Logical fallacies: How not to think

Transcription

1 Introduction Logical fallacies: How not to think Distinguish valid / invalid arguments from correct / incorrect conclusions Specific fallacies often fall into several categories of fallacy Please do not attempt to infer anything from the following examples about what I personally think about the issues addressed. For the purposes of this exercise, my personal views are irrelevant, for the following examples are intended merely to illustrate logical fallacies, not to serve as arguments for or against any substantive positions. However, they are designed to make you think. In particular, you may discover that you currently hold certain views on the basis of logically fallacious arguments. This does not necessarily mean that these views are wrong (see The fallacy fallacy, no. 30), although naturally this is possible. At the very least, you will need to think again about why you believe what you do. And that won t do you any harm, will it? Logical fallacies 1. Lack of argument. Dismissing a conclusion with no argument whatsoever. Probably the most common logical fallacy: just listen to Radio 4 s Today programme for countless examples. Normally it s done by simply failing (or refusing) to address objections or questions raised against one s own position, allowing them to be lost in the cut and thrust of conversation. Question: might such an approach ever be appropriate? 2. Ad hominem (lit. to the man ). Arguing for or against a conclusion on the basis of the identity, character or circumstances of the person who espouses it. John is a great bloke, so maybe Baptist /Arminian / Roman Catholic / etc. theology isn t so bad after all. Steve s a complete hypocrite don t listen to him when he preaches about godliness! Be careful about what Dave says I could tell you a few things about him... I m tired of arguing with him he always thinks he s right. Question: are there any contexts in which it might be legitimate to appeal to the identity or character of the person making an argument? 3. Fallacy of accident. Arguing from an inadequately-defined general rule to a particular case. Men are capable of seeing, therefore blind men are capable of seeing. The congregation needs to hear how the Bible applies to their daily lives, so a sermon on the Trinity is irrelevant to them. It s good to be in full-time Christian ministry, therefore you should be in full-time Christian ministry. Evangelism is really important, so you should be doing evangelism. 1

2 4. Converse fallacy of accident. Arguing from a particular case to a general rule. A bang on the head helped him, therefore... Little Johnny was baptised and brought up by Christian parents, but he fell away, therefore baptism and Christian parenting don t influence whether a child grows up as a Christian. Some Sabbatarians are legalists, so Sabbatarianism is legalism. Paul wore sandals, so we should do the same. Paul s ambition was to preach the gospel where Christ was not known (Rom 15:20), so we should do the same. Paul expected to suffer during his ministry, so we should expect the same. Paul s priority was evangelism, and ours should be too. Question: is it ever legitimate to argue from a particular case to a general rule? 5. Ad misericordiam (lit. to pity ). Drawing attention to the plight of a person holding a position in order to invoke the sympathy of the audience and induce them to support that position. She had a terrible childhood, therefore she didn t do it. I know he s a practicing homosexual, but he was treating appallingly by his former church, so there s no way we should exclude him from the Lord s Table. Now would not be a good time to preach against Christians marrying non-christians Jane is due to marry Bob next Saturday, and he s not a Christian. Robert C. Tannehill, The Narrative Unity of Luke-Acts: A Literary Interpretation, Vol. 2 (Minneapolis: Fortress Press, 1994), p. 3, paragraph 2. Question: what impact should such circumstances have upon the way we treat people? 6. Appeal to authority. Claiming that a view must be true because of the (perceived) authority or status of the person holding it. Steve is the Minister, so he must be right. Many respectable scholars have serious problems believing in a literal hell. Question: is there such a thing as a legitimate appeal to authority? 7. Slippery slope fallacy. Arguing against a position simply by alleging that it will lead to a chain of other undesirable views. If you deny that creation took place in 6 24-hour days, you ll end up a liberal. If you believe in 6-day creation, you ll end up a fundamentalist. If you start holding your hands up when you sing, you ll end up believing that all believers must speak in tongues. Question: Is there any truth behind the idea of a slippery slope? Why? 2

3 8. Appeal to force / negative consequences. Arguing against a position by alleging (truthfully or untruthfully) that further unpleasant consequences will follow from accepting it. Vote for me, or I ll break your legs. Don t preach about hell you ll only irritate people. 9. Ad populum (lit. to the people?). Basing an argument upon an appeal to (legitimate or illegitimate) attitudes and prejudices held by the hearers. We all know how ungodly the Bishop is; so obviously he s wrong about justification by faith. 10. Non sequitur (lit. it does not follow?). The conclusion does not follow from the premises. Nicole s a great cook, therefore you should go to Sweden on holiday. Spurgeon was great preacher, so Baptist theology must be right. Human beings are responsible for their actions, therefore God is not sovereign. The Bible says we should care for the poor, therefore Christians should vote for a political party that advocates free education, free healthcare and third-world debt relief. 11. Appeal to emotion. The attempt to discredit or support a view on the sole basis of emotional language or arguments. God is creative, sacrificial and empowering, not coercive, and his glory consists in sharing life with, not dominating, others. God [...] makes his presence felt actively, responsively, relationally, dynamically, and reciprocally. [...] Conventional theology did not leave enough room for relationality in God s essence [...] Thus it is hard for conventional theism to deal with a relational and personal God, with a God really involved in the world, in short, with the God of the Bible. (Clark H. Pinnock, Most Moved Mover [Carlisle: Paternoster, 2001], p. 6). 12. Fallacy of complex or many questions. Presupposing answers to questions not asked. Have you stopped beating your husband yet? Have you always been a liar or are you just starting now? When are you going to stop talking such rubbish? Question: What answers are presupposed here, to what questions? 13. False dilemma (false dichotomy). Framing a question or statement so as to exclude implicitly one or more legitimate positions. Are you a pacifist or a warmonger? Do you believe in expository preaching or are you a Liberal? The Psalms teach us about Jesus, Israel s Promised Messiah; they weren t written to teach Christians how to pray. 3

4 14. Fallacy of multiple causation. The failure to realise that other (unacknowledged) factors may have caused the phenomenon observed. It s not my fault that the church was burgled after all, I shut the windows. Everyone I read the Bible with falls away, therefore... I smack my children whenever they do anything wrong, but they ve grown up to be unbelievers, so smacking is not helpful in Christian parenting. 15. Fallacy of composition. Affirming a proposition about the whole of an entity on the basis of a property of the parts, or vice versa (the latter is sometimes called the fallacy of division). Parts to whole: Each sentence of the book is well-constructed, therefore the book is well-constructed. Rowan is a heretic, and Rowan is an Anglican, therefore all Anglicans are heretics. Whole to parts: The book is red, therefore all of its pages are red. The Roman Catholic Church is apostate, therefore Clare (a Roman Catholic) is apostate. It s a prayerful church and she s a member, so she s a prayerful woman. 16. Straw man fallacy. Misrepresenting an opponent s position (intentionally or unintentionally) in order to defeat weak version of the argument. Evolution?! How can you possibly believe that all this came about by chance?! 6-day creation?! Don t you think that science can tell us anything about the world? Doctrinal preaching is a bad idea. We need expository preaching we must let the Bible speak on its own terms. 17. Fallacy of alleged irrelevance. Claiming that an argument is irrelevant on the grounds that you cannot see its significance. Disagreements about infralapsarianism and supralapsarianism can t be that important! What s the point of discussing how many angels can dance on the head of a pin? I don t know why food is such a big deal in Daniel 1, but it s probably not important. Why are we reading Turretin s Institutes of Elenctic Theology? I ve got to prepare my Bible study! 18. Unrepresentative sample. A conclusion is drawn about a large set of data on the basis of an unrepresentative subset of that data. Everyone I ve spoken to loves my preaching. Everyone I ve spoken to wants the prayer meeting to be on Monday. All the charismatic churches I ve experienced have appalling preaching. 4

5 19. False Analogy. Arguing for one proposition on the basis of an analogy that is dissimilar in a relevant respect. Preaching a sermon is like baking a cake: just chuck it all in and it ll come out fine. You don t need to go to church in order to be a Christian any more than you need to go to Old Trafford in order to support Manchester United. Question: what are the relevant differences here? 20. Fallacy of Exclusion. Ignoring or excluding evidence that would alter the conclusion of an argument. Lying is always wrong because that s what the 9 th commandment says. Women should never teach adult men because that s what 1 Timothy 2 says. Every Christian has the Spirit, therefore no Christian can receive more of the Spirit or be filled with the Spirit in a new way. Christians shouldn t go to court, because that s what 1 Corinthians 6 says. Question: what relevant data have been excluded in these examples? 21. Fallacy of complex cause. One part of a cause is treated as if it were the sufficient cause. What you need to sail around the world is determination. What a healthy church needs is a focus on evangelism. 22. Fallacy of insignificant cause. An insignificant part of a cause is treated as if it were the sufficient cause. What you need to sail around the world is a hat. What a healthy church needs is smart notice-sheets. 23. Fallacy of reversed causality. The relationship between cause and effect is reversed. An early symptom of scurvy is the inability to digest citrus fruit. We ll start providing youth work when a few more young people start coming to church. 24. Fallacy of unrelated cause. Locating the cause of a phenomenon in an entirely unrelated factor. As soon as we started providing decaffeinated tea and coffee after church, the stock market collapsed, therefore Fallacy of weak correlation. Locating the cause of a phenomenon in an effect which is related, but not strongly. As soon as we started providing proper filter coffee after our services, the congregation began to grow rapidly in maturity. 5

6 Question: How do you determine (a) which other causes may be involved, and (b) the importance of their respective contributions? 26. Fallacy of equivocation. Ignoring the fact that a word or phrase is being used in two different senses. Modern theologians deny the authority of Scripture, theologian X is a modern theologian, therefore... Johnny believes on the basis of 2 Peter 2:1 that the elect spoken of in 1 Peter 1:1 can fall away, therefore he denies that the elect predestined by God from eternity are all finally saved. 27. Affirming the consequent. Affirming a proposition on the basis that a consequence of that proposition is true. Formally: (1) if p then q; (2) q; (3) therefore p. Like this: (1) If it rains (p) the picnic will be cancelled (q); (2) the picnic is cancelled (q); (3) therefore it s raining (p). The reason this fails is that the consequence q may have other sufficient causes. If Jesus could return at any moment (p), then we d need to be really serious about evangelism (q). Since we know that we should be really serious about evangelism (q), it must therefore be true that Jesus could return at any moment (p). 28. Denying the antecedent. Denying a proposition on the basis that a cause (antecedent) of that proposition is false. Formally: (1) if p then q; (2) not-p; (3) therefore not-q. Like this: (1) If it rains (p) the picnic will be cancelled (q); (2) it s not raining (not-p); (3) therefore the picnic will not be cancelled (not-q). Again, this reason fails because the consequence q may have other sufficient causes. If Jesus could return at any moment (p), then we d need to be really serious about evangelism (q). So if you didn t believe that Jesus could return at any moment (not-p), then you d just give up on evangelism (not-q). You d be more likely to hear this fallacy in a form like this: People who don t think that Jesus is coming back soon will tend to give up on evangelism. Question: what other reasons might be given for taking evangelism seriously? 29. Humour and ridicule. Deploying humour or ridicule inappropriately, or to avoid the issue, or to cast unwarranted aspersions, or in the absence of a reasoned argument. You can never take Liberals seriously they never know what to say if someone asks, What must I do to be saved? Question: is humour or ridicule ever appropriate in theological argument? Biblical examples? 30. The fallacy fallacy. Maintaining a position on the grounds that you have heard the opposite position maintained on the basis of flawed logic. 31. Oversimplification. Simplifying a situation or argument to an inaccurate or absurd degree. Catholics believe in the sacraments, whereas Protestants believe in the word. 6

7 Keeping the Sabbath is legalism. The New Perspective denies the doctrine of justification by faith. To claim that extra-biblical information can help us to interpret the Bible undermines the perspicuity (clarity) of Scripture. 32. Genetic fallacy. Attacking an idea on the grounds that its source or supposed motivation is unworthy in some way. He would believe that he s a liberal. Of course she believes in remarriage after divorce she s a divorcee. Tom Weinandy? But he s a Roman Catholic! 33. Guilt by association. Attempting to discredit a conclusion by suggesting (not proving) a connection with other people, theological positions etc. that all parties agree (or, according to the speaker, ought to agree) are bad in some way. I don t like the idea that the Gospels were composed from pre-existing fragments of oral and written tradition that s the sort of thing Liberals believe. Belief in predestination leads to hyper-calvinism, and undermines enthusiasm for evangelism. 34. Inconsistency. Arguing for a conclusion whilst simultaneously maintaining another position that is logically incompatible with it. God is sovereign, but he doesn t constrain our choices. I do believe in penal substitutionary atonement; I just don t believe that God is personally angry at sin. 35. Stolen concept fallacy. Arguing for a conclusion whilst simultaneously attacking another position on which it logically depends. Unbelievers do this all the time! I don t believe in God; we should all just respect each other. 36. Nothing but objections. Continually raising objections, or merely hinting at their existence, as a means of avoiding the issue. Penal substitutionary atonement raises all kinds of problematic implications for the doctrine of the Trinity. 37. Red herring. Attempting to avoid engaging with an argument by raising an unrelated subject. [Example overheard during a conversation about why one should not attend a Roman Catholic Mass:] Well, plenty of stuff that goes on in some evangelical churches is pretty unhelpful too! 38. Tu quoque (lit. you too ). Arguing against someone on the grounds that their position, like yours, is also problematic. 7

8 I know my reading of v. 1 doesn t square with v. 2, but your reading doesn t square with v Occam s razor fallacy. Arguing in favour of a conclusion on the grounds of its (alleged) simplicity. The interpretation of Revelation 13 / Revelation 17 / Daniel 7 12 has been clouded by endless discussions of the identity of the kingdoms or individuals to whom the different beasts correspond. It becomes much simpler, however, once we realise that they all refer in a general sense to ungodly human political power. 40. Fallacy of the beard. Rejecting a concept or argument because of borderline cases that are difficult to adjudicate. How many hairs do you need before you ve got a beard? One? Two? Ten? Seventy-three? Well, if you can t tell me, then I m afraid the notion of a beard ceases to have much relevance. How many packets of crisps per day counts as greedy? One? Two? Ten? Seventy-three? Well, if you can t tell me, then I m afraid the notion of greed ceases to have much relevance. You run into all sorts of problems if you think the OT law teaches us about the Christian life remember all that stuff about boiling goats in their mother s milk? 41. Paradigm or cultural fallacy. Taking one s own system of thought or culture as the standard by which all others must be judged. One ought to wear a tie to church; anything less is a gesture of disrespect to the Almighty. But that contravenes the Westminster Standards! But that s not what Pastor Jim always told me! 42. Fallacy of the undistributed middle ( All that glitters is not gold ). Gold glitters, John s eyes glitter, therefore John s eyes are gold. Evangelicals really believe in preaching, and John believes in preaching, so John s an evangelical. 43. Ad antiquitatem (lit. from oldness?). Assuming that something must be right because it has been believed for a long time, or because it was believed a long time ago. None of the Church Fathers denied a literal 6-day creation. Question: does the fact that an idea has a good historical pedigree have any relevance? Why / why not? 44. Ad Novitatem (lit. from newness?). Opposite of 43: Assuming that something must be right because it is a recent idea. No serious modern scientists believe in a literal 6-day creation. 8

9 Further resources There are many textbooks on logic, some of which are quite useful (though usually very dull). Also well worth consulting (and much more exciting) are: David Field, Thinking about Ethics, in Introduction to Christian Ethics (Lecture course, Oak Hill Theological College; online An outstanding resource, from which much of the above is taken. John M. Frame, Doctrine of the Knowledge of God (Phillipsburg: Presbyterian and Reformed, 1987), pp