Deductive Vs. Inductive Arguments: Cosmological and Design

Theism is the belief in the existence of the omnipotent, omnipresent and benevolent being. This being's (debated) existence reveals the difference between religion and philosophy. While religion is based on faith, philosophy is rooted in reason and evidence. Philosophical beliefs are often stronger because where one might lose faith, a good argument persists. These arguments for God's existence take two forms: deductive and inductive. A deductively valid argument is one in which the truth of the premises – if they are, in fact, true – guarantees the conclusion. Consequently, deductive arguments are truth-preserving; nothing new is logically introduced in the conclusion because the truth of the conclusion is founded in the truth of the premises. This turns out to be both the weakness of the deductive argument and what separates it from an inductive one.

An inductive argument, on the other hand, is one which gives good grounds for its conclusion without being truth-preserving and without guaranteeing its truth. It relies on the truth of its premises to introduce a new conclusion. An inductive argument usually takes one of three forms: from specific occurrences to generalizations, from past observations to predictions, and from observed examples to explanations of the unobserved.

Two of the main arguments in support of theism are the cosmological argument and the argument from design which are considered to be deductive and inductive respectively. Saint Thomas Aquinas’s cosmological argument is deductive because it relies on true premises to yield a conclusion that is true, so long as the premises are true. Aquinas’s premises state that everything is either dependent (A) or self-existent (B) and not everything is dependent (not A). Therefore, the conclusion states that is a self-existent being (∴B). This deductive argument’s structure isIf A or BNot A∴BThe conclusion (B) lies within the first premise (A or B), thus the truth of the premise is preserved in the conclusion. This affirms the cosmological argument as a deductive argument not only because it is built on premises contained within the conclusion, but also because nothing new is introduced. Paley’s argument by design is inductive because it uses the premises to infer a new conclusion. While it does not guarantee its conclusion, the premises are easily established and support the explanation of the conclusion.

The teleological argument is an argument by analogy. In its initial case, the premises state that if one were to pitch upon a watch (or device capable of telling time), and the components of the watch just happen to go together so neatly that its excellent for telling time, it can be inductively inferred that the watch was designed to tell time by a watchmaker. When this analogy is applied to the biological domain, because this domain is much more complex than even the best watch, the being who created the biological domain is induced to be an omnipotent and omniscient designer.

The argument by design takes the third form of an inductive argument as it uses observed examples to explain the unobserved. As long as the premises are true, the argument introduces the new conclusion of the existence of an intelligent designer. While the cosmological argument is regarded as being a deductive argument, it ultimately rests on inductive reasoning. The deductive nature of the conclusion relies on the truth of the premises; however, both the argument’s premises rely on the Principle of Sufficient Reason. The PSR states that for any positive fact, there must be an explanation – or perhaps more applicable, for every being, there must be an explanation. The PSR rejects the idea of a being without an explanation because a being that exists has its presence as a positive fact. Thus the PSR affirms the first premise of the cosmological argument that states everything is either explained by other beings or the nature of the being itself. Rowe argues that the PSR also explains the second premise of the argument as well. The PSR states that in the set of all dependent event that ever occurred, every event had to have a reason.

However, the PSR also requires that the infinite series must have a first cause or at least an explanation external to the series: a self-existent being. Because the PSR is not a necessary truth formed from absolutely true premises, its truth, like all science, relies on induction. Because the PSR explains the premises of the cosmological argument, and the PSR is an inductive argument, the deductive cosmological argument in addition to the already inductive argument by design, ultimately rest on inductive reasoning.Explain why in Paley's inductive watch-maker argument, the reasoning can't start with the assumption that the thing he "pitches" on when walking across the "heath" is a watch. Why would such an assumption fatally weaken Paley's inductive argument to the best explanation of the ends/means purposive appearance of biological organisms and their parts?

Paley opens his inductive watch-maker argument with the assumption that he “pitches” upon a watch. However, we cannot use “a pocket or wrist timepiece” as the definition of the watch, but rather we must define a watch as a thing one can use to tell time. Using the standard definition of a watch undermines the inductive nature of the argument. There are many things in nature that can be used to tell time: the sun, the tides, the rings of trees; but a watch, as we know it, is a man-made artifact. The standard definition is a necessary truth, thus any argument utilizing it as a premise is a deductive argument. In this argument by analogy, the watchmaker’s existence is a new fact that Paley is trying to introduce, and therefore must be external to the premises. For this reason, the argument must be inductive, because starting with the assumption that the thing Paley pitches on when walking across the heath is a pocket or wrist timepiece, establishes the watchmaker's existence in the premises rather than proving it in the conclusion. Not only was it essential to the inductive nature of the argument for Paley to not define the watch as a timepiece, but also it also strengthened its conclusion. More specifically than definining the watch as a thing one can use to tell time, Paley goes on to describe the watch as “several parts [that] are framed and put together for a purpose”.

The components that make up the watch, just happen to work together so neatly that its excellent for telling time, so much so that it can be inductively infered that the watch was crafted specifically for the purpose of telling time. Unlike with the standard watch definition, these premises do not rely on the existence of a watchmaker, but rather lead to such a conclusion. Each successive component description bolsters the inductive argument. Each coil, fusee, and wheel included increases the complexity of the machine, and as a result, the intelligence and skill of the watchmaker must be that much greater.

On the other hand, presenting the watch as a singular object discreddits the watchmaker’s meticulous craftsmanship. When this analogy is applied to the biological domain, this complexity increases exponentially to such a degree that the creator of the biological domain must be omniscient and omnipotent. For instance, the number of base pairs in the human genome is a multitude of factors greater than the number of diamond-tipped teeth on all the gears inside a Rolex. Additionally, this inductive argument strives to use observed examples to explain the unobserved. In inductive arguments, because the conclusion is not guaranteed, the most likely explanation for the unobserved is usually the best. In the case of the watch, with each inclusion of complex machinery, counterexamples to the watchmaker's existence decrease in likelihood. For example, if the singular object of a watch were to spontaneously appear, it could be explained in the same manner as one atom of Uranium-238 emitting an alpha particle and another not. However, once the complexity of the watch is revealed, it is significantly less likely that a hunk of iron ore was struck by lightning in the presence of carbon to form stainless steel and a stream eroded away the steel in the shape of a watch back. Paley argues that due to the complexity, precision, and harmony of all the components, an intellegent designer is apparent. Paley opening his argument by pitching upon a watch would fatally weaken it by both subverting the inductive nature of the argument and challenging the omnipotence and omniscience of the being that Paley is trying to prove the existence of. Firstly, by Paley pitching upon a timepiece, the existence of watch’s designer is necessary and the argument becomes deductive. This is unsatisfactory to Paley because the guarantee of an intelligent designer does not lead to the inferred conclusion of a theistic god. Additionally, by ignoring the composite nature of the watch, Paley would deconstruct the analogy’s application to the biological domain and subsequently dissociate the intelligent watch designer and a theistic god.

Finally, viewing the watch as a uniform object increases the plausibility of counterexamples to Paley’s inductive argument. As a result, pitching upon a watch as a collection of components specialized to tell time is the superior method to rationalize the ends/means and purposive appearance of biological organisms and their parts.