In this following wikipedia link I read, it gives examples of an appeal to consequences, as either positive or negative form, where the consequent is desirable or undesirable, and then notes that the modus tollens is a different inference because the negation of the consequent of a modus ponen is a negation rather than an undesirable thing P, and can determine the truth value of the premise
EXAMPLE:
If it is human then it is a vertebrate.
It is not a vertebrate therefore is not human. (correct modus tollens application)
However, wiki then goes on to mistakenly give examples of a modus ponen rather than an appeal to consequences by arguing that the following argument is an appeal to consequences;
"Evolution must be false: if it were true then human beings would be no better than animals, since we would be descended from them."
But in fact this has little to do with desirability, which has to make me wonder why they chose two examples, one being something to do with freewill, which is essentially theistic, and an argument against evolution which is essentially theistic.
In both examples, the examples given are actually better examples of modus ponens, where the tollens can be used, rather than desirable things for certain facts about the world aren't merely desired outcomes but are realities, so the examples they give may be correct because if evolution was true certain circumstances may be reasonably expected, such as humans basically being no better than animals or to expect more than one type of animal like a human, out of all of the millions. This is at the least, a reasonable possibility rather than any desirable outcome..and who has the patent on what to expect if evolution is true without indulging in hindsight such as; "well, here we all are, therefore the facts presented are what we would expect from evolution". (circular reasoning)
A better way to present that example would be as a modus ponen;
If evolution were true then man would not be expected to be special or stand out, or have creative/designer abilities that might match with him being made in God's image as a persona, as there would be no reason to expect a spiritual, creative being that excels so much as to create it's own artificial world on the world.
These things clearly are true, and humans are examples of those things in their unique and peculiar abilities, therefore evolution is false.
(while I am not saying that is the strongest modus ponen ever, and I am not arguing it here as such, my point is it isn't an appeal to consequences, it is the expectation of certain facts if a proposal is true. )
Before you are outraged, Dr Sarfati PHD also says that it may be reasonable to refute the auxiliary hypothesis rather than the hypothesis itself.
So a better form of that argument may be this;
If evolution then auxiliary hypothesis P, and if P then X evidence.
Not X therefore not aux P, (but not necessarily a negation of evolution theory, because it is debatable as to whether we can propose P on behalf of evolution.)
That seems fair in the sense that if a consequent is debatable, then you can't necessarily negate the antecedent.
For example;
"If Bob was a millionaire he would have two cars."
"He doesn't have two cars therefore is not a millionaire".
As you can see, this may or may not follow so isn't the best modus ponen. But it seems at least possible to propose it as a possibility.
If, and only if certainly P follows from X, then X can be negated.
I can't know whether evolution could create humans if evolution did occur, so technically I would say it might be fair to offer a pawn in the place of evolution theory, thus;
If evolution theory (X) is true, then according to my auxiliary proposal (P) I propose that Z would follow.
Z does not follow therefore, not P but not necessarily, 'not X'
(I am being conciliatory because I am not actually trying to attack evolution theory, I am trying to show that wikipedia doesn't seem to have a full grasp of what it is talking about it seems to me.
It is basically more reasonable to expect mankind to be special if man is made in God's image, and not to be if mankind isn't.
Conclusion: I am not sure wiki's examples are very good, because if a consequent clearly does follow an antecedent then this is not the same as a desirable consequence because it does not matter if a desirable consequence follows an antecedent but it does matter that certain facts follow an antecedent, in determining the truth-value of that proposal.
It seems to me wiki notes this, but then contradicts itself by giving an example of a modus tollens rather than an appeal to consequences.
Appeal to consequences - Wikipedia
At this other site below, again the examples seem to refer to theism in some way. They do seem to describe the appeal to consequences correctly here;
Logical Forms:
X is true because if people did not accept X as being true then there would be negative consequences.
X is false because if people did not accept X as being false, then there would be negative consequences.
X is true because accepting that X is true has positive consequences.
X is false because accepting that X is false has positive consequences.
Appeal to Consequences
A good and correct example I can think of, which isn't an attack of theism (for once) might be this;
Abortion being morally right is true, because if people did not accept this as true then there would be negative consequences, nobody to adopt babies, or care for them, etc....therefore abortion being morally correct, is true. (A genuine appeal to consequences).
I have a suspicion that atheists write a lot of the content on these sites, which you may think is cynical of me, but the thing is I would say that 90% of all examples seem to be strawman fallacies of some form that theists don't really seem to argue, or at least it would be hard to find many theists arguing those examples in the specifically devious and misrepresentative way that wiki seems to present it in.
Whether or not you agree or disagree they are wrong, it seems to me that wikipidia only presents theistic arguments as examples. You can provide neutral examples from wiki which is fine, but are there any examples where wiki will attack an argument that may stem from a more atheistic ideology?
Of course obtuse people may respond; "the examples are only theistic because only theistic arguments are fallacious", but obviously I can't take that very seriously. The fact is atheists argue fallacies a LOT, I come across it each day, but it seems like propaganda, that the likes of wiki seem to want to portray only the non-religious as rational people by making their examples some type of theistic argument, be it explicitly or more implicitly.
(of course you may say, "it's undesirable for man to not be better than animals or be machine-like" but it seems like a stretch to me, a stretch to contrive a theistic argument to attack, as propaganda.
Edited by mike the wiz, : No reason given.