The Continuity Criterion, by Entity Class:

Continuity:  "Continuity" will stand for "physical continuity."  This is the continuance of physical structures in a body over time.  Individual atoms may be replaced, but the replacement atoms must be of the same elements as the atoms lost, so that the structures retain their functional characteristics over time.

Inanimates:  Some inanimates lack long-term structure.  Sparks, clouds, aurorae — all transient phenomena fall into this category.  Other inanimates, such as crystals, passively retain their structure over time.  And some inanimates actively maintain, and even replicate, their structure.  As examples, we can note the autocatalytic, or "self-copying" chemistry of certain pre-biotic systems.  Amino-adenosine and a complex aromatic ester form a product which autocatalyzes in chloroform.  And micelles (charged polymers) of lithium hydroxide and octanoic acid sodium salt autocatalyze within an organic solvent.[1]

       Do inanimates satisfy the continuity criterion?  We can say that some do.

Eukaryotes/prokaryotes:  These single-celled organisms maintain the integrity of their living structures over time.  Some receive energy and nutrients passively.  Others actively obtain their sustenance through simple chemistry-mediated searches.  But regardless of the means, the end is the same:  all single-celled creatures satisfy the continuity criterion.

Multi-celled plants:  What is true of single-celled plants is true of multi-celled plants as well.  All multi-celled plants satisfy the continuity criterion.

Computers:  Computers are an odd case.  It may be interesting to see how they compare with the other classes of entities when judged by the same criteria.

       Computers passively retain their structure over time because they are composed of inert materials.  Those computers equipped with robotic appendages can replace parts which have failed, and thereby actively maintain themselves.  Additionally, John von Neumann[2] has provided a proof that computers can, in theory, maintain and replicate themselves without error, indefinitely.

       So by passive or active means all computers satisfy the continuity criterion.

Invertebrates:  What is true of single-celled animals is true of multi-celled animals as well.  All invertebrates satisfy the continuity criterion.

Vertebrates:  Again, what is true of single-celled animals is true of multi-celled animals as well.  All vertebrates satisfy the continuity criterion.

Mammals:  As with vertebrates generally.  All mammals satisfy the continuity criterion.

Great apes:  As with mammals generally.  All great apes satisfy the continuity criterion.

Humans:  All humans satisfy the continuity criterion.

Table 17.2 summarizes the results for the continuity criterion:

Table 17.2
Personal identity criteria, ordered by entity class

	Continuity	Memory	Subjectivity
Humans	all
Great apes	all
Mammals	all
Vertebrates	all
Invertebrates	all
Computers	all
Multi-celled plants	all
Eukaryotes/prokaryotes	all
Inanimates	some