 There is a major debate within the philosophy of mind between proponents of classical cognitive architecture and proponents of  connectionism  (see entry). The debate is typically presented as a debate about compositionality, but it is not exactly about that. The issue tends to be whether there are such things as meaningful constituents of thought (perhaps in the extended sense in which traffic signs can be said to have meaningful constituents), and if there are, whether these contribute the same thing (presumably their meaning) to all thoughts in which they occur. If the answer to the first question is negative, the question of compositionality does not arise. If the answer to the first question is positive, the second is independent of compositionality. (It could be that thought-constituents contribute always the same thing to a thought of which they are constituents, but these contributions, even together with the way the constituents are combined, severely underdetermine the meaning of the thought. And it could be that thought-constituents contribute different things to different thoughts—depending, perhaps, on the surroundings of the thinking—but these variable contributions, plus the way the constituents are combined, fully determine the meaning of the thought.) The debate about connectionism is more closely related to the question whether reverse compositionality holds (cf.  section 1.6.4.) 