3.1 Explaining the Natural World

3.1.1 Aristotle: Searching for Causes

Note: Portions of the following material on Aristotle are adapted from information in The Philosophy Pages by Garth Kemerling and is licensed under a Creative Commons Attribution-ShareAlike 3.0

Aristotle (384-322 BCE) was the greatest and most influential student of Plato, whom we met in our introduction to rationalism in the Epistemology unit. Aristotle’s extensive works are marked by his gradual philosophical departure from Plato’s teachings of abstract thought about the realm of forms.

For Aristotle, logic is the means by which we come to know anything. Human knowledge seeks to establish that things have features of a certain kind. In Aristotle’s system of thought, propositions in the subject-predicate form are the primary expressions of truth about the world; they convey features or properties inherent in individual substances. He believed his logical scheme accurately represented the true nature of reality. By beginning with simple descriptions of particular things, he thought it possible to eventually assemble the information needed for a comprehensive view of the world. Aristotle’s formal rules for correct reasoning — the basic principles of categorical logic — were universally accepted by Western philosophers until the nineteenth century.

Aristotle believed that universal truths could be known from particular things by way of induction. However, he did not consider knowledge acquired by induction to be scientific knowledge. Nevertheless, induction was a necessary preliminary to the main business of scientific inquiry, providing the primary premises required for scientific demonstrations.

Axioms, the self-evident first principles for which no proof is required, according to Aristotle, both necessitate and explain the truths of science.

Applying the principles developed in his logical treatises, Aristotle offered a general account of the operation of individual substances in the natural world. He drew a significant distinction between these two sorts of things:

• those that move only when moved by something else, and
• those that are capable of moving themselves.

Aristotle proposed a proper description of things of each sort, and he also attempted to explain why they function as they do. In considering bodies and their externally-produced movement, Aristotle shaped his discussion of physical science with three crucial distinctions:

1. Because of the difference in their origins, different accounts need to be offered for the functions of natural things and those of artifacts.
2. Clear distinction is needed between the basic material and the form, which jointly constitute the nature of any individual thing.
3. Recognition is required of the difference between things as they are and things considered in light of their ends or purposes.

With these distinctions in mind, Aristotle proposed four explanatory factors, or causes, required for having knowledge and understanding of things in the natural world:

The material cause is the basic stuff out of which the thing is made. The material cause of a house, for example, would include all the building materials. They are all part of an explanation of the house because it could not exist unless they were present in its composition.

The formal cause is the pattern or essence with which these materials conform when assembled. The formal cause of our exemplary house would be the design and structure that might be called for in its drafted plans. This, too, is part of the explanation since the materials would be only a pile of rubble (or a different house) if they were not specified in this way.

The efficient cause is the agent or force immediately responsible for bringing the material and form together to produce the thing. In the case of our house, the efficient cause would include the carpenters, masons, plumbers, and other workers who used these materials to build the house in accordance with the plans for its construction. Clearly the house would not be what it is without their contribution.

The final cause is the end or purpose for which a thing exists. For our house, the final cause would be to provide shelter for human beings. This is part of the explanation of the existence of the house, because it would not have been built unless someone needed it as a place to live.

Aristotle’s philosophy of the natural world (what we would now refer to as “philosophy of science”) claims that the world is explained by searching out the causes of natural phenomena. He believed that all four types of causes are necessary elements in any adequate account of the existence and nature of things. The absence or modification of any one of them would result it the existence of a different sort of thing. An explanation that includes all four causes completely captures the significance and reality of the thing itself.

Causation, the relationship between two events such that the first (the cause) brings about the second (the effect) has been ingrained in common thinking at least since Aristotle, though our modern conception of cause-and-effect is less complicated than Aristotle’s. As we have seen, however, the possibility of knowing that causal relationships actually exist was rejected by David Hume.

3.1.2 Bacon: Observation and Induction

Francis Bacon (1561-1626) was an Englishman with many intellectual passions: law; politics; literature; history; and philosophy, including topics related to acquiring knowledge of the natural world. Among his other viewpoints that were revolutionary for his times, Bacon took exception to the prevailing Aristotelian preference for deduction over induction as the certain path to knowledge. Further, Bacon rejected the conception of natural philosophy (science!) as an understanding of necessary causes.

Bacon was an empiricist who believed that acquiring knowledge of the natural world must proceed inductively:

• first, making recurring and exhaustive observations, collecting as many facts as possible,
• and then drawing conclusions that generalize the findings from specific observations.

His method — proceeding from copious observation to formulation of a theory — became a predominant method for doing science during Bacon’s own time and had influence for centuries that followed.

Objections to Bacon’s method for doing science include these criticisms:

• Induction does not bring the level of certainty we seek in science.
• There is no clarity as to when enough observation and investigation has occurred to finally arrive at a generalized conclusion.
• The slow and plodding pace at which the method proceeds does not accommodate the spontaneous and visionary process that often leads to new scientific knowledge.

A supplemental resource on Bacon’s use of induction is available at the end of this section.

Video

This video reinforces the important role that creative ideas  (i.e., spontaneity and vision) play in furthering scientific knowledge. It also serves as transition to the next topic.

3.1.3 Working from Hypotheses

Is moving from observations to formulating a theory the only method for doing science? As demonstrated in Adam Savage’s TED-Ed video, scientific progress often starts with imagination and creative ideas (hypotheses) that influence the direction for observations, fact gathering, and testing. The Hypothetico-Deductive (H-D) method (or simply “the hypothetical method”) is a different model for the process of scientific discovery.

The process involves formulation of a testable hypothesis that could conceivably be falsified by observable data. If an observation or a test does run contrary to the predictions of the hypothesis, then the hypothesis is falsified; it must be rejected or reformulated.

Falsification follows the valid argument form modus tollens from our Logic Unit, letting H=hypothesis, E=expected result:

If H, then E

not E

not H

On the other hand, if a test or observation does meet predicted expectations, this compatible outcome strengthens the hypothesis and lends it credibility, but it does not confirm it. Recall the fallacy of affirming-the-consequent from the Logic Unit; this fallacy is committed when the expected result (consequent) of an implication occurs and the arguer claims the antecedent to be true. The occurrence of the expected result cannot provide logical certainty. Some other hypothesis might be capable of creating the same result:

If H, then E

E

H

But expected results are steps forward. Every new test/observation found to meet expected results adds to the strength of the hypothesis. When no test is found to falsify the hypothesis, it may become accepted, at least tentatively, as a theory.

It’s important to point out that observations (empirically acquired facts) are not devalued by this method, they are essential, just a they are with inductive generalizations. Initial (or early) hypotheses (potential theories) may precede and set the direction for observations and experiments. The initial problem or question addressed by the hypothesis was most likely sparked initially by some observations.

In the next section, among other topics, we will look more closely at falsifiability and tentative acceptance of hypotheses and theories.

A supplemental resource on the scientific method is available at the end of this section.

3.1.4 Scientific Methods Summarized

Induction and Generalization

1. Accumulation of as many observed facts as possible concerning the topic under investigation.
2. Generalization from the particular observations that infer a general theory from accumulated particular facts.
3. Repeated accumulation of more particular facts to assess if the generalization continues to hold true. The more particular instances, the more confirmation and the higher the probability of the correctness of the generalization-based theory.

Hypothetical Method

The interplay of hypothesizing, observing and testing, reformulating hypotheses, and so forth, suggests that there may be no single, universal scientific method, especially one that might fit the multitude of scientific disciplines. Specific disciplines have particular steps and methods for doing science. There may not be a single, distinct, universal process. But as philosophers of science we might expect certain basic activities to take place.

1. Recognition/identification of a problem or question requiring investigation. This step probably involved prior empirical observations.
2. Proposal of a hypothesis that explains the problem or answers the question and is capable of being verified by empirical means.
3. Verification of the hypotheses through empirical activities including observations, experiments, or tests.
4. If any verification step falsifies the hypotheses, a return to step 2, a new hypothesis, is required.
5. If verification steps repeatedly support/strengthen the hypothesis, it may be accepted, at least tentatively, as a theory.

Supplemental Resources

Bacon

Scientific Method