation in terms of other beings, and no explanation in terms of its own nature)
3.1. Premise 1 states that either all beings are dependent, or there is at least one self-existent being.
3.2 But at first glance, at least, this seems false. For notice that there seem to be at least three types of beings that there could be
3.2.1 beings explained by one or more other beings
3.2.2 beings explained by nothing
3.2.3 beings explained by their own nature – self-explanatory beings
3.3 But the argument we’re discussing assumes that the second type of being is impossible
3.4 Why think that? If it’s wrong about that, then the argument doesn’t work
3.5 Answer: it assumes PSR
3.5.1 If the second type of being could exist, then it would have no explanation whatsoever for why it exists – it just does, and that’s all there is to say about it
3.5.2 But PSR says that everything has an explanation for why it exists, either in terms of something else or in terms of its own inner nature.
3.5.3 Thus, if PSR is true, then there can be no such beings.
3.6 Thus, PSR, if true, rules out this second type of being, and in this way, PSR supports premise (1).
4. The Case for Premise 2: Dependent beings can’t be accounted for in terms of just other dependent beings, no matter how many
4.1 The reason is not because every series of dependent beings must have a temporal "first" being to cause the others.
4.1.1 There are other versions of the cosmological argument that reason in that way.
4.1.2 But this version of the argument allows that a beginningless series of dependent beings is possible in principle
4.2 The real reason:
4.2.1 It's because, even if the series of dependent beings goes back forever, the existence of the series of dependent beings would itself be just another dependent being.
4.2.2 But if so, then by PSR(a), it too would need an explanation or sufficient reason for why it exists, and PSR says it must have one before we can legitimately stop our quest of explanations.
4.2.3 But even if the series of dependent beings isn't itself a being, the existence of the series of dependent beings is a positive fact or state of affairs.
4.2.4 But if so, then by PSR(b), it, too, would need an explanation for why it obtains.
4.2.5 Another way to think of it: even if there is an infinite series of dependent beings that goes back through eternity, we would still need an explanation for why there have always been dependent beings (as opposed to there being nothing).
4.2.6 Thus, no matter which way you slice it, dependent beings are inherently incapable of accounting for their own existence.
5. Conclusion:
5.1 The cosmological argument from contingency is logically valid; so if the premises are true, the conclusion follows of logical necessity.
5.2 Furthermore, there is a good prima facie case for the premises, as we've just seen
5.2.1 Premise 1 is supported by PSR, which rules out the existence of brute facts, i.e., beings that have no explanation for why they exist.
5.2.2 Premise 2 is supported by the apparent fact that dependent beings are inherently incapable of accounting for/explaining themselves.
5.3 If all these things are so, then we're rationally pushed to conclude that there must be at least one self-existent being to explain why there are dependent beings.
1. Setup: Terminology
1.1 Dependent beings: a being whose existence is accounted for by the causal activity of other beings
1.2 Self-existent beings: beings whose existence is self-explanatory, or accounted for by their own inner nature
1.3 The Principle of Sufficient Reason (PSR): There must be an explanation for (a) the existence of every being, and (b) of every positive fact whatsoever, either in terms of something else or in terms of its own inner nature.
2. The Argument:
2.1 (1) Either everything is a dependent being, or there is a self-existent being.
2.1 (2) Not everything is a dependent being.
2.3 (3) Therefore, there is a self-existent being.
2.4 The argument is valid, since it has the valid argument form of Disjunctive Syllogism ((1) P or Q, (2) Not-P; therefore, (3) Q)
2.5 So, if the premises are both true, the conclusion follows of necessity.
2.6 So what is the evidence for the premises?
3. The Case for Premise 1: There can be no being that has no explanation at all (i.e., no explanation in terms of other beings, and no explanation in terms of its own nature)
3.1. Premise 1 states that either all beings are dependent, or there is at least one self-existent being.
3.2 But at first glance, at least, this seems false. For notice that there seem to be at least three types of beings that there could be
3.2.1 beings explained by one or more other beings
3.2.2 beings explained by nothing
3.2.3 beings explained by their own nature – self-explanatory beings
3.3 But the argument we’re discussing assumes that the second type of being is impossible
3.4 Why think that? If it’s wrong about that, then the argument doesn’t work
3.5 Answer: it assumes PSR
3.5.1 If the second type of being could exist, then it would have no explanation whatsoever for why it exists – it just does, and that’s all there is to say about it
3.5.2 But PSR says that everything has an explanation for why it exists, either in terms of something else or in terms of its own inner nature.
3.5.3 Thus, if PSR is true, then there can be no such beings.
3.6 Thus, PSR, if true, rules out this second type of being, and in this way, PSR supports premise (1).
4. The Case for Premise 2: Dependent beings can’t be accounted for in terms of just other dependent beings, no matter how many
4.1 The reason is not because every series of dependent beings must have a temporal "first" being to cause the others.
4.1.1 There are other versions of the cosmological argument that reason in that way.
4.1.2 But this version of the argument allows that a beginningless series of dependent beings is possible in principle
4.2 The real reason:
4.2.1 It's because, even if the series of dependent beings goes back forever, the existence of the series of dependent beings would itself be just another dependent being.
4.2.2 But if so, then by PSR(a), it too would need an explanation or sufficient reason for why it exists, and PSR says it must have one before we can legitimately stop our quest of explanations.
4.2.3 But even if the series of dependent beings isn't itself a being, the existence of the series of dependent beings is a positive fact or state of affairs.
4.2.4 But if so, then by PSR(b), it, too, would need an explanation for why it obtains.
4.2.5 Another way to think of it: even if there is an infinite series of dependent beings that goes back through eternity, we would still need an explanation for why there have always been dependent beings (as opposed to there being nothing).
4.2.6 Thus, no matter which way you slice it, dependent beings are inherently incapable of accounting for their own existence.
5. Conclusion:
5.1 The cosmological argument from contingency is logically valid; so if the premises are true, the conclusion follows of logical necessity.
5.2 Furthermore, there is a good prima facie case for the premises, as we've just seen
5.2.1 Premise 1 is supported by PSR, which rules out the existence of brute facts, i.e., beings that have no explanation for why they exist.
5.2.2 Premise 2 is supported by the apparent fact that dependent beings are inherently incapable of accounting for/explaining themselves.
5.3 If all these things are so, then we're rationally pushed to conclude that there must be at least one self-existent being to explain why there are dependent beings.
Two Helpful Overviews of the Design Argument
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