  Principles of cognitive economy would require that concepts about objects,
properties and relations should be introduced only if they simplify the
conceptualisation of a domain. Unexpectedly, classic logic conditionals,
specifying structures holding within elements of a formal conceptualisation, do
not always satisfy this crucial principle. The paper argues that this
requirement is captured by supervenience, hereby further identified as a
property necessary for compression. The resulting theory suggests an
alternative explanation of the empirical experiences observable in Wason's
selection tasks, associating human performance with conditionals on the ability
of dealing with compression, rather than with logic necessity.
