There are two key assumptions here: (i) sex automatically implies an especially deep bond, deeper than even the deepest platonic friendship and (ii) it is nearly always suboptimal to have more than one such deep bond. Assumption (i) is extremely dubious given that one-night stands are fairly common. Assumption (ii) is harder to disprove, but personally I am skeptical about it. Yes, there can be increasing returns from investing in a relationship with one person, but there can also be diminishing returns (for example because different relationships have complementary benefits). So, while this type of argument carries some weight, I doubt it can justify monogamy on purely pragmatic grounds.
Assumption (i) is extremely dubious given that one-night stands are fairly common.
I think it is possible that humans are bimodal about this. For some, sex is a strongly emotional, for others not at all. (Or maybe even for the same person it depends on circumstances.)
And the conservative rules about chastity are partially about pregnancy and diseases, but also partially to prevent people who create deep bonds from choosing partners who cannot reciprocate.
There are two key assumptions here: (i) sex automatically implies an especially deep bond, deeper than even the deepest platonic friendship and (ii) it is nearly always suboptimal to have more than one such deep bond. Assumption (i) is extremely dubious given that one-night stands are fairly common. Assumption (ii) is harder to disprove, but personally I am skeptical about it. Yes, there can be increasing returns from investing in a relationship with one person, but there can also be diminishing returns (for example because different relationships have complementary benefits). So, while this type of argument carries some weight, I doubt it can justify monogamy on purely pragmatic grounds.
I think it is possible that humans are bimodal about this. For some, sex is a strongly emotional, for others not at all. (Or maybe even for the same person it depends on circumstances.)
And the conservative rules about chastity are partially about pregnancy and diseases, but also partially to prevent people who create deep bonds from choosing partners who cannot reciprocate.