Source Count: 12 | Weighted Score: 21 | Source Confidence: [2/5] | Primary Tier: 1 | Last Updated: March 11, 2026
Keywords: philosophy of biology, species concept, biological species, teleology, function, natural selection, adaptation, reductionism, gene-centered, units of selection, fitness, essentialism, population thinking, individuation, biological explanation, Sober, Hull, Godfrey-Smith
Category Tags: philosophy-meaning, philosophy-of-biology, species-concept, teleology, natural-selection, function, biological-explanation
Cross-References: P_3_05 — Philosophy of Science · R_1_12 — Evolutionary Theory · B_4_06 — Classification

QUICK SUMMARY

The philosophy of biology examines the conceptual foundations, explanatory structures, and ontological commitments of the biological sciences — asking questions that biology itself presupposes but does not typically address. Its central concerns include: (1) What is a species? — the "species problem" has generated over 20 competing definitions (biological species concept, phylogenetic species concept, morphological species concept, etc.), raising fundamental questions about whether species are natural kinds (like chemical elements) or historical individuals (like particular organisms); (2) What is biological function? — when we say the heart's function is to pump blood, are we making a causal claim (the heart's pumping explains why hearts were selected for — the etiological/selected effects theory, Wright 1973, Millikan 1984), or a dispositional claim (hearts contribute to pumping in the current system — the causal role theory, Cummins 1975)?; (3) What is the unit of selection? — is natural selection operating primarily on genes (Dawkins's selfish gene), individual organisms (Darwin's original view), groups (Wynne-Edwards, revived by D.S. Wilson), or some combination?; (4) Is biology reducible to physics and chemistry? — or does it require its own autonomous explanatory principles (emergence, organization, information)?; and (5) Teleology — biological organisms appear goal-directed (purposive) — how should science understand this apparent purposiveness without invoking conscious design?

1. VERIFIED CLAIMS (Tier 1 — Peer-Reviewed / Established)

1.1 The Species Problem

• There is no universally accepted definition of "species":
• Biological Species Concept (BSC — Ernst Mayr, 1942): species are groups of actually or potentially interbreeding natural populations reproductively isolated from other such groups
• Strengths: intuitive, ties species to a clear biological mechanism (reproductive isolation)
• Weaknesses: inapplicable to asexual organisms, fossils, and allopatric populations (geographically separated populations where reproductive isolation cannot be tested)
• Phylogenetic Species Concept (PSC — Cracraft, 1983): the smallest diagnosable cluster of individuals within which there is a parental pattern of ancestry and descent
• Morphological Species Concept: species defined by morphological similarity — the oldest and most practically used approach, but criticized for being subjective
• Ecological Species Concept (Van Valen, 1976): species as lineages occupying an adaptive zone
• Species as Individuals (Ghiselin, 1974; Hull, 1978): species are not classes (natural kinds) but historical individuals — spatiotemporally bounded, unique entities. Just as an individual organism is not a "type" of thing but a particular thing, so is Homo sapiens — a particular lineage, not a universal category

1.2 Biological Function

• Etiological/Selected Effects Theory (Wright, 1973; Millikan, 1984; Neander, 1991): the function of a trait is the effect for which it was selected by natural selection — the heart's function is to pump blood because past hearts that pumped blood were selected for, causing present hearts to exist
• This account ties function to evolutionary history and grounds normativity (a heart that fails to pump is malfunctioning — it's not doing what it was selected to do)
• Causal Role Theory (Cummins, 1975): the function of a component is its contribution to a capacity of the containing system — the heart's function is pumping blood because that's how it contributes to the circulatory system's capacity. No appeal to history required
• Criticism: too liberal — the sound the heart makes "contributes" to the system's noise-making capacity, but we wouldn't say the heart's function is to make noise

1.3 Units of Selection

• Gene-centered view (George C. Williams, 1966; Richard Dawkins, The Selfish Gene, 1976): the gene is the fundamental unit of selection — organisms are "vehicles" or "survival machines" for replicating genes
• Organism-centered view (Darwin; many contemporary biologists): individual organisms are the primary targets of natural selection
• Group selection (revived by D.S. Wilson and E.O. Wilson): selection can operate on groups of organisms — groups with cooperative members may outcompete groups of selfish individuals
• Multi-level selection (Okasha, 2006): selection operates at multiple levels simultaneously (gene, organism, group) and which level predominates depends on the biological context

2. CREDIBLE CLAIMS (Tier 2 — Academic / Debated but Supported)

2.1 Reductionism vs. Autonomy

• Can biology be reduced to physics and chemistry?
• Reductionists (e.g., Rosenberg): in principle, all biological phenomena are ultimately physical-chemical processes; biological concepts are heuristics
• Autonomists (e.g., Mayr, Kitcher, Mitchell): biology requires its own explanatory levels — concepts like "fitness," "adaptation," "species," and "function" are not reducible to physical descriptions without explanatory loss
• Most contemporary philosophy of biology occupies a middle ground: explanatory pluralism — biology legitimately uses explanations at multiple levels (molecular, organismal, populational, ecological)

2.2 Teleology and Natural Selection

• Darwin's theory resolves the problem of biological teleology by providing a mechanism (natural selection) that produces the appearance of design without actual design:
• Natural selection operates as a blind process — no foresight, intention, or conscious purpose — yet produces organisms that appear exquisitely adapted to their environments
• Some philosophers (e.g., Dennett, 1995) argue natural selection is "the single best idea anyone has ever had" precisely because it explains apparent purposiveness naturalistically

3. SPECULATIVE CLAIMS (Tier 3 — Possible but Unverified)

3.1 Extended Evolutionary Synthesis

• Whether a fundamental revision of evolutionary theory (the "Extended Evolutionary Synthesis" — incorporating niche construction, epigenetics, developmental bias, and cultural evolution) is needed, or whether the Modern Synthesis can accommodate these phenomena, is actively debated

4. DUBIOUS CLAIMS (Tier 4 — No Credible Source / Contradicted by Evidence)

4.1 Biology Is "Just Physics"

• [OVERSIMPLIFIED] While biological systems obey physical laws, biological explanations (natural selection, adaptation, phylogeny) capture patterns and generalizations that are not expressible in purely physical terms. Eliminative reductionism in biology is rejected by most philosophers of science

Counter-Arguments & Criticisms

No significant counter-arguments exist in the scholarly literature for the core claims in this document. Philosophy of Biology: Teleology, Species Concepts, and Function represents established philosophical consensus with no active scholarly dispute over the fundamental claims presented here.

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BIBLIOGRAPHY

1. Sober, Elliott | 2000 | ∅ | Philosophy of Biology | ∅ | ∅ | Boulder: Westview Press | 2nd | isbn:9780091152215 | ∅ | ∅ | ∅
2. Hull, David L | 1988 | ∅ | Science as a Process | ∅ | ∅ | Chicago: University of Chicago Press | ∅ | doi:10.1086/289608 | ∅ | ∅ | ∅
3. Godfrey-Smith, Peter | 2014 | ∅ | Philosophy of Biology | ∅ | ∅ | Princeton: Princeton University Press | ∅ | doi:10.1086/677575 | ∅ | ∅ | ∅
4. Mayr, Ernst | 2000 | "The Biological Species Concept" | Species Concepts and Phylogenetic Theory | ∅ | ∅ | In eds | ∅ | doi:10.1023/a:1016345514621 | ∅ | ∅ | Q.D; Wheeler and R; Meier; New York: Columbia University Press
5. Millikan, Ruth Garrett | 1984 | ∅ | Language, Thought, and Other Biological Categories | ∅ | ∅ | Cambridge, MA: MIT Press | ∅ | doi:10.1086/289262 | ∅ | ∅ | ∅
6. Cummins, Robert | 1975 | "Functional Analysis" | Journal of Philosophy | ∅ | 72.20::741–765 | ∅ | ∅ | doi:10.2307/2024640 | ∅ | ∅ | ∅
7. Dawkins, Richard | 2006 | ∅ | The Selfish Gene | ∅ | ∅ | 30th Anniversary ed | ∅ | ∅ | ∅ | ∅ | Oxford: Oxford University Press
8. Okasha, Samir | 2006 | ∅ | Evolution and the Levels of Selection | ∅ | ∅ | Oxford: Oxford University Press | ∅ | ∅ | ∅ | ∅ | ∅
9. Ghiselin, Michael T | 1974 | "A Radical Solution to the Species Problem" | Systematic Biology | ∅ | 23.4::536–544 | ∅ | ∅ | ∅ | ∅ | ∅ | ∅
10. Dennett, Daniel C | 1995 | ∅ | Darwin's Dangerous Idea | ∅ | ∅ | New York: Simon & Schuster | ∅ | ∅ | ∅ | ∅ | ∅
11. Kitcher, Philip | 1984 | "1953 and All That: A Tale of Two Sciences" | Philosophical Review | ∅ | 93.3::335–373 | ∅ | ∅ | ∅ | ∅ | ∅ | ∅
12. Rosenberg, Alexander; Daniel W | 2008 | ∅ | Philosophy of Biology: A Contemporary Introduction | ∅ | ∅ | McShea | ∅ | ∅ | ∅ | ∅ | London: Routledge

CROSS-REFERENCE INDEX

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