Abstract
The current review and synthesis was designed to provocatively develop and evaluate the proposition that
“fear of the unknown may be a, or possibly the, fundamental fear” (Carleton, 2016) underlying anxiety and
therein neuroticism. Identifying fundamental transdiagnostic elements is a priority for clinical theory and
practice. Historical criteria for identifying fundamental components of anxiety are described and revised
criteria are offered. The revised criteria are based on logical rhetorical arguments using a constituent
reductionist postpositivist approach supported by the available empirical data. The revised criteria are
then used to assess several fears posited as fundamental, including fear of the unknown. The review and
synthesis concludes with brief recommendations for future theoretical discourse as well as clinical and
non-clinical research.