Two views on object or cause of contracts

X sold to Y a desktop computer for Php50,000. In this contract of sale, which is the object, and which is the cause?

There are two views on this. The first view is that the object or the cause depends on whether the viewpoint considered is that of the seller or the buyer. Insofar as the seller is concerned, the object is the desktop computer while the cause is the Php50,000 payment (or the giving of the money). On the other hand, regarding the buyer, the object is the Php50,000 payment (or the giving thereof) while the cause is the desktop computer (because he parted with his money for the computer).

The second view, which has been tagged as better by experts in civil law such as Paras, insofar as both the seller and the buyer are concerned, there is only one subject matter -- the desktop computer. The cause or consideration for the seller is the Php50,000 payment (or the giving thereof). Whereas, for the buyer, it is the delivery to him of the desktop computer.