What these cases bear on is the idea that there is lawful specification of affordance by an optical property.
Thus we have two laws relating properties: 'o-ness -> c-ness' (between occurrent property and affordance) and 'e-ness -> o-ness' (between optical property and occurrent environmental property). By transitivity we have: 'e-ness -> c-ness'. That is, there is a lawful specification of an affordance by an optical property. In sum, there is a legitimate construal of dispositions and of natural law that, in principle, allows affordances to be optically specified, thus denying (on grounds separate from those identified in Section 4) Fodor and Pylyshyn their argument against the direct perception of ecologically-significant properties. Recall that Fodor and Pylyshyn admit quite cheerfully in the conclusion of their Section 4 that if there were laws about ecological kinds then there could be direct detection of ecological kinds. (TSRM, 1981, p. 266).So, I'm pursuing (in my blogolife), though I do not yet claim to have, an objection that goes pretty close to the heart of the TSRM paper. I'm challenging the idea that there is a lawful specification of affordances by optical properties. The argument might not work, but I'm not just firing random shots in the air.