R.R. Sokal & P.H.A. Sneath

1963: Principles of numerical taxonomy

'Artificial' classification

Character analysis

No subordination

Classification reflects similarity

'Similar' = similar

All characters equally good

Initially very rigorous methods

Distinct groups

Willi Hennig (1913-1976):

1950: Grundzüge einer Theorie der phylogenetischen Systematik.

1963: Phylogenetic Systematics.

'Natural' classification

Character analysis

No subordination

Classification reflects evolution

'Similar' = common origin

All characters not equally good

Initially very 'loose' methods

Distinct groups