So umm yeah, as description says, debaters must use deductive reasoning to justify their standard. thus, no subjective morality is allowed to begin with.

So reasoning must be in form of:

A = B

B = C

C = A

With of course starting premise also being logically deduced.

Due to is-ought gap, using observations to derive "should" is not possible, because observations merely tell what is, not what should be.

However, using logical axiom as starting premise works as foundation to derive morality from, and the only way to deny logical axiom is to deny logic itself.

thus, my reasoning will be in form of:

A or not A

Not A, when accepted as true, results in self-defeat and establishment of A.

thus, only A remains as true.

I. Body autonomy objective morality

When it comes to what "should" be done, some moral principles survive A or not A much better.

Some examples of moral principles are:

Body autonomy

Property rights

Person's wants

Harm

Freedom

We can logically deduce body autonomy by saying:

Everyone has body autonomy = No one can take away body autonomy of another

this principle remains self-consistent, but opposite principle does not:

Any person can take away body autonomy from others for subjective reasons = Everyone can take body autonomy from everyone for any subjective reason, including their ability to take away autonomy from others = Ability to take away autonomy itself disappears as principle.

Suppose someone says:

"I have right to take away body autonomy of others for reasons I choose".

We can respond to that by saying:

"We have right to take away your ability to take away body autonomy of others for reasons we choose".

thus any attempt to take away autonomy results in symmetry justification to prevent that same attempt.

Any person has right to take away choices from others = Any person has right to take away choice to take away choices from others.

thus, any attempt to take away body autonomy for subjective reasons, results in also subjective reasons defeating same principle.

Because topic is about smoking and age restrictions, body autonomy is important argument.

Suppose some person wants to smoke and has money to buy cigarettes. to impose age restrictions which prevent that person, then his wants, choices, autonomy and property choices would all be violated.

And if violating body autonomy is good for subjective reasons, it results in justification to violate all autonomy, including ability to violate autonomy, hence self defeat of "Not A".

Likewise, violating property choices is self-defeating:

Any person can take away property choices from another for arbitrary reason = All choices regarding property can be taken away, including choice to take away choice.

Any person can deny goals of another = Any person can deny goals of all others, including goals to deny goals.

Freedom likewise works same. If freedom can be taken away for subjective reasons, all freedom can be taken away for subjective reasons, including freedom to take away freedom.

II. Future wants argument

One of biggest counters to body autonomy of children is that violating it maybe upholds their future autonomy.

However, such counter doesnt work, because justification for it rests on same subjective reason as any other violation of autonomy.

We can logically deduce that "no one can violate body autonomy of others".

We cannot logically deduce "We can violate autonomy of others if it possibly upholds their future autonomy".

Because when:

Autonomy can be violated = Who gets to decide when it gets violated and for what reason?

And that question is a core self-defeat of all principles which attempt to violate body autonomy.

Any person can decide when autonomy gets violated = Any person can decide to violate autonomy of anyone always

And violating autonomy to preserve autonomy is a self defeating principle, because autonomy remains non-violated only if never violated. If it is violated, it is no longer autonomy but a removed autonomy.

It is not possible logically to follow a principle "No one gets to violate autonomy of others" while violating autonomy of others, for whatever reason the violation occurs.

And as autonomy principle is deduced from deductive logic, "future autonomy > current autonomy" argument is not only unproved and not logically deduced, but is self-defeating because it attempts to use subjective justification to violate autonomy, while same can be used to defeat it.

Principle is justified by subjective reason = Principle can be defeated by subjective reason

III. Harm argument

Another big counter to child's autonomy is harm argument, usually in its more objective form:

Any person can cause harm to others and justify it for subjective reasons = All harm becomes justified = Harm to prevent harm becomes justified.

However, the flaw of harm argument is essentially misunderstanding what harm is.

Harm entirely depends on desirable state of things or desirable functions being violated.

However, when it comes to wants and desires, cigarettes can be desirable on balance, so to not allow smoking would itself be harm.

Any person can deny wants of others for subjective reasons = all wants can be denied for subjective reasons, including wants of person to deny wants of others, hence resulting in inability of any person to deny wants (opposite principle)

Wants can be denied for subjective reasons = Wants to deny wants of others can likewise be denied for subjective reasons.

thus, "no person can deny wants of others", remains as true objective principle, because opposite principle simply doesnt survive dichotomy.

Harm argument likewise can be negated by body autonomy.

Body autonomy = Objective principle

In dichotomy between harm and body autonomy: Objective principle of body autonomy prevails.

Because harm can be justified by using not arbitrary, but objective principle of body autonomy.

Harm justified for objective reasons =/= Harm justified for subjective reasons.

So if body autonomy results in what person considers to be "harm", that harm is still not objectively wrong, because it isnt done with subjective justification, but an objective justification of body autonomy.

IV. Power/authority argument

One of big counters to moral principles and body autonomy is "might makes right".

In other words, someone can say:

"My decision to deny autonomy of others is justified by my power to do so."

However, power principle doesnt work in "should" debates, because it doesnt say what should or shouldnt be done.

Society has power to both impose and remove age restrictions, and having power alone doesnt deduce logically which decision should be made.

Likewise, morality which uses power as justification justifies anything, even my position. If something is justified by power, then all thoughts and actions which exist are justified by some power which enables them to exist, including my own position.

V. Subjective morality justification

Any moral principle derived from arbitrary reasons cannot be justified, and any excuse for violating objective principle by using arbitrary reasons merely enables its own denial by other arbitrary reasons.

Arbitrary reasons can be used to deny principle = Other arbitrary reasons can be used to deny those arbitrary reasons, and justification of "arbitrary reasons can be used to justify or deny" becomes self-defeat.

VI. Symmetry reciprocity principle

Any attempt to justify denying autonomy of others rests on these conditions:

1. Justification for denial
2. Ability of denial

Because justification is always arbitrary, same can be denied arbitrarily too, and 2 can be denied arbitrarily as well.

the only justification which would work is objective justification.

But who decides what objective justification is?

If anyone can decide what objective justification is = Anyone can decide to deny others of body autonomy based on what they think is objective justification, including denying ability to deny body autonomy, hence self defeat of any attempt at justification to deny body autonomy, even with what person thinks are "objective reasons.

VII. Opponent's burden

Because my opponent is ultimately arguing to violate body autonomy, the conditions for his position to be true are:

1. Objective justification derived through deductive reasoning with starting premise being logical axiom
2. Who decides what objective justification is?
3. Who decides who gets to decide?
4. Can objective justification be denied by some other objective justification?
5. Solution to "ability of anyone to decide objective justification resulting in self-defeat".
6. Who has ability to decide, and who gives that ability?

Compare that to simple body autonomy.

Everyone has body autonomy = No one violates autonomy of another

Principle is self-consistent, not self-defeating. the opposite principle, when accepted, defeats itself and returns to original principle after futile struggle to come up with justification which ends up being justification against the very principle using it, because symmetry argument which relies on same abilities defeats it.

If person says: "I can decide what objective justification for violating autonomy is",

I can say " then so can I, and I reject yours".

Conclusion:

With objective principle of "thou shall not violate autonomy of others" being logically deduced, and opposite principles resulting in self-defeat,

what follows is:

Choosing to smoke = allowed by body autonomy

Allowed by body autonomy = Allowed by objective morality

Choosing to smoke = Allowed by objective morality

Age restrictions = not allowed because they violate body autonomy

Violate body autonomy = Violate objective moral principle

Age restrictions = Violate objective moral principle.

So a person who smokes in private and doesnt smoke with others who are unwilling to inhale smoke, isnt violating autonomy of others.

But placing age restrictions is a violation of body autonomy and property choice.