Geologic Explanation:Thinking Like a

Geologist

Geologic Explanation:Thinking Like a

GeologistPhilosophical Perspectivesfrom Robert Frodeman and

Carol E. Cleland

Philosophical Perspectivesfrom Robert Frodeman and

Carol E. Cleland

Uniformitarianism interprets the past with the present in order to achieve the goal of extrapolation.

Actualism constrains explanation with the laws of chemistry and physics.

Temporal Reasoning follows “Steno’s Law of Superposition ” and “Walther’s Law of Facies.”

Punctuated Equilibrium contrasts with Gradualism as the mode and tempo of change.

Classical Principles of Geologic Thinking

Thinking Like a Geologist: Sources

Thinking Like a Geologist: Sources

“Geological reasoning: Geology as an interpretive and

historical science”Robert Frodeman, 1995

“Common cause explanationand the search for a smoking

gun”Carol E. Cleland, 2013

“Geological reasoning: Geology as an interpretive and

historical science”Robert Frodeman, 1995

“Common cause explanationand the search for a smoking

gun”Carol E. Cleland, 2013

Belief in a universal methodology is one such danger.

Understanding science in context overcomes this danger; for example, how [geologists] think.

An unrealistic understanding of science presents dangers.

Frodeman 1995

Self-awareness of thinking helps scientists do their work.

Geology models the nature of thinking within the sciences and within everyday life better than physics.

There is no science cookbook with recipes for infallible answers.

Frodeman 1995

Uncertainties and complexities abound.

Data are incomplete.

Reasonable assumptions fill the gaps.

Decisions require scientific and ethical judgment (nuclear power, global warming).

Frodeman 1995

“Analytic” school emphasizes concern for the natural world and builds upon logic and facts presumed independent of theory.

In the analytic school, science consists of a single set of logical procedures applicable to all fields. All science reduces to physics, and promises precise, reliable prediction.

Two Schools of PhilosophyThe Analytic

Frodeman 1995

“Continental” school emphasizes concern for cultural and personal phenomena. It depends upon narrative (story) to give meaning to the whole from its parts and meaning to the parts from the whole.

Science may be a powerful tool, but it is not the only way to know reality; “the” scientific method is a myth.

The theoretic assumptions that the scientist brings to his or her work—what counts as significant, what work is worth doing—structure to one degree or another all that is examined, seen, and reported.

Two Schools of PhilosophyThe Continental

Frodeman 1995

Story subsumes logic.

Falsification (Popper) and Paradigm Shifts (Kuhn) refute naïve inductivism.

Conceiving and acting shape thinking and perception. 

Discovery of “Deep” Time (Hutton’s “no vestige of a beginning—no prospect of an end”) has become a reliable truth.

Limits of the Analytic School:

Frodeman 1995

The Challenges to Geology

Incomplete data, poor resolution, lack of experimental control, immense spans of time, problematical direct observations:

Understanding cultural phenomena (literature) faces similar challenges. Frodeman 1995

The landscape is a text with chapters written in stone.

Geologists “read” rocks and landscape. They decipher the earth as text.

The unconformity , for example, at Siccar Point

Frodeman 1995

Interpretive and Historical Practices

Historical entities are defined through time: the Cascadia Subduction Zone, the Grand Canyon of the Colorado River, and the Tibetan Plateau.

Identity and property are contingent upon history.

Historical entities, not “natural kinds,” predominate and central subjects

organize geologic inquiry.Frodeman 1995

The past is explainable; the future, uncertain.

The goal in geology is not primarily to identify general laws, but rather to chronicle the particular events that occurred at a given location (at the outcrop, in the region, or across the entire planet).

This means that hypotheses are not testable in the way they are in the experimental sciences.

Frodeman, 1995

Interpretive inquiry recycles understanding. . . as depicted on a concept map.

New thinking suggested by the parts revises the conception of the whole.

New understanding of the whole improves knowledge of the parts.

Tools lead to new conceptions; new conceptions suggest new

tools.Frodeman 1995

“Common cause explanation and the search for a smoking gun” Carol E. Cleland, 2013

“Common cause explanation and the search for a smoking gun” Carol E. Cleland, 2013

OVERVIEW

Myths about the scientific Method.

Classical experimental science and prototypical historical science: two different but equally rational and objective patterns of evidential reasoning.

How evidence acquired through field work justifies historical hypotheses: Common cause explanation and the search for a “smoking gun”.

OVERVIEW

Myths about the scientific Method.

Classical experimental science and prototypical historical science: two different but equally rational and objective patterns of evidential reasoning.

How evidence acquired through field work justifies historical hypotheses: Common cause explanation and the search for a “smoking gun”.

Part IPart I

Cleland, 2013

Myths about the Scientific method

Myths about the Scientific method

Inductivism: Scientists prove theories and hypotheses by a logical process of induction.

Inductivism: Scientists prove theories and hypotheses by a logical process of induction.

Cleland, 2013

Myths about the Scientific method

Myths about the Scientific method

Falsificationism: Scientists falsify theories and hypotheses by using empirical evidence to refute them.

Falsificationism: Scientists falsify theories and hypotheses by using empirical evidence to refute them.

Cleland, 2013

The Logic of PredictionThe Logic of Prediction

Basic ConceptsBasic Concepts

1. Hypothesis (H): (All C’s are E’s)

2. Test Implication (I):(If x is a C, then x is an E.)

3. Test Condition (C):

4. Prediction (E):

1. Hypothesis (H): (All C’s are E’s)

2. Test Implication (I):(If x is a C, then x is an E.)

3. Test Condition (C):

4. Prediction (E):

“Toy” Example“Toy” Example

All copper expands when heated.

If sample of copper #4 is heated, then it will expand

(Heating copper sample #4)

(Copper sample #4 will expand)

All copper expands when heated.

If sample of copper #4 is heated, then it will expand

(Heating copper sample #4)

(Copper sample #4 will expand) Cleland, 2013

The Logic of Evaluating the Results of an Experiment

The Logic of Evaluating the Results of an Experiment

Successful Prediction1. If H, then I2. IC. H

Logical Fallacy: “affirming the consequent”. (This is just another version of the problem of induction.)

Successful Prediction1. If H, then I2. IC. H

Logical Fallacy: “affirming the consequent”. (This is just another version of the problem of induction.)

Cleland, 2013

The Logic of Evaluating the Results of an Experiment

The Logic of Evaluating the Results of an Experiment

Failed Prediction1. If H, then I2. Not-IC. Not-H

Valid Argument Form: “denying the consequent”.(This explains the appeal of falsificationism.)

Failed Prediction1. If H, then I2. Not-IC. Not-H

Valid Argument Form: “denying the consequent”.(This explains the appeal of falsificationism.)

Cleland, 2013

The Terrible Truth about Falsification

The Terrible Truth about Falsification

The form of the first premise in the previous argument is:

If H and A, then I(where ‘A ’ stands for a set of auxiliary assumptions {a1, a2, …, an} about other conditions, known and unknown, about the actual experimental situation.)

The form of the first premise in the previous argument is:

If H and A, then I(where ‘A ’ stands for a set of auxiliary assumptions {a1, a2, …, an} about other conditions, known and unknown, about the actual experimental situation.)

Cleland, 2013

The Terrible Truth about Falsificationism (continued)The Terrible Truth about Falsificationism (continued)

This changes the form of the argument to:

1. If H and {a1, a2, …, an}, then I

2. Not-I3. Not-(H and {a1, a2, …, an})4. Not-H or not-{a1, a2, …, an} 5. Not-H or not-a1 or not-a2 or

… or not-an

(by De Morgan’s theorem)

This changes the form of the argument to:

1. If H and {a1, a2, …, an}, then I

2. Not-I3. Not-(H and {a1, a2, …, an})4. Not-H or not-{a1, a2, …, an} 5. Not-H or not-a1 or not-a2 or

… or not-an

(by De Morgan’s theorem) Cleland, 2013

The Terrible Truth about Falsificationism (continued)The Terrible Truth about Falsificationism (continued)

From a logical standpoint, no observation (whether experimental or in the field), can conclusively falsify a hypothesis. For it is always possible to salvage the hypothesis in the face of a failed prediction by denying an auxiliary assumption.

From a logical standpoint, no observation (whether experimental or in the field), can conclusively falsify a hypothesis. For it is always possible to salvage the hypothesis in the face of a failed prediction by denying an auxiliary assumption.

Cleland, 2013

Conclusion Conclusion

Neither inductivism nor falsificationism provides a satisfactory account of any scientific practice; the scientific method of yore is a myth.

Neither inductivism nor falsificationism provides a satisfactory account of any scientific practice; the scientific method of yore is a myth.

Cleland, 2013

Part IIPart II

Differences in the methodology of classical experimental science and

prototypical historical, natural science:

Is historical natural science methodologically inferior to

experimental science?

Differences in the methodology of classical experimental science and

prototypical historical, natural science:

Is historical natural science methodologically inferior to

experimental science?

Cleland, 2013

The structure of Classical Experimental

Science

The structure of Classical Experimental

Science Focus: Is on a single (sometimes complex)

hypothesis which typically has the form of a universal generalization (All C’s are E’s).

Central Research Activity: Consists in repeatedly bringing about the test conditions specified by the hypothesis and controlling for extraneous conditions that might be responsible for false positives and false negatives.

Focus: Is on a single (sometimes complex) hypothesis which typically has the form of a universal generalization (All C’s are E’s).

Central Research Activity: Consists in repeatedly bringing about the test conditions specified by the hypothesis and controlling for extraneous conditions that might be responsible for false positives and false negatives.

Cleland, 2013

The structure of Prototypical Historical

Science

The structure of Prototypical Historical

Science Focus: Is on proliferating multiple, rival

hypotheses to explain a puzzling body of traces of past events (data) encountered in field work.

Central Research Activity: Consists in searching for a ‘smoking gun’ a trace(s) that sets apart one or more hypotheses as providing a better explanation for the body of traces thus far acquired than the others.

Focus: Is on proliferating multiple, rival hypotheses to explain a puzzling body of traces of past events (data) encountered in field work.

Central Research Activity: Consists in searching for a ‘smoking gun’ a trace(s) that sets apart one or more hypotheses as providing a better explanation for the body of traces thus far acquired than the others.

Cleland, 2013

A Case StudyThe Alvarez Hypothesis

A Case StudyThe Alvarez Hypothesis

Two-pronged hypothesis: 1) impact; 2) extinction.

Initially many different explanations for the end-Cretaceous mass extinction: pandemic, evolutionary senescence, climate change, supernova, volcanism, and meteorite Impact.

Discovery of an iridium anomaly (“smoking gun”) in K-T boundary sediments narrowed it down to two possibilities: volcanism and meteorite impact. Discovery of extensive quantities of a rare form of shocked mineral subsequently cinched the case for impact over volcanism.

Two-pronged hypothesis: 1) impact; 2) extinction.

Initially many different explanations for the end-Cretaceous mass extinction: pandemic, evolutionary senescence, climate change, supernova, volcanism, and meteorite Impact.

Discovery of an iridium anomaly (“smoking gun”) in K-T boundary sediments narrowed it down to two possibilities: volcanism and meteorite impact. Discovery of extensive quantities of a rare form of shocked mineral subsequently cinched the case for impact over volcanism.Cleland, 2013

A Case Study: The Alvarez Hypothesis (cont)A Case Study: The Alvarez Hypothesis (cont)

Paleontologists weren’t convinced: They agreed that there had been a meteorite impact but many doubted that it caused the end-Cretaceous extinctions.

The discovery of extensive pertinent fossil evidence (especially small organisms such as foraminifera and ammonites, and fern spores and angiosperm pollin) on either side of the K-T boundary was pivotal in changing their minds, providing the needed smoking gun for the second prong (mass extinction) of the hypothesis.

Paleontologists weren’t convinced: They agreed that there had been a meteorite impact but many doubted that it caused the end-Cretaceous extinctions.

The discovery of extensive pertinent fossil evidence (especially small organisms such as foraminifera and ammonites, and fern spores and angiosperm pollin) on either side of the K-T boundary was pivotal in changing their minds, providing the needed smoking gun for the second prong (mass extinction) of the hypothesis. Cleland, 2013

The Evaluation of Historical Hypotheses The Evaluation of Historical Hypotheses

Grounded in explanatory power:

Hypotheses are accepted and rejected in virtue of their power to explain (vs. predict) puzzling bodies of traces discovered through field work.

The Alvarez hypothesis explains an otherwise puzzling association (correlation) among traces better than any of its rivals. It is for this reason that it is viewed as ‘confirmed’ and its rivals are no longer seriously entertained by scientists.

Grounded in explanatory power:

Hypotheses are accepted and rejected in virtue of their power to explain (vs. predict) puzzling bodies of traces discovered through field work.

The Alvarez hypothesis explains an otherwise puzzling association (correlation) among traces better than any of its rivals. It is for this reason that it is viewed as ‘confirmed’ and its rivals are no longer seriously entertained by scientists.

Cleland, 2013

Part IIIPart III

Common cause explanationCommon cause explanation

Cleland, 2013

Common Cause explanationCommon Cause explanation

Reichenbach’s Principle of the Common Cause: seemingly improbable associations (correlations or similarities) among traces are best explained by reference to a common cause.

C

Presupposes that the temporal structure of causal relations in our universe is such that most (not all) events form causal forks opening from past to future (leave many traces in the future).

Reichenbach’s Principle of the Common Cause: seemingly improbable associations (correlations or similarities) among traces are best explained by reference to a common cause.

C

Presupposes that the temporal structure of causal relations in our universe is such that most (not all) events form causal forks opening from past to future (leave many traces in the future).

E1

E2

E3

E4

Cleland, 2013

The Asymmetry of OverdeterminationThe Asymmetry of Overdetermination

A time asymmetry of causation: Most local events & structures overdetermine their past causes (because the latter typically leave extensive and diverse effects)and underdetermine their future effects (because they rarely constitute the total cause of an effect)

Much easier to infer an ancient volcanic eruption than a near future volcanic eruption.

A time asymmetry of causation: Most local events & structures overdetermine their past causes (because the latter typically leave extensive and diverse effects)and underdetermine their future effects (because they rarely constitute the total cause of an effect)

Much easier to infer an ancient volcanic eruption than a near future volcanic eruption.

Cleland, 2013

An illustration: The colors of dinosaursAn illustration: The colors of dinosaurs

Asym of OD Asserts that the present is filled with overdetermining traces of the past; hence one can never completely rule out finding a

“smoking gun” for any scientific hypothesis about the past. The methodology of historical field work is based

upon

this possibility.

Asym of OD Asserts that the present is filled with overdetermining traces of the past; hence one can never completely rule out finding a

“smoking gun” for any scientific hypothesis about the past. The methodology of historical field work is based

upon

this possibility.

Cleland, 2013

ConclusionsConclusions

1. Historical Scientists exploit the overdetermination of the past by the localized present by searching for a common cause (“smoking gun”) to discriminate among competing hypotheses; the asymmetry of overdetermination guarantees there are likely to be many such telling traces. The problem is recognizing them for what they represent.

1. Historical Scientists exploit the overdetermination of the past by the localized present by searching for a common cause (“smoking gun”) to discriminate among competing hypotheses; the asymmetry of overdetermination guarantees there are likely to be many such telling traces. The problem is recognizing them for what they represent. Cleland, 2013

ConclusionsConclusions

2. The methodology of historical science is different from that of classical experimental science but it is not inferior; each practice is designed to exploit the differing information that nature puts at its disposal.

2. The methodology of historical science is different from that of classical experimental science but it is not inferior; each practice is designed to exploit the differing information that nature puts at its disposal.

Cleland, 2013

Cleland ReferencesCleland References “Common cause explanation and the search for a smoking gun” in Baker, V.

(ed.), 125th Anniversary volume of the Geological Society of America (forthcoming).

“Prediction and Explanation in Historical Natural Science,” British Journal of Philosophy of Science 62 (2011), 551-582.

“Philosophical issues in natural history and its historiography” in Tucker, A. (ed.), Blackwell Companions to Philosophy: A Companion to the

Philosophy of History and Historiography. Oxford: Blackwell Pub. (2009), pp. 44-62.

“Methodological and Epistemic Differences Between Historical Science and Experimental Science,” Philosophy of Science 69, (2002), pp. 474-

496. “Historical science, experimental science, and the scientific method,” Geology

29, (2001), pp. 987-990.

“Common cause explanation and the search for a smoking gun” in Baker, V. (ed.), 125th Anniversary volume of the Geological Society of America (forthcoming).

“Prediction and Explanation in Historical Natural Science,” British Journal of Philosophy of Science 62 (2011), 551-582.

“Philosophical issues in natural history and its historiography” in Tucker, A. (ed.), Blackwell Companions to Philosophy: A Companion to the

Philosophy of History and Historiography. Oxford: Blackwell Pub. (2009), pp. 44-62.

“Methodological and Epistemic Differences Between Historical Science and Experimental Science,” Philosophy of Science 69, (2002), pp. 474-

496. “Historical science, experimental science, and the scientific method,” Geology

29, (2001), pp. 987-990.