Men engage in more reckless behavior

The argument

Men are socialized to engage in more risky behaviors over the course of their lifetimes, and the cumulative effect of that difference is one reason women live longer. The pattern shows up wherever risk is taken voluntarily. For example, 75% of the accidental deaths at the Grand Canyon — from falling or various other accidents — are men. More generally, men are more likely to engage in brawls, fights, dangerous driving, and a variety of other risky and dangerous behaviors. What these have in common is that the hazard is not distributed by chance but entered into, which is why the disparity is so large in categories of death that are avoidable by definition. Individually, each of these behaviours carries only a small probability of a fatal outcome. The mortality effect comes from repetition across a lifetime, and it is visible in the aggregate statistics: unintentional injuries are the third leading cause of death in men, so it's no surprise that, generally speaking, they tend to die sooner or at a younger age than women. Deaths of this kind also tend to occur early, which removes more years of life per death than the illnesses that dominate later mortality. Socialization may not be the whole explanation. This could be due to certain biological factors as well — some studies suggest that the parts of the brain responsible for risk calculation develop more slowly in males than in females, which would mean the same situation is appraised differently rather than the same appraisal being acted on differently. This could be the reason why your average man is more likely to engage in risky behavior that your average woman would not. On either account, the behavioural difference is real and its effect on life expectancy follows from it.

Premises

Counter-arguments

To argue that men have more slowly developed brains than women is absolutely sexist. Unintentional injury is the 6th leading cause for women in the United States, so to suggest that women do not engage in risky behavior as men do is clearly false.

Rejecting the premises

[Rejecting P1] The premise runs together a well-supported social observation and a much weaker biological one. Sex differences in risk-taking are documented, but the claim about slower-developing risk-calculation regions is contested and carries far more weight in the argument than the evidence supports — socialisation alone would produce the same pattern. [Rejecting P2] Unintentional injury is a leading cause of death for women too, and accidents account for a modest share of deaths overall. The life-expectancy gap is driven mainly by cardiovascular disease and cancer at older ages, not by accidents among the young. [Rejecting C] 'In part' is the defensible version, and it is all the premises support. Risk behaviour contributes alongside smoking and drinking rates, later help-seeking, occupational exposure, and biological factors that appear in other species as well — making behaviour one component of the answer rather than the answer.