Seems like the consensus is that there is no consensus, only many people with strong opinions either way.
Perhaps the question is underspecified, and we need to ask more precisely: what kind of porn? for whom? how often? compared to what alternative? harmful for whom? (etc., see DirectedEvolution’s answer).
Now of course this sounds like a fully general counterargument—we can deflect any inconvenient question by asking endlessly (are apples healthy? -- what kind of apples? for whom? how many? compared to what?), but with apples, we can assume some reasonable defaults, like “the kind of apples you can buy in a supermarket, or grow in your garden” and “somewhere between one apple a week and ten apples a day”, and within this range the answers will probably be quite similar.
With porn, the range is probably much wider. Frequency, from “a magazine hidden under my bed, which I browse once in a month”, to “I am an unemployed guy and I spend 16 hours a day watching porn online”. The kind of porn, from mere uncovered boobs, or the kind of vanilla sex that your Pope would approve of, to the most depraved shit that would leave an average person traumatized for the rest of their lives. Is watching porn a part of a balanced lifestyle that also includes seeing real people occasionally; or a way to overcome solitude during your climb to the top of Mt. Everest; or a neurotic distraction while you procrastinate on filing your tax reports?
Arguments in favor of porn:
some people like it;
under some hypothetical, extremely rare circumstances that practically never happen in real life, carefully selected porn could serve as a form of sex education;
for perverts who are turned on by horrible things, watching porn is a socially preferable alternative to actually doing horrible things in real life;
no one gets pregnant from watching porn;
people can find inspiration that will enrich their sexual lives;
watching porn together with your partner can be a form of foreplay.
Arguments against porn:
it makes Jesus cry;
it makes you objectify people, and that’s wrong;
general objection against superstimuli (you can see more attractive people naked during one evening than your ancestors could see naked or clothed during their entire lifetime, isn’t that amazing?);
if you spend too much time—you should be doing something useful instead;
seeing too many too attractive people may set one’s bar unrealistically high;
and vice versa, people can be afraid that porn sets other people’s bars too high;
seeing too much too soon can make people scared of actually trying sex (afraid that their partners would expect things they are not comfortable with);
people may not realize that average porn is not representative of average sex (things that look best on screen are not necessarily the things that feel best in real life; perverts are better customers than normies, therefore their preferences are overrepresented);
people saturated with porn may be less motivated to find partners in real life, or may neglect their existing partners;
multiply the changes in individual behavior by millions, and you get social changes (fewer marriages? fewer kids?);
sometimes porn is produced unethically (people coerced into performing);
masturbating while watching porn makes you lose precious bodily fluids.
One strong argument in favor of porn is that almost nobody alive gets as much sex as they actually want; vast majority gets less than they want, minority gets too much, and without some kind of extreme social engineering this cannot be solved.
Porn is the closest thing to a “bandaid solution” to that problem. Sexless or severely undersexed people can achieve an illusion of sex life with porn. Yes, porn is addictive and can an be psychologically harmful, but involuntary celibacy is definitely severely harmful, and we cannot solve it any other way.
Seems like the consensus is that there is no consensus, only many people with strong opinions either way.
Perhaps the question is underspecified, and we need to ask more precisely: what kind of porn? for whom? how often? compared to what alternative? harmful for whom? (etc., see DirectedEvolution’s answer).
Now of course this sounds like a fully general counterargument—we can deflect any inconvenient question by asking endlessly (are apples healthy? -- what kind of apples? for whom? how many? compared to what?), but with apples, we can assume some reasonable defaults, like “the kind of apples you can buy in a supermarket, or grow in your garden” and “somewhere between one apple a week and ten apples a day”, and within this range the answers will probably be quite similar.
With porn, the range is probably much wider. Frequency, from “a magazine hidden under my bed, which I browse once in a month”, to “I am an unemployed guy and I spend 16 hours a day watching porn online”. The kind of porn, from mere uncovered boobs, or the kind of vanilla sex that your Pope would approve of, to the most depraved shit that would leave an average person traumatized for the rest of their lives. Is watching porn a part of a balanced lifestyle that also includes seeing real people occasionally; or a way to overcome solitude during your climb to the top of Mt. Everest; or a neurotic distraction while you procrastinate on filing your tax reports?
Arguments in favor of porn:
some people like it;
under some hypothetical, extremely rare circumstances that practically never happen in real life, carefully selected porn could serve as a form of sex education;
for perverts who are turned on by horrible things, watching porn is a socially preferable alternative to actually doing horrible things in real life;
no one gets pregnant from watching porn;
people can find inspiration that will enrich their sexual lives;
watching porn together with your partner can be a form of foreplay.
Arguments against porn:
it makes Jesus cry;
it makes you objectify people, and that’s wrong;
general objection against superstimuli (you can see more attractive people naked during one evening than your ancestors could see naked or clothed during their entire lifetime, isn’t that amazing?);
if you spend too much time—you should be doing something useful instead;
seeing too many too attractive people may set one’s bar unrealistically high;
and vice versa, people can be afraid that porn sets other people’s bars too high;
seeing too much too soon can make people scared of actually trying sex (afraid that their partners would expect things they are not comfortable with);
people may not realize that average porn is not representative of average sex (things that look best on screen are not necessarily the things that feel best in real life; perverts are better customers than normies, therefore their preferences are overrepresented);
people saturated with porn may be less motivated to find partners in real life, or may neglect their existing partners;
multiply the changes in individual behavior by millions, and you get social changes (fewer marriages? fewer kids?);
sometimes porn is produced unethically (people coerced into performing);
masturbating while watching porn makes you lose precious bodily fluids.
Now good luck putting this all into one equation!
One strong argument in favor of porn is that almost nobody alive gets as much sex as they actually want; vast majority gets less than they want, minority gets too much, and without some kind of extreme social engineering this cannot be solved.
Porn is the closest thing to a “bandaid solution” to that problem. Sexless or severely undersexed people can achieve an illusion of sex life with porn. Yes, porn is addictive and can an be psychologically harmful, but involuntary celibacy is definitely severely harmful, and we cannot solve it any other way.
“Mandrake, have you never wondered why I drink only distilled water, or rainwater, and only pure-grain alcohol?”