Meeting 2:3 – Life and Artificial Life


Pennock, Robert T (2012) Negotiating boundaries in the definition of life: Wittgensteinian and Darwinian insights on resolving conceptual border conflicts. Synthese 185:5–20.


Summary: Lucas Mix presented a summary of the article.

Christopher Langton coined “ALife” as “The study of man-made systems that exhibit behaviors characteristic of natural living systems”

Cluster Definitions (a la Wittgenstein) includes stated examples and similar cases (begging the question of what kind of similarity). Cluster definitions include some idea of family resemblance. [Compare type species]

What is the contrast class for life?

“That is, in analyzing concepts and constructing definitions here, we are playing a word game, but not just a word game, for science aims for its terms to refer to empirical reality and not be mere conventions.” 9

Conway’s Game of Life as proto-ALife, developing complexity from simple rules. “Artificial life researchers typically take a “bottom-up” view, holding that the complex, high-level global patterns of life arise from simple, low-level, local interactions.” 9

Is Conway’s Game of Life an example of life? It appears to have motion and emergent complexity, but there is no metabolism or adaptation.

Consider the non-parity between “alive” and “dead.”

[Pennock compares “animate” and capable of moving, presenting an etymology that animate comes from animals. This is slightly misleading. Latin anima, and Sanskrit aniti refer to having breath or a soul.]

Avida as in silica evolution: mutating, replicating programs competing for CPU time.

Is Avida an example of living things? They have teleological behavior as life does (p16).

What it the point of having a sign (word) for life?

“ALife systems get the causal connections right… InAvida, the organisms contain their own sequences of instructions which control self-replication. For all the essential Darwinian mechanisms, the causal processes are hooked up in the right way.” 14 [What does he mean by this?]

Does the fact that artificial life involves artifice mean that it is not real life?

How does a “Darwinian” definition of life relate to a “Darwinian” origin of life?

Causal mechanisms [in the external world?] impact our survival, therefore there must be better and worse definitions to this end. 18

“We cannot just make of the world what we will, but must meet it half way” [Why not all the way?]

Darwinian evolvers is a pragmatic definition of life, but perhaps not the definition of life. There need not be only one.



Pennock, citing Lovelock, suggests that our recognition of living things is automatic. Perhaps it is an evolved heuristic. If so, how does this relate to our “rational” definition of life?

Can we diagram life? Some territory is clearly inside the circle (e.g., humans); some is clearly outside (molecular hydrogen). Is such an exercise informative?

How does moral value map onto life? Pennock believes it to be trivially true that we have no moral obligations to bacteria.


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