a1 School of Life Sciences, Heriot Watt University, Edinburgh EH14 4AS, United Kingdom email@example.com http://www.sls.hw.ac.uk/staffDetails.php?staff_id=37
a2 Centre for Research in Human Development, Psychology Department, Fylde College, Lancaster University, Lancaster LA1 4YW, United Kingdom firstname.lastname@example.org http://www.psych.lancs.ac.uk/people/CharlieLewis.html
a3 Department of Experimental Psychology, University of Bristol, Bristol BS8 1TH, United Kingdom N.Freeman@bristol.ac.uk http://psychology.psy.bris.ac.uk/people/normanfreeman.htm
We see no grounds for insisting that, because the concept natural number is abstract, its foundations must be innate. It is possible to specify domain general learning processes that feed into more abstract concepts of numerical infinity. By neglecting the messiness of children's slow acquisition of arithmetical concepts, Rips et al. present an idealized, unnecessarily insular, view of number development.