Design Arguments for the Existence of God

Author: Thomas Metcalf
Category: Philosophy of Religion
Word count: 990

The universe, or some of the objects in it, exhibit order, complexity, efficiency, and perhaps purpose. Many everyday objects with those features—e.g., watches and houses—were intentionally designed. Should we conclude, therefore, that some of the “natural” objects in the universe, or the universe itself, was also intentionally designed? If so, that designer might be God.

1. The Arguments

The standard ‘Design’ or ‘Teleological’ arguments for theism hold that there is evidence of design in nature and that this is evidence for the existence of God.[1]

There are three general versions of this argument. ‘Biological Design Arguments’ claim that God designed some or all of the biological organisms in the universe.[2] ‘Physical Design Arguments’ (or ‘Cosmic Design’ arguments) claim that God designed something about the large-scale structure and contents of the universe, or its laws of nature, or the small-scale structure of its components.[3] ‘Fine-Tuning Arguments’ claim that God intentionally chose the physical laws, fundamental constants, and initial conditions of the universe so the universe would permit complex, biological life.[4]

2. The Evidence

Biological organisms arguably exhibit interesting order, complexity, and purpose: e.g., the human eye. By analogy, if you were to find and examine a camera lying in a field somewhere, you would be irrational to conclude that it had formed mindlessly and naturally. You should instead notice that it has many parts, each serving a particular purpose, working together for a valuable, general function. But of course the human eye also has many parts, each serving a particular purpose, working together for a valuable, general function.[5]

One version of these arguments holds that some biological systems exhibit ‘irreducible complexity.’ This occurs when some system would not be adaptive or useful unless all of its parts were present simultaneously.[6] As a simplified analogy, suppose that your immune system has two subsystems: a subsystem that detects and identifies invaders, and a subsystem that kills invaders and infected cells.[7] If your immune system lacked the first type of subsystem, then it would either not kill invaders, or it would also kill your own, healthy cells. If your immune system lacked the second type of subsystem, then it wouldn’t do anything to the invaders it detected. Only if both types are present is the immune system adaptive. But surely—the proponent of the argument insists—it’s extremely unlikely that both subsystems should have independently evolved at the same time. Yet, of course, God could have created them both at once, thereby creating a well-functioning immune system.

The physical universe itself, in the large scale, may also exhibit evidence of design.[8] Perhaps the planets’ orbiting their stars, and the probability-clouds of electrons, are orderly enough to remind us of the carefully-planned motion of mechanical systems inside a human-designed machine. Of course, someone might object that the planets are simply following the laws of conservation of angular momentum and gravity,[9] but the proponent of the physical design-argument can reply that laws of nature are also evidence of a designer.[10] Last, scientists generally agree that if certain features of the universe were slightly different— say, if gravity were somewhat stronger or weaker—then living beings like us would be physically impossible.[11] And there are allegedly very many other examples of laws, constants, and initial conditions that must be delicately balanced for life to exist. Yet here we are. So, the argument goes, either we got extremely lucky—perhaps as lucky as winning the lottery several times in a row[12]—or God “fine-tuned” the universe to permit life like us.

3. Objections

While design arguments have skilled defenders, most philosophers have not yet been persuaded.[13]

One potential problem with biological design arguments is that we know of a powerful mechanism that can mindlessly produce order, complexity, and purpose: the mechanism of evolution by natural selection.[14] This might even explain “irreducible complexity.”[15] For example, a species might evolve to have a simple immune-system in which the same system both identifies and attacks invaders; and then evolve, in addition, a second kind of subsystem, which only identifies invaders (thereby enhancing the power of the general immune system); and then evolve a third kind, which only attacks; and then cease to have the original system that does both.

Another potential problem with biological design arguments is that living creatures may exhibit evidence of “poor design.”[16] For example, human beings might have been better-designed if we didn’t use the same tube both to breathe and to swallow food. And we are vulnerable to several tragic, untreatable genetic diseases, such as Tay-Sachs disease,[17] which chiefly affects young children. Given the hypothesis of a divine designer who is much-more-intelligent than we, it is puzzling that some creatures exhibit poor design.

The philosopher David Hume challenged biological and physical design arguments in various ways. For example, he wondered whether God himself needs a designer, and whether mindless motion and laws might produce the order and complexity we observe. One might also ask how much we can conclude about a designer when we only have one universe to examine, and we have no track record of having observed universe-designers. And design arguments, in general, might better-support the hypothesis that there is an imperfect designer, or that there were many designers—both of which hypotheses are incompatible with traditional monotheism.[18]

Last, fine-tuning arguments have been critiqued by arguing that life-permission isn’t so surprising, even given the hypothesis of atheism. Maybe we live in a multiverse of universes with varying laws and constants; maybe there is a more-fundamental, simpler principle that generates a life-permitting set of further laws; and maybe we shouldn’t be surprised that we—living beings—live in a life-permitting universe.[19] How could it be otherwise?

4. Next Steps

Some philosophers endorse design arguments, but few of these philosophers believe that these arguments prove the existence of an omnipotent, omniscient, morally perfect God.[20] Therefore, to decide whether God exists, we must consider other arguments for theism, and weigh the evidence from design against any evidence against the existence of God that we might have.


[1] For landmark examples, see Aquinas (2006 [1265-1274]: Ia, 2, 3); Hume (1998 [1779]: Part 2); and Paley (2006 [1802]).

[2] Other than the items cited in the previous note, see Behe (1996) and Dembski (1998) for biological design-arguments.

[3] Swinburne (2004), Chapter 8.

[4] Collins (2012).

[5] Paley (2006 [1802]), Chapter 3.

[6] Behe (1996), pp. 130-31.

[7] Cf. Janeway et al. 2001.

[8] Hume (op. cit.), Part 2.

[9] Ibid.

[10] Swinburne (1968), p. 202.

[11] Collins (2012), §§ 2.2-2.4.

[12] For example, Collins (2012: § 2.3.2) argues that even the strength of gravity could not have varied by more than one part in 1060 and allowed the universe to permit life. If you have a one-in-108 chance of winning a lottery, then mathematically, to win that lottery seven times in a row (assuming no cheating and independent trials) is still more probable than ending up with just the right strength of gravity among 1060 possible strengths. And the strength of gravity is allegedly only one of the many constants that needed to be fine-tuned to permit life like us.

[13] See Bourget and Chalmers (2014), p. 476, for evidence that most philosophers have rejected arguments for the existence of God.

[14] See for example Dawkins (2015).

[15] Shanks and Joplin (1999).

[16] See Charles Darwin (1999 [1859]), Chapter 14. See also Gould (1980). Swinburne (1968, p. 201) notes that this may even be true in physical design-arguments

[17] Walker (2006).

[18] Hume (op. cit.).

[19] Collins (2012), §§ 5-7.

[20] Swinburne (1968), p. 199. Collins (2012) himself presents his argument as evidential.


Aquinas, Thomas. Summa Theologiae, Questions on God, ed. Leftow, Brian and Davis, Brian. Cambridge, UK: Cambridge University Press, 2006 [1265-1274].

Behe, Michael J. Darwin’s Black Box: The Biochemical Challenge to Evolution. New York, NY: Touchstone, 1996.

Bourget, David and Chalmers, David J. “What do Philosophers Believe?” Philosophical Studies 170 (3) (2014): 465-500.

Collins, Robin. “The Teleological Argument,” in Craig, William Lane and Moreland, J. P. (eds.), The Blackwell Companion to Natural Theology (Malden, MA and Oxford, UK: Blackwell, 2012), pp. 202-281.

Darwin, Charles. The Origin of Species. New York, NY: Bantam Dell, 1999 [1859].

Dawkins, Richard. The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe without Design. New York, NY: W. W. Norton & Company, Inc., 2015.

Dembski, William A. The Design Inference: Eliminating Chance through Small Probabilities. New York, NY: Cambridge University Press, 1998.

Gould, Stephen Jay. The Panda’s Thumb: More Reflections in Natural History. New York, NY and London, UK: W. W. Norton & Company, Inc., 1980.

Hume, David. Dialogues Concerning Natural Religion, 2nd ed., ed. Popkin, Richard H. Indianapolis, IN: Hackett Publishing Co., 1998 [1779].

Janeway, Charles et al. Immunobiology, 6th ed. New York, NY: Garland Science Publishing, 2005.

Paley, William. Natural Theology or Evidences of the Existence and Attributes of the Deity. New York, NY: Oxford University Press, 2006 [1802].

Shanks, Niall and Karl H. Joplin. “Redundant Complexity: A Critical Analysis of Intelligent Design in Biochemistry.” Philosophy of Science 66 (2) (1999): 268-82.

Swinburne, Richard. “The Argument from Design.” Philosophy 43 (165) (1968): 199-212.

Swinburne, Richard. The Existence of God, 2nd ed. New York, NY: Oxford University Press, 2004.

Walker, Julie. Tay-Sachs Disease. New York, NY: Rosen Publishing Group, 2006.

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The Fine-Tuning Argument for the Existence of God by Thomas Metcalf

About the Author

Tom is an assistant professor at Spring Hill College in Mobile, AL. He received his PhD in philosophy from the University of Colorado, Boulder. He specializes in ethics, metaethics, epistemology, and the philosophy of religion. Tom has two cats whose names are Hesperus and Phosphorus. Website:


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