Do the first five consciousnesses have a thinking function?

The first five consciousnesses also have the five universally operative mental factors: attention (manaskāra), contact (sparśa), feeling (vedanā), perception (saṃjñā), and volition (cetanā); they are simply simpler and coarser than the five universally operative mental factors of the sixth and seventh consciousnesses. The sixth and seventh consciousnesses deliberate on mental sense-objects (dharma-viṣaya), and their deliberation can be very refined and profound, whereas the first five consciousnesses deliberate on the five sense-objects (pañca-viṣaya), and their deliberation is very coarse and simple. As long as one can separate the five sense-objects from the mental sense-objects and avoid confusing them, one can distinguish the difference between the volition of the five consciousnesses and the volition of the sixth and seventh consciousnesses. The volition of the five consciousnesses is not the kind of deliberative function that the mind consciousness has; the two are different, and the difference is quite substantial. Separating the five sense-objects from the mental sense-objects is extremely difficult, so distinguishing the recognition of the five consciousnesses from that of the mind consciousness is also very difficult. Likewise, most people cannot distinguish the functions and roles of the manas from those of the mind consciousness.

What people ordinarily call deliberation generally refers to the deliberation of the sixth and seventh consciousnesses on mental sense-objects, especially the deliberation of the solitary consciousness (mano-vijñāna-eka-citta) on the subjectively imagined realm; the five consciousnesses cannot but participate in it. The volition among the five universally operative mental factors of the five consciousnesses mainly serves the function of judgment and decision. After the five consciousnesses recognize their corresponding five sense-objects, they take the marks of those five sense-objects, make a simple and coarse judgment, and then decide whether to continue recognizing or to stop and avoid; the mind consciousness simultaneously participates in the recognition. The reason the recognition of the five consciousnesses is said to be coarse is that the five sense-objects are coarse and do not require detailed discrimination; therefore the recognition is fast and does not require much mental effort from the five consciousnesses, as if it did not go through the brain at all. The mental sense-objects that accompany the five sense-objects, however, are relatively subtle and require the refined recognition of the mind consciousness, so the mind consciousness's recognition and analytical thinking are both slower and more mentally taxing.

When the five sense-objects are significant and their impact is great, the manas makes its decisions primarily according to the judgment and decision of the five consciousnesses, with no time to process the mind consciousness's analysis and judgment, and thus overlooks the mind consciousness's recognition and deliberation. Usually the recognition of the five consciousnesses is rather direct and fast, while the recognition of the mind consciousness is subtle and slightly slower than that of the five consciousnesses; for major matters, the manas relies mainly on the reactions of the five consciousnesses and cannot attend to the reactions of the mind consciousness. Therefore, in some sudden emergencies, there is no time for the mind consciousness's analysis and deliberation—the manas directs the completion of the matter, causing the mind consciousness to be slow to realize it afterward. To summarize: deliberation refers to the deliberation of the sixth and seventh consciousnesses; the volition of the first five consciousnesses is simpler, coarser, and more direct than deliberation, not deep enough—and it does not need to be deep, because the five sense-objects are shallow, coarse, and direct in their dharmas.